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Are you experiencing problems with your exterior walls, such as damp or stained interior finishes or mold? Are the occupants of your building reporting thermal discomfort in occupied spaces adjacent to exterior walls? Are your building’s energy costs unusually high? Any of these issues may be caused in whole or in part by thermal bridging within your exterior walls.
Heat flows through thermally conductive materials such as steel, metals, concrete and, to a lesser extent, wood. The heat flow through conductive materials is known as “thermal bridging.” Under circumstances where significant temperature differences (from exterior face to interior face) develop within exterior walls, a building’s energy efficiency can be notably impacted by thermal bridging, resulting in increased energy costs. Significant “thermal gradients” associated with thermal bridging can also result in water vapor (humidity) condensation on cold surfaces. The effects of condensation within the wall assembly, particularly if the rate of wetting is greater than the rate of drying, can result in the further reduction of the walls’ thermal effectiveness, microbial growth, and the premature deterioration of wall components.
Since all building enclosures experience thermal bridging to some degree, managing or reducing the impacts of thermal bridging in exterior wall assemblies should be considered during retrofit applications. Remedial measures to reduce the effects caused by thermal bridging may include the installation of continuous exterior insulation, providing thermal breaks in metal components within the wall, maintaining or improving the rate-of-drying of the wall, and maintaining/improving the wall thermal efficiency.
The installation of exterior continuous insulation with thermally broken girts is an effective method to reduce the impacts of thermal bridging. The addition of thermal breaks incorporated into wall designs, constructed from low thermally-conductive materials such as fiberglass and plastics will reduce the transfer of heat flow, and as such, reduce the risk of condensation and mold growth. Evaluation of the causes, effects and appropriate remedial solutions require careful consideration of the existing and proposed wall assembly components by a building enclosure specialist.
To assist in determining the most appropriate methods to improve thermal performance in wall systems, various software programs are available to analyze the effects of adding insulation and/or new cladding systems. WUFI uses a hygrothermal modeling that calculates heat and moisture transfer in multilayered building enclosures. THERM is a program that models two-dimensional heat transfer effects in building components where thermal bridging is a concern.
Thermal bridging should be a constant concern in the design and construction of building retrofits. The effective management of heat flow and drying of wall assemblies will help to mitigate the potential for condensation, deterioration of wall components, mold growth, and improve a building’s overall energy efficiency and thermal comfort of the occupants.
To mitigate runway/taxiway and apron wear caused by heavy use and climate conditions on these long stretches of asphalt, effective regular maintenance is the key to keeping runways safe. Therefore, finding the right pavement treatment process is essential. Below are two (2) options:
P-626 Emulsified Asphalt Slurry Seal Surface Treatment
P-626 is the Federal Aviation Administration (FAA) specification for slurry seal surface treatments. A slurry seal is a homogenous mixture of emulsified asphalt, water, well-graded fine aggregate, and mineral filler that has a creamy, fluid-like appearance when applied. Slurry seals are used to fill existing pavement surface defects, as a preparatory treatment for other maintenance treatments such as bituminous paving overlays, or as a wearing course.
- Prior to applying the slurry seal; loose material, oil spots, vegetation, and other objectionable material shall be removed.
- Tack coat is usually required prior to applying the slurry seal If the surface to be covered is extremely dry and raveled or if it is concrete or brick
- It is recommended to treat cracks wider than 0.25” in the pavement surface with an approved crack sealer prior to application of the slurry seal.
How Slurry Coats are Applied
Slurry seals are applied using a special truck that contains various compartments holding the aggregate, water, polymer modified emulsion, and other additives, which are mixed in the on-board mixer. The slurry mixture then flows out of a dispensing system mounted on the rear of the truck and onto the pavement within the confines of a spreader box. The box serves to distribute the slurry mixture over the pavement. Workers with squeegees follow behind, assisting in spreading the mixture, correcting areas not properly covered, and keeping the mixture off areas where the slurry is not intended to be applied.
How Do Slurry Coats Work
The slurry substance provides a new surface course and replaces the fines in the existing surface that have deteriorated over time. It fills minor cracks and restores a skid resistant surface. When applied, slurry seal will have a brownish color due to its ingredients. The slurry behaves like a viscous liquid, which makes it easy to spread across the entire application area. After it is smoothed out, the area is left to cure for at least 24 hours before it is available for use.
- Can be a long-term solution (5-8 years life expectancy)
- Cost effective ($0.76 per square foot)
- Restores skid resistance
- Protects the underlying pavement from aging and the environment
- Can peel or delaminate if not properly applied
- Can cause issues with rapid tire wear
- Can only be applied during warm weather
- Severe Foreign Object Debris (FOD) can occur if underlying surface is not properly prepared to receive the treatment.
P-608 Emulsified Asphalt Seal Coat
P-608 is the Federal Aviation Administration (FAA) specification for a specialized type of Emulsified Asphalt Seal Coat. Sealcoating is the process of applying a protective coating to asphalt-based pavements to provide a layer of protection from the elements: (water, oils, and U.V. damage.) the most commonly used Emulsified Asphalt Seal Coating is GSB-88 (gilsonite sealer-binder emulsion). GSB-88 uses an emulsified asphalt that contains 20% Gilsonite and a medium to fine graded sand. The Gilsonite additive and the use of more finely graded aggregate differentiate it from more conventional Seal Coats.
- Repair any cracks, potholes and other damages prior to applying seal coat.
- Make sure to clean off any leaked automotive fluid from the pavement, power wash pavement or use an air broom or a wire brush to ensure that the pavement is thoroughly cleaned.
- The pavement should be completely dry before the sealant is applied.
How is it Seal Coating Applied?
Being of low viscosity, Seal Coating is typically sprayed using application equipment that can apply the required coverage rates evenly over the pavement surface. A truck equipped with spray units and a pumping/distribution system using positive displacement pumps is commonly used.
How Does Seal Coating Work?
Seal coating rejuvenates asphalt pavements by reintroducing oils and resins, that have been lost through oxidation and use, into the asphalt binder between aggregates. It is formulated to cure quickly and designed to penetrate the asphalt and rebind the aggregate, sealing out and protecting the pavement from the harmful effects of water and oxidation.
- Economical (0.25$ per square foot)
- Can be applied on grooved runways
- Fast cure
- Can be fuel resistant
- Protects from U.V. radiation and oxidation
- Provide aesthetic black surface
- Testing is minimally destructive compared to other treatments
- Can wear faster in high traffic areas
- Can only be applied during warm weather
- Life expectancy is 2-3 years
- Once it wears off, the pavement will begin to deteriorate at the same rate as prior to application
- Frequent reapplication can be detrimental to grooved pavement
Athletic lighting can increase a school or municipality’s ability to use and play on their fields at night, which is a benefit to athletes and communities. It can double or perhaps even triple a field’s scheduled uses, provided that the turf system can sustain the increased use. These systems often require approvals in most municipalities. This will vary depending on bylaws, regulations, and community feedback.
Athletic field lighting can sometimes create issues with abutters due to glare and light spillage. Lighting companies have developed ways to address these concerns. One effective method is using advanced light shields, which can control the direction of the light and reduce glare. Another common practice is to increase the mounting height of the lighting fixtures, which promotes a more vertical lighting direction. At lower mounting heights, light is cast horizontally creating more glare and light spillage onto adjacent properties. Increasing the mounting height may also reduce the number of light fixtures needed to maintain safe light levels across the field, which can effectively be more cost efficient. However, many cities and towns have buildable height restrictions, in which case a variance is required prior to construction.
Many cities and towns have local bylaws pertaining to the color temperature of the lights. Typically, if the city/town has a color temperature bylaw, it’s associated with indoor lighting and not the most efficient to produce the required illumination for safe outdoor athletic fields. The industry standard for outdoor sports lighting is to have a higher temperature, producing a crisper white with a slight blue tint, which provides optimum color for clarity, contrast, and efficiency. The higher color temperature can reduce the number of light fixtures needed to provide safer playing conditions.
Artificial turf is appearing on more and more airfields across the globe. Reasons for its use are varied and sometimes unexpected:
- Eliminates mowing in certain areas
- Makes areas of an airfield more visible
- Neutralizes Foreign Object and Debris (FOD) on pavement
- Protects aircraft and passengers from wildlife hazard
- Stabilizes runway/taxiway shoulders and safety area
- Combats the ill effects of erosion and jet blast
- Marketing and advertising
- Reduces wear and tear on aircraft
What Does It Cost?
Installed costs of artificial turf can range from $6 to $14 per square foot, depending on the location and size of the installation. Some of the industry-leading products are “AvTurf,” developed by ACT Global and “Air FieldTurf,” marketed by FieldTurf. Both companies are large artificial turf producers known for their sports field surfaces.
What Are the Standards?
Advisory Circular (AC) 150/5370-15B provides guidance for the planning, design, installation, and maintenance of artificial turf. The turf must comply with a myriad of strict FAA standards, including drainage characteristics, skid resistance, durability, and the ability to withstand jet blast. Infill and glue down requirements are also presented. Additionally, the artificial turf must meet standards for flammability, chemical resistance, resistance to ultraviolet rays, wildlife deterrence, and plant growth. Use of the AC is mandatory for all AIP funded projects, including turf.
Where Can It Be Used?
Currently, on AIP funded projects, artificial turf may only be used in traditionally grassed areas – adjacent to pavements or on “paved” areas not intended for aircraft movement. Projects funded at the state level or by the airport may provide an opportunity to use turf as the surface on low-traffic taxiways, aprons, or even runways.
How Does It Perform?
While artificial turf has emerged as an innovative alternative to traditional turf, many installations remain relatively young. Its long-term performance and viability are still to be determined. Testing is ongoing. As an engineering firm with specialists in both artificial turf athletic facilities and airfield design, Gale is watching the growth of artificial turf on airfields with interest, and considering it where applicable to produce the best projects for our airport clients.
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Gilding is a decorative technique that adds beauty and protection to any building element by applying fine gold or powder to solid surfaces such as wood, stone, glass or metal, to create a lustrous and grand look. Gilding has been widely used as early as 2300 BC. The term gilding covers several techniques for applying fine gold or powder to solid surfaces to create a finished product that appears to be solid gold, at a fraction of the cost and weight. Gold is resistant to corrosion, which makes it an excellent metal for outdoor and indoor use, adding a protective layer to an otherwise exposed architectural detail. If applied properly and left undisturbed, exterior gilding can last more than 30 years, and interior gilding can last for centuries. The two primary methods of gilding are oil and water gilding, but the latter is not suitable for outdoor details.
The earliest recorded use of gilding is currently estimated to be in Egypt, where it was used in tombs, coffins, sarcophagi and other artifacts. In Rome, gilding was used on ceilings of palaces and temples, which later extended into churches and government buildings in Europe. The gold leaves made today are about 100 times thinner than the ones made in ancient Egypt, but other than that, the technique has remained unchanged for thousands of years. Today, gilding is used in many ways, including domes, ceilings, walls and architectural details. Gold provides a reflective surface that can help lower cooling costs when applied to outdoor roofs (or even windows), and it offers a warm glow when applied to indoor elements.
The gold leaf used in gilding is gold that is hammered or cut into very thin sheets, thinner than standard paper and semi-transparent when held to the light. Two commonly used styles of gold are loose leaf gold and patent gold leaf. The term “loose” refers to the method of packaging, in which the loose gold leaf is packaged between thin papers that have been lightly dusted with rouge powder. Patent gold leaf comes adhered to a backing sheet, or wax paper, and can be applied by holding the protruding edges of the paper.
Gold leaf is manufactured in a wide range of karats (kt) and can be modified with silver and copper for different colors and architectural themes. Gold is highly resistant to corrosion, which makes it an excellent metal for outdoor use. It provides a protective barrier that extends the service life of the product it is applied to, and it does not tarnish. An outdoor detail will require a 23kt to 23.75kt leaf that ranges from 96% to 98.5% in purity. Karats less than 23 are recommended for indoor use.
The results of this technique create a coating with unmatched perfection and brilliance worth the investment. The reflected light in gold enlivens flat surfaces and creates joy and fascination that will last for decades.
Vegetation management is required at virtually all airports. Overgrown vegetation can cause a variety of problems including:
- Provides habitats for wildlife, which in turn creates hazards to aircraft operations
- Tall grass can obstruct airport lighting and signage
- Shrubbery and small trees can obstruct airfield visibility and create potential obstacles in the event of a runway excursion
- Larger trees, particularly off-airport, cause hazards to aircraft approaches and takeoffs.
The amount and variety of vegetation at each airport, along with varying terrain will dictate what is required for management. Gale has recently assisted several airports with the acquisition of compact track loaders (commonly referred to as skid-steers) used for vegetation management, as well as other applications. These machines often come with multiple attachments, which increase the equipment’s versatility. Attachments can include:
- Forestry Disc Mulcher
- Brush Mower
- Hydraulic Pallet Forks
- Pick-up broom
- Box Plow Snow Pusher
- High Flow Snowblower
Using a track loader, with any of these attachments, allows an airport’s maintenance crew to accomplish many tasks from routine mowing and plowing of aprons and building areas, to removal of trees up to 10 inches in diameter. The versatility of a track loader provides a cost-effective solution to site maintenance and vegetation management issues that would otherwise require multiple pieces of equipment to tackle the tasks.
More From Our Blog:
- LED or Incandescent Airfield Lighting?
- FAA DBE Program Resources
What is LEED Neighborhood Development?
LEED Neighborhood Development (LEED ND) is the US Green Building Council’s (USGBC) newest sector of project certification. LEED ND was created to motivate architects, engineers and planners to help create more sustainable and connected neighborhoods, and combat urban sprawl.
Does Your Project Qualify?
The LEED ND rating system consists of two categories: LEED ND Plan and LEED ND Built Project:
- Plan certification applies to neighborhood-scale projects currently in any phase of planning and design, and up to 75% constructed.
- Built Project certification applies to neighborhood scale projects near completion or completed within the past three years (substantially built).
The LEED ND Rating system has five categories, each with prerequisites and category-specific credits that earn points. These categories, and the number of points earned, determine if the project will be designated LEED Certified, Silver, Gold or Platinum.
Why Get Your Project Certified?
- Plan certification can help developers in fundraising by promoting the project’s sustainable intentions.
- Built Project certification helps substantially built projects earn recognition for their sustainability.
- LEED certified developments generally have lower operation costs, reduced waste sent to landfills, benefit from energy and water conservation, provide more healthful and productive environments for occupants, and reduce greenhouse emissions.
- In many cities these projects qualify for tax rebates, zoning allowances and other incentives.
Who Can Help Get Your Project Certified?
Every project aiming to achieve LEED certification earns one point towards certification with a registered LEED professional on the project team. A LEED AP ND registered professional can guide the developer towards their certification goal.
Want More Information?
- Visit the US Green Building Council’s website to view their in-depth guide to LEED ND.
- Contact Gale Associates to speak with a LEED AP ND registered member of our Civil Engineering Department.
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Considerations for the Installation of Single-ply Roofing Membranes in the South During Cold Weather
While southern states do not typically experience the same harsh winters as their northern counterparts, temperatures can often fall below 40°F in the South during the winter months (though cold does not typically last, and snow is rare). Southern winters create a unique challenge for local construction professionals who may not be prepared or are unaware of the considerations required to perform roofing operations when temperatures dip low during colder months.
Most roofing materials are not designed for cold weather installation. Many manufacturers specify that their products (particularly adhesives and sealants) should not be installed when temperatures fall below 40°F. Additionally, products are typically specified to be stored within a specific “warm” range prior to use. If products are not used in accordance to their specifications, they could potentially not perform as designed and even void the manufacturer’s warranty.
Single-ply membrane considerations during cold weather applications:
- Rolls of membrane become less elastic, and therefore require extra time to visually “relax” prior to installation.
- Condensation and frost formation can occur on the back side of the membrane.
- Blistering and rigid wrinkles could more readily form.
- Poor or false welds could occur during installation. Welding seams and laps should be performed slower and with extra care. Also, more weld tests should be performed, especially in the mornings and after long breaks, to gage the mating surface integrity.
- Many manufacturers recommend membranes be stored in heated areas and brought to the roof just prior to installation.
Precautions to consider when installing single-ply membranes in cold weather include the attachment method of the roof membrane to the underlaying roof system substrate (i.e. rigid insulation, gypsum coverboard, bare concrete, etc.). For lightweight insulating concrete (LWIC) decks, fully-adhering the roof membrane with a water-based adhesive is frequently the most used attachment method. Water-based adhesives are favored over other types because of their low VOC, ease of clean up, ability to spread, and versatility. However, because they are water-based, temperature considerations are important for the roof system’s long-term performance.
Water-based adhesive considerations for colder weather applications include the following:
- Longer cure time required for temperatures less than 40°F (as well as highly humid conditions). Most manufacturers specify for their adhesives to be applied only when temperatures are 40°F and rising, and the humidity is less than 90%. Cures can have a potential duration of two-to three days, which can be affected by freezing temperatures.
- Manufacturers typically specify that their products be stored at temperatures from 60-80°F, necessitating the need for a “hot box” on the roof or staging area.
- If adhesives and sealants do freeze, they will remain in the solid state even when warmed. The materials should be discarded and not attempted to be salvaged by mixing or reconstituting.
- Adhesives and sealants typically should not be used when the ambient temperature is expected to fall below the dew point during application, and up to six hours after, and if the forecast includes freezing temperatures within 48 hours of application.
- Shipments of water-based adhesives may be limited to certain geographic locations in colder weather months.
- Condensation on the surface of the adhesive will impact adhesion to the substrate.
- Application of adhesives should be scheduled near midday, when temperatures are their highest.
- The substrate being adhered should also be at 40 degrees Fahrenheit and rising.
- As construction may have stockpiles of water-based adhesive in their shops, confirmation from the manufacturer’s local representative should be provided for the acceptance of their product’s application on a project during forecasted cold spells.
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Undertaking an athletic field construction project requires thorough research to choose the playing surface for the field that best aligns with the athletic program’s goals and budgets. When considering the construction of a competition level athletic field, it is important to understand the basic differences, and advantages/disadvantages, between natural turf and synthetic turf fields.
Natural Turf Fields:
Environmental Benefits: A natural turf field reduces excess stormwater surface runoff by allowing water to infiltrate into the soil, additionally, the surface temperatures of natural grass are markedly cooler than synthetic turf.
Limitations: Overuse and excessive traffic on natural turf can lead to compaction and bare spots. Inclement weather can lead to overly saturated soils or standing water which limits playability, or the fields may experience irreparable damages if played on when saturated.
Turfgrass Types: Cool Season and Warm Season: Cool Season grasses are prevalent in the northern regions of the U.S. and typically consist of Kentucky Bluegrasses, Perennial Ryegrasses, and Tall Fescues. The Warm Season grasses, which are prevalent in the southern regions of the U.S., are the Bermudagrasses.
Natural Turf Field Construction: Natural turf athletic fields can generally be classified into three types of construction:
- Natural with Native or Amended Soils
- Sand Cap Over Native Soils
- Sand-Based Rootzone
Irrigation: To keep the field in optimal playing condition, irrigation is essential.
Maintenance: A rigorous maintenance program is important to maintain a consistent and attractive playing surface, promote player safety and to protect the turf & root systems.
Synthetic Turf Fields:
Benefits: A synthetic turf field provides a durable playing surface with a grass-like look and requires lower maintenance than natural turf. Synthetic turf fields are well drained, can be plowed in snowy conditions, have near all-weather availability for play, and the field lines and markings can be permanently inlaid, which eliminates the need for continual re-striping with paint.
Limitations: Synthetic turf fields are more expensive to install than natural turf fields. They have a higher surface temperature and do not filter air or water pollutants as natural turf does.
Elements of Synthetic Turf Fields:
Turf Carpet: The carpet fiber materials are manufactured from either polyethylene, polypropylene or nylon materials and are produced into fiber strands known as “slit film” or “monofilament”. The blending of slit film and monofilament together, known as a “dual fiber” system has become popular for multi-sport fields and provides a versatile, durable playing surface.
- Turf Infill: The most common infill material has typically consisted of a blend of a blend of silica sand and recycled crumb rubber (SBR). As the synthetic turf industry has progressed with thorough research, a number of “alternate” infills have been developed and introduced to the market, and appear to offer viable options for consideration.
- Impact Attenuation Pad: The attenuation pad is a resilient layer that is incorporated between the base stone and the turf carpet. This layer helps to support performance characteristics, control ball bounce, and is designed to reduce player impact and injuries.
For a more in-depth discussion regarding natural v. synthetic turf athletic fields, click here.
You may also be interested in this additional information:
- Athletic Facilities Planning and Design
- Synthetic Turf Warranties and Replacements
- HIC and GMAX Testing
Woodpeckers can wreak havoc on building enclosures. Found across the globe, woodpeckers traditionally peck holes into trees to find food, make nests, and communicate. However, woodpeckers and other pecking birds, such as flickers, can mistake Exterior Insulation Finish Systems (EIFS) for wood and cause building damage. Woodpeckers are very territorial and defend their domain by tapping on materials that produce the “right sound.” EIFS is one of those materials. Not only is damaged EIFS an eyesore, it can also make a building vulnerable to water intrusion, mold, and/or pest infestation. Most damage occurs during the breeding season, March through May, when the birds are at their most territorial.
EIFS is comprised of a water-resistive barrier that covers the exterior substrate (often plywood or oriented strand board [OSB]), a drainage plane, a rigid insulation board, a base coat, a mesh of glass-fiber embedded in the base coat, and a finish coat. Woodpecker damage is consistent with circular holes of various sizes through all or most of the layers, down to the substrate. Woodpeckers tend to peck at secluded and shaded areas such as eaves, decorative trims, and ledges. When EIFS is substantially damaged, often the only remedy is to replace the entire affected panel. Woodpeckers will return annually, causing damage year after year. Even if they don’t return, other small birds will often make a nesting site in any large enough hole that is not repaired.
Common solutions include using plastic hawks or owls, rubber snakes, metal screens, mylar tape, as well as “trap and release” programs. All of these have proven less than effective. Woodpeckers are also classified as migratory, non-game birds and therefore, are protected from lethal means or nest destruction.
Newer solutions to reduce bird damage include strengthening the mesh matrix, hardening the finish and base coats, or both. One such product, EIFS “Armor,” addresses the problem from both fronts by using a diamond mesh system with an acrylic hardener additive. Some EIFS manufacturers have added a repellant into their products to make them less attractive to woodpeckers. BeakGuard by Stuc-O-Flex tries to solve the issue by adding a blend of ingredients into their finish coat that creates an unattractive taste to the birds, and acts as a deterrent. Also, they report that their blend is stronger and more durable than other non-treated EIFS finish coats.
None of these methods are fool-proof, but they may lower the lifetime maintenance costs and keep buildings looking better for a longer time.
Restoration and repair of multi-wythe masonry structures may require in-place strengthening. When rebuilding cracked, deteriorated, or displaced masonry assemblies is not practical, economical, feasible, or safe; in-place strengthening may be the appropriate solution. In-place strengthening is particularly appropriate for masonry walls supporting significant loads: wall corners and walls with large openings. When masonry walls have experienced internal movement, the result may be separation between wythes or the face cladding (stone) from a brick back up wall. Such separation results in reduced load bearing capacity. Methods available for in-place strengthening include installation of, stainless steel wall ties, grouted reinforcing steel, and stainless-steel masonry anchors with ports for injecting structural grout.
For historic structures constructed with hydraulic lime mortars, it’s important that structural grouts are compatible with the functioning of the existing assembly. ASTM 1707 provides current standards for pozzolanic hydraulic lime (PHL) for structural applications. PHL structural grouts are breathable, cure within a wall cavity, provide moderate compressive strength, and accommodate movement within masonry assemblies. Such movements include those commonly caused by settlement and freeze thaw-cycles.
Wire glass was widely utilized in buildings constructed in the late 1800s and early 1900s. At the time, it was considered to be the most innovative glazing product in terms of safety and aesthetics. Today, wire glass is often viewed as a historic feature to be conserved; however, there are several things to consider in regard to wire glass applications.
During the Industrial Revolution, the shift from skilled labor to large-scale manufacturing made the use of glass in building construction much more feasible. Plate glass was used in buildings where abundant light was needed, such as in factories, train stations, and greenhouses.
Issues arose with these glazing applications. The glass lites, which were installed in steel frames, shattered as a result of differential expansion and contraction between the respective materials. Additionally, many buildings were subject to intense vibrations, smoke, and heat from locomotives and machinery, which would result in broken glass. To address these safety hazards and maintenance issues, several options were explored, including using wire netting on the interior of the glass, wood framing instead of iron, and iron shutters. Each of these options presented advantages and disadvantages. The wire netting on the interior of the glass often corroded quickly from steam and also prevented workers from cleaning the glass. Furthermore, the openings in the netting were typically not small enough to capture all shards of glass when broken. The use of wood framing addressed the issues associated with expansion and contraction; however, the flammable nature of wood presented concern for industrial buildings such as factories and train stations. Lastly, the use of iron shutters protected worker from breaking glass, but they constantly required maintenance due to corrosion and ultimately blocked the much-needed light.
Following these failed solutions, a new product was born: wire glass. By embedding the metal wire netting within the glass, the issues regarding corrosion and maintenance were addressed. The wire glass also solved the issues related to expansion and contraction of its plate glass predecessor. At the turn of the 20th century, wire glass was advertised as shatterproof and fire retardant and quickly became widely utilized.
The decline of wire glass can be traced to the period of the World Wars. Due to wartime production needs, the availability of metal for wire glass diminished. Additionally, more economical and less complex types of glass, such as laminated, tempered, and float glass were developed.
RESTORING OR REPLACING HISTORIC WIRE GLASS: THINGS TO CONSIDER
Is your building historically significant?
If your building is listed on the National Register of Historic Places, it is important to maintain your existing wire glass features. Unfortunately, the types of wire glass that were utilized in the early 20th century are no longer produced today, There are salvage companies throughout the United States that can provide historic wire glass, although finding an exact match may prove to be difficult and large pieces are typically unavailable. While historic wire netting is not manufactured in the US, it may be obtained abroad, but lead times and cost may be prohibitive. It should be noted that there are currently no methods for repairing damaged historic wire glass. Once the glass has broken, the wire netting is exposed and is subject to corrosion. Epoxies or resins that could be used to fill cracks often discolor and are noticeable; therefore, replacement is the primary option for damaged wire glass.
Is maintaining the existing aesthetics important to you?
If maintaining the existing aesthetics is important, but perfect accuracy is not a concern, there are replacement wire glass products available in the United States. These products are typically thicker than historic wire glass and the wire netting often has a different patina. Additionally, the wire netting within this glass usually has a diamond pattern, whereas historic wire netting typically had a hexagonal or sinusoidal (“wavy”) pattern. As a result, the differences in thickness and aesthetics may require the replacement of more lites than anticipated.
If maintaining the existing aesthetics is not important and the project focus is to upgrade the glazing, glazing options are available to fit your current needs. There are numerous exterior glazing options beyond wire glass that can provide increased R-value, different levels of light emittance, patterns for privacy and light diffusion, etc.
Does your wire glass application meet building codes?
There are several applications where traditional wire glass is no longer acceptable. These include vision panels and sidelites. Safety wire glass, which incorporates a safety film for additional impact resistance, would be required to comply with building codes when installed at these locations. Building code research is recommended in advance of design and application to verify compliance.
Many airports are considering the differences between incandescent and Light Emitting Diode (LED) fixtures for runway and taxiway lighting. Each has its advantages and disadvantages:
Incandescent: Incandescent lights have a lower initial cost but higher operational costs than LED. Further, incandescent bulbs have a substantially shorter bulb life. In the Northeast and other snowy areas, airports may prefer incandescent fixtures because the bulbs emit heat and help to melt snow around the fixture’s lens – making them more visible than LED during and after snow events.
LEDs: In contrast, some users favor the longer lasting and lower operational costs of LED light fixtures, although initial costs are higher than incandescent fixtures. The longer life span of the LED light bulb will reduce the frequency of maintenance. In colder climates, LED lights can be fitted with an “arctic kit” that adds a heating element to help melt snow around the fixture’s lens, but these kits contribute to an increase in power consumption and initial costs, reducing their overall cost advantages over incandescent lighting. Furthermore, there are questions regarding the effectiveness of the heating elements.
The choice between these two systems should be tailored to the airport’s specific conditions; however, regardless of the lighting chosen, these maintenance tips can help:
- Do not mix incandescent and LED fixtures on a runway or taxiway. The difference in perceived color or brightness may distort the presentation of the lights to the pilot’s eye.
- Replacement bulbs should match the manufacturer’s specification. Do not use an LED bulb on an incandescent fixture or vice versa.
When maintaining runway or taxiway lights, consult as-built and shop drawings of the installed lighting system. As-built drawings typically number each light fixture, making identification of the proper fixture easier for an electrician or other maintenance person. Also, shop drawings typically contain the manufacturers name and fixture specifications – useful when ordering replacement parts. For these reasons, it is helpful to ask for a copy of these documents after an installation project.
- Last, for AIP funded airfield lighting projects, airports should specify spare parts as part of their bid documents, as permitted by FAA Order 5100.38D. This can help to maximize the use of federal funds and reduce inventory shortages to avoid delaying maintenance.
The use of “zero” or “low”- Volatile Organic Compounds (VOCs) in construction materials is on the rise, and with it are industry misconceptions that low-VOC materials (such as adhesives, primers, coatings, or sealants) are odorless and tolerable to the indoor air environment. Facts prove it may be just the opposite.
Many construction materials and everyday household products have odors and VOCs that may impact those with sensitivities. For example, hospitals, particularly Operating Rooms (ORs), have the distinct aroma of clean medical equipment and hand sanitizer. Imagine a hospital forced to shut down their fully scheduled ORs due to the infiltration of an “odorless” low-VOC primer that bypassed the hospital’s preventative measures!
Since 2012, the roofing industry is required to follow federally mandated regulations to reduce VOC emissions to the outdoors. As a result, water-based adhesives, coatings, and primers have grown in popularity versus the much higher VOC concentrated solvents. Much of the popularity is the result of effective marketing strategies of manufacturers labeling their products as “zero” or “low”-VOC compliant materials.
Some certified labels are based on the VOC’s released from the product indoors and how the product may impact the health of the occupants. Other certification programs are based on the content of VOC’s that are regulated to control the outdoor air pollution, resulting in a lack of standardization and misconceptions regarding VOCs.
So, how can industry professionals, building owners and managers combat VOC odors and protect their occupants?
- Inform the Design Team if the building occupants are sensitive to construction odors.
- Request Safety Data Sheets (SDS) for each material from the contractor or manufacturer prior to the start of construction and consult an environmental health specialist. Require a full binder of SDS be left with the Owner’s Representative and for the contractor to keep a copy on the project site.
- Understand the operations of the building’s mechanical systems and air intake locations. Perhaps, it may be logistically feasible to systematically shut down any intakes while work is proceeding in the area.
- Implement preventative measures to reduce odors within the building’s mechanical systems by installing specialized filters at intakes, or scheduling temporary mechanical shut downs.
Small Unmanned Aerial System (sUAS) vehicles, known as drones, are gaining popularity in the Design and Construction Industry as an acceptable alternative to traditional aircraft or ground visual inspection data collection and recording methods. Drones utilized in commercial applications can only be operated by a FAA Licensed UAS Pilot. (FAA, 14 CFR part 107).
The industry is currently using drones to provide cost-effective and comprehensive analysis of various applications such as high definition building or site photography/video, photogrammetric survey of topography or facilities on project sites. Most drones are outfitted with on-board computers, allowing pilots to set up pre-programmed routes that can be duplicated on future visits, establishing consistency. Drones are also being used to improve building inspection safety by removing humans from potentially hazardous situations. This application is particularly useful on fire or storm damaged buildings, or in areas considered unsafe or difficult to access.
Typical drone use includes:
- High Definition roof, tower and facility inspections (versus crane, scaffolding, or other portable lift apparatus)
- Access and inspection of hard to reach building areas (historic slate roofs, towers, steeples, etc.)
- Access to impassable areas and structures due to natural disasters (hurricanes, flooding, mudslides, etc.)
- Terrain and facility feature photogrammetry
- Photographic documentation of existing conditions, areas that may require additional investigation, or repairs (high rise facade inspections)
Periodic construction process photography and time-lapse analysis
- Creation of 3D models of buildings and sites
- Development of orthomosaic images of sites/road/transportation systems to develop base drawings/site renderings
- Aviation facility obstruction measurement, tagging and analysis
Drone operations for commercial use require the Remote Pilot in Command to be assisted by another person while operating the sUAS on site to ensure continued flight safety and visual line of slight. As required by the FAA, operators must adhere to all operational requirements of part 107 for sUAS flights, including pre-flight checklists, airspace regulations, and flight log recommendations.
Click here for more information on our sUAS services and how Gale can help you.
The Field Tests Used to Determine Impact Resilience
Concussions are a hot topic in today’s sports world, and when it comes to synthetic turf fields, player safety is top priority. Synthetic turf playing surfaces may change as a result of turf fiber wear, infill displacement, and/or infill compaction. To monitor the playing surfaces and gauge performance requirements, fields can be periodically tested. The two field tests recognized in the athletic industry for determining impact resilience are GMAX, and Head Impact Criterion (HIC) testing.
Both the GMAX and HIC tests measure impact attenuation, or the amount of force a playing surface absorbs upon impact. Higher test values mean the playing surface is absorbing less impact and returning more force to the athlete, which can result in lower extremity injuries or concussions. The GMAX test, which uses a flat circular missile to measure body impact, has been used as the standard test for many years. However, the industry is looking to make HIC testing a standard in the near future. The HIC test uses a rounded spherical weight to represent the force of a human head impacting a playing surface. As such, the industry appears to be looking towards the HIC test as a standard to gauge the potential for concussions.
There are various ways to reduce impact and increase safety, including variations of the turf profile and infill system, as well as installing shock absorbing pads beneath the synthetic turf. Infill systems and shock pads can directly affect the GMAX and HIC test results because of their ability to absorb force upon impact. Whether you are considering replacing your turf carpet or infill system, installing a shock pad, or you simply have an aging field that needs testing, Gale now offers HIC and GMAX testing services.
Gale Associates, Inc. can provide additional information to support your decisions.
Contact John M. Perry, P.E. (New England) or Carolyn E. DuBois, ASLA (Mid-Atlantic / South East) to find out more regarding GMAX/HIC testing, or to schedule an appointment.
Severe flooding can endanger lives and cause billions of dollars in property damage. Even moderate levels of flooding can lead to destruction and disruption of building operations. Flood damage can occur from a variety of sources, including hydrodynamic/hydrostatic forces and debris impact, soaking, and sediment and contaminants. Flood water can destroy a building’s electrical infrastructure and mechanical systems, causing interruptions that can last from a few days to over a year.
Due to continued climate change and the 2016 revisions to the Federal Emergency Management Agency (FEMA) flood maps, many buildings not previously categorized as “at risk” are now subject to flooding. Because of this, if flood-proofing and mitigation steps are not taken, building owners face potential risks and associated increases in flood insurance coverage.
As defined by FEMA and the National Flood Insurance Program (NFIP), there are three types of flood-proofing measures to consider for non-residential buildings:
- Dry flood-proofing – A combination of measures that result in the building structure and its utilities being watertight and substantially impermeable to floodwater penetration. The building components should also have the capacity to resist flood loads.
- Wet flood-proofing – The use of flood-damage resistant materials and construction techniques to minimize flood damage to areas below the flood level of a structure. The area is intentionally allowed to flood.
- Floodwall / levee – Man-made barriers that are constructed to contain, control, or divert the flow of water so as to provide protection from temporary flooding.
Per NFIP regulations, non-residential buildings are only required to be protected to the base flood elevation (BFE), the elevation to which floodwater is anticipated to rise during the 1-percent-annual-chance (100-year) flood. However, extending the flood-proofing measures to the BFE +1 foot of freeboard can allow the non-residential building to achieve a favorable NFIP insurance rating. Flood-proofing to even higher elevations can result in savings in annual insurance premiums.
Design considerations when selecting flood-proofing measures may include performing a flood hazard evaluation of the site and a structural evaluation of the building. When considering flood-proofing measures that require human intervention, the implementation of a flood emergency operations plan is recommended to allow adequate flood warning time. A certified floodplain manager and registered professional engineer or architect can assist owners with regulatory requirements, building codes, guidance documents, and design standards.
Do you have a synthetic turf field that is approaching the end of its warranty period? If so, you may wish to consider having an expert perform an evaluation to determine if repairs are needed before warranty expiration. Typical warranty issues for a field of 7-8 years include: loose or torn seams, over compaction (resulting in harder playing surface) and excessive fiber loss or breakdown. Most synthetic turf manufacturer warranty periods last eight years and will cover remedying some of these issues at no cost to the owner.
If your field is past the warranty period, you may soon be considering replacing the turf carpet. Typical synthetic turf fields installed between 2000 and 2008 historically last approximately 10 years, depending on level of maintenance and usage. Newer fields with improved fiber and infill technology may last longer, up to 10-15 years. The benefit of a synthetic turf replacement is that most fields typically reuse the anchor curb, base stone, and sub-drainage, which affords a significant cost savings compared to original installations. In addition, if the field has experienced drainage issues, replacing the turf is a perfect time to improve it. In most cases, the original infill can be harvested for reuse while the turf carpet is disposed of or recycled.
Several new technologies in turf infills and shock pads are now available for consideration (shock pads reduce the “hardness” of fields to reduce the potential for concussions due to ground impact). Two field tests, HIC and Gmax, are used in the industry to gauge the potential for impact attenuation. While the Gmax test is still widely used, the industry standards are moving towards Head Impact Criterion (HIC) and Vertical Deformation testing. With new standards on the rise due to the awareness of potential concussions, many field installations are incorporating shock pads to improve player safety. Shock pads can easily be installed during a turf replacement.
With improvements in technology and the variety of federal and private programs providing options for installing photovoltaic (PV) arrays, or solar panels, building owners should be aware of the short- and long-term considerations, including cost implications for solar panel installations on roofs. From selecting photovoltaic system types and mounting options; to evaluating the existing roof system, building structure, monitoring construction, and considering future building maintenance and renovations; planning is paramount to avoiding unanticipated issues and unexpected expenses.
Improper planning can result in a multitude of complications, including roof leaks, structural damage, voiding roof system manufacturer warranties, and unforeseen costs. Consider reviewing the following items as you research the feasibility of installing photovoltaic arrays on your roof system:
- Evaluate the condition of the existing roof system prior to PV installation.
If a PV assembly is installed on a roof system that is nearing the end of its serviceable life or warranty period, costly removal, temporary storage/protection, and reinstallation, or modifications to the PV arrays may be required to replace the roof system. By performing an evaluation of the existing roof system in advance of PV installation, roof repairs or replacement can be sequenced to reduce the costs associated with PV removal and reinstallation.
- Perform an analysis of the existing structure.
Whether installing PV arrays in a ballasted assembly, or providing structural supports which penetrate the roof, additional dead, live, or wind loads may be imparted to the existing roof deck and structure. By performing a code review and structural analysis of the additional loads added to the structure by the PV system, the requirement for structural augmentation can be determined, and appropriately sequenced with roofing renovations and the PV installation, if appropriate.
Select the right PV mounting system for your roof and building.
Steel dunnage mounting assemblies connected to the roof structure allow solar panels to be installed at steeper angles which more efficiently collect solar energy than ballasted systems with low slopes. However, the steep panels can act as sails, increasing the lateral loads on the building and creating new locations for heavy drifting snow. Additionally, the support posts penetrate the roof and create potential paths for moisture intrusion. Ballasted tray support systems typically have a low slope and do not result in increased wind load reactions. However, they often employ concrete pavers as ballast, which adds additional gravity (dead) loads to the roof deck and structure, which could trigger the need for structural augmentation. Ballasted assemblies typically do not require many penetrations through the roof, and they may be less likely to result in leaks. Roof membrane protection pads are placed below the supports to reduce the potential for abrasion of the roof surface. Proprietary PV mounting or support systems are beginning to be supplied by roof manufacturers, although it is not recommended to install systems which do not have a proven track record.
Confirm with the roofing manufacturer their requirements for PV arrays being supported.
Different roofing manufacturers will have different requirements for the support of the solar panels and protection of the roof system. The roofing manufacturer’s guidelines will need to be followed in order to obtain, or maintain, the roofing manufacturer’s warranty. Some roofing manufacturers have developed proprietary systems in conjunction with solar panel providers so that multiple PV products can be covered under one warranty.
- Review the code for life safety and accessibility around roof mounted solar panels.
To increase the electrical production of solar systems, it is often advantageous to provide as many solar panels as possible. For low-sloped roof systems, this desire to install as many arrays as possible can lead to PV arrays being installed close to the roof edges. Fall protection or fall arrest systems are required to provide a safe working environment for subsequent maintenance to the roof or roof top equipment. Additionally, the roofing manufacturer’s walkway pads should be installed in the regular maintenance traffic locations to reduce the potential for slip hazards and provide redundant protection of the roof system. For steep-sloped roof systems, aerial lifts or scaffolding may be required to access the roof areas or solar arrays for maintenance, and these expenses should be considered during the initial planning process.
- Review the code for fire safety requirements.
Roof mounted solar arrays are subject to specific electrical and fire safety requirements which differ from PV systems installed on the ground. A professional knowledgeable with the electrical code and fire safety should be involved with the design and installation.
- Make a contractor part of the solar panel team.
Coordinate to have a licensed electrician and roofing contractor perform designated repairs or renovations before, during, and after the installation of the PV arrays.
- Install time-proven PV systems.
Over the years, various systems have been designed to integrate PV arrays into building components, and some have resulted in premature failures of the solar equipment or the roof systems. Thin PV films were once integrated into single ply roof membranes and were installed on numerous roof systems. However, after only a short time in service, the thin film PV arrays delaminated from the roof membrane because of different mechanical properties between the two materials, resulting in failed roof systems and a loss of PV function. Install PV and roof systems with a proven track record in the same part of the country as the current project to avoid becoming a case study.
Interior renovation/retrofit projects may require repairs to a building’s exterior masonry walls as a result of moisture intrusion and mold, or code-mandated improvements which may be triggered by a change in use. Walls and windows may also be retrofitted or repaired due to age-related deterioration, moisture intrusion damage, or to improve overall building aesthetics. The decision to retrofit is often implemented without properly evaluating the air, moisture and thermal behavior of the existing wall system; the conditions of the wall system; and without establishing reasonable performance expectations/criteria of the wall system. Proceeding with window replacement, prior to these considerations, may have detrimental effects.
When retrofits are required to correct damages related to waterproofing, window replacements are frequently included in the design because they are often associated with leaks, sometimes falsely. A closer look at the wall conditions may reveal that the wall itself is the source of leaks. Identifying and correcting these issues are paramount because moisture infiltration may lead to a damaged structure or health risks such as mold growth. Masonry cavity construction (wall systems with a one to two-inch air space or cavity between the interior and exterior walls) typically rely on through wall flashings and drainage weeps to direct moisture collected within the cavity out from the wall. Mass masonry walls and barrier walls do not include a cavity and rely on proper wall system and component performance to reduce the potential for moisture intrusion. If poorly constructed or in an aged and deteriorated condition, these wall systems can allow moisture directly through the wall. Therefore, understanding how the wall was intended to work is a key factor when considering a retrofit to correct issues related to leaks, as different wall systems warrant different retrofit options. If window replacement is necessary to correct leak issues, how the new window will work in conjunction with the in-place wall system behavior is critical to long-term performance.
Other retrofits triggered by changes in the building code or change in use; or a desire to improve thermal performance or aesthetics; often include the addition of new materials, such as air/vapor barriers and/or thermal insulation. It’s important to understand the interaction of the new and existing building materials and assemblies prior to constructing modifications, which can negatively affect the behavior of the in-place systems. Air/vapor barriers and thermal insulation are manufactured with varying degrees of vapor permeability. In general, water vapor (the gaseous form of water contained within the air) will travel from the warm side of a wall assembly to the cold side of the assembly. Determining which side is cold and which side is warm depends on the climate zone of the project location. For example, the warm side of a building wall in Texas will be on the outside, while the warm side of the wall on a building in Wisconsin will be on the inside. A building in a variable climate zone, will have both conditions, with the warm side of the wall alternating throughout the seasons. Therefore, different climates will require different strategies when retrofitting a masonry wall system in regards to thermal insulation and air/vapor permeability. Inappropriate or improperly placed air/vapor barriers and insulation can trap moisture against the wall itself or in an undesirable location within the wall. Vapor retarders could lead to slowed rates of drying and the development of mold. In general, air/vapor barriers must be placed so that moisture does not become trapped and cause water damage, or in colder climates, result in freeze/thaw damages.
Interior retrofit can have major ramifications on the performance of the wall, yet many retrofit projects are completed without considering the effects on the in-place wall behavior. Regardless of the reason of retrofitting, evaluations of the exterior wall, retrofit options, and their combined behavior are necessary to fulfill the goals of the project.
Asphalt tennis courts may be the most commonly constructed hard-surfaced courts in the industry today. However, due to inconsistencies with the quality of asphalt in recent years, there is an increased interest in post-tensioned concrete courts. When considering the construction of a tennis facility, it is important to understand the basic differences between asphalt and post-tensioned concrete courts.
Asphalt Tennis Courts:
- Installation typically includes two courses of asphalt (wearing and binder) over a crushed stone base. The depth of the pavement system is based on recommendations resulting from a geotechnical investigation/report.
- Bituminous (asphalt) pavement is flexible and tends to be more affected by freeze/thaw cycles. Over time and under exposure to the elements, this often leads to surface and/or structural cracks.
- The design mix has an impact on the pavement’s lifespan. It may be beneficial to avoid incorporating recycled asphalt shingles and recycled asphalt pavement into the asphalt mix. The performance grade of the asphalt binder used in the design mix should be specifically tailored to the climate / environmental conditions of the proposed project’s geographic location.
- Asphalt paving may be more economical to install; however, there are higher maintenance costs throughout the life of the court due to repairing cracks and related re-application of the tennis surfacing system.
Post-Tensioned Concrete Tennis Courts:
- Post-tensioned (PT) concrete construction involves installation of a structural concrete slab over a prepared base. The concrete is reinforced with cables tensioned after the concrete is installed. The design of the pavement system is based on recommendations from a geotechnical investigation/report, as well as design recommendations from a registered structural engineer.
- PT construction is a rigid pavement system, and when properly installed, has a greater resistance to cracking. Cracks that may occur are typically hairline rather than the more significant cracks commonly seen in asphalt courts.
- During design, it is important to take into consideration a clear space around the perimeter of the courts to allow for the tensioning of the cables.
- PT construct is more expensive to install than asphalt; however, lower maintenance costs over the life of the court are typically experienced. Post-tensioned courts do not require the extent of crack repairing (and related tennis system resurfacing) typically associated with asphalt courts.
- PT systems have longer service life than asphalt courts.
Budgetary constraints are often a primary factor in selecting either asphalt or post-tensioned concrete. While asphalt systems have a lower initial cost, higher maintenance costs and an overall shorter lifespan is expected. Post-tensioned courts are significantly more expensive to install; however, they require less maintenance over the life of the court, and have a longer overall life expectancy.
When evaluating existing structures, forensic test methods are often used to aid in the investigative process. Information regarding the material properties, conditions, and subsurface conditions is paramount in a forensic evaluation to have a clear understanding of the existing conditions. Destructive testing is typically the preferred method to determine existing conditions as it allows for “hands-on” access to the subsurface environment. Where possible, masonry and concrete samples are collected during destructive exploration for laboratory testing. The materials can be tested in a controlled environment to determine their performance characteristics. Often; for a variety of reasons, such as safety, cost, or access; forensic non-destructive test methods are used to evaluate existing structures. This is often the case in masonry and concrete evaluations where destructive methods may not be feasible due to their disruptive nature to the facade or building occupants.
The following are examples of non-destructive test methods that can be used to gather information on the in-situ properties of concrete and masonry structures during a forensic evaluation:
Sounding: used to determine surface delaminations in concrete and certain types of stone. The surface of the concrete or stone is struck lightly with a hammer and the resulting sound is interpreted by the engineer. High pitched sounds typically indicate sound/stable conditions, while lower pitched sounds can indicate delaminations.
- Impact Echo Testing: used to determine flaws in masonry and concrete using a spherical impactor and measuring the stress propagation through the speed of the sound wave. The test can also determine slab thickness accurately.
- Impulse Radar Testing: used to detect delaminations in masonry or concrete structures or debonding between masonry wythes in multi-wythe walls. As the wave travels through each wall material, the different components have different dielectric constant, including air. The energy reflected is measured and the depth to the defect can be determined. This is also used to determine steel reinforcing depth in concrete structures.
Rebound Hammer Testing: used to determine strength of concrete using surface hardness. The hammer is dropped on the surface on which the test is being performed and the rebound is measured; a correlation can be interpreted from rebound to the material’s compressive strength.
- Infrared Testing: used to determine areas of spalls and voids. A thermographic image is used to show areas with inconsistent materials that affect the thermal properties, resulting in a differing temperature from the surrounding area.
Each of the above tests is used in conjunction with visual observations, and performed and interpreted by a qualified professional. No one test can be considered the sole indicator of material condition. Multiple test methods in several locations are required to substantiate results. As with most exterior building enclosure evaluations, differing building constructions and conditions will necessitate the appropriate approaches and testing.
Re-Roofing Natatoriums: A Case Study
Natatoriums are notoriously difficult facilities to design and construct as there are many important factors to consider that, if overlooked, can result in premature failure of the building systems and/or hazardous conditions for building occupants. With respect to the building enclosure, important design and installation practices will help provide properly performing and functioning assemblies. Several important considerations include:
- Providing a continuous, properly installed roof vapor retarder that connects and seals to the air barriers in the wall assemblies.
- Designing for, and installing continuous insulation in multiple layers to reduce the potential for condensation
- Limiting thermal bridging that typically occurs from structural components or fasteners within the systems
- Limiting penetrations through the enclosure and/or providing proper flashing details when penetrations cannot be avoided
When these design considerations are disregarded, it can result in premature failure of the enclosure assemblies, as evidenced at a recent natatorium project in Montgomery County, MD. The facility, which was constructed in the early 1990s, is divided into five separate and distinct areas, two of which house indoor swimming areas. The roof assembly over the swimming areas was constructed as follows (from top to bottom):
- 24-gauge standing seam, pre-painted galvanized steel roof panels
- 30 lb. roof felt, fastened to the composite insulation board
- Composite insulation board (7/16” OSB factory-laminated to 2-1/2” polyisocyanurate insulation)
- Vapor retarder/barrier
- 1-1/4 exterior plywood sheathing
- Steel deck
These two roof areas experienced severe degradation of the metal roof panels with surface rust noted throughout and large areas of panel corrosion with exposed felt underlayment. The level of corrosion observed in the metal roof panels +/-25 years after construction was unusual and indicated there may be issues with the vapor barrier. The original construction documents followed basic natatorium design principles, which detailed the vapor barrier extending vertically onto rising walls and curbs, following destructive testing, and connecting to the wall air barrier at transitions. However, following destructive testing, it does not appear that these requirements were implemented during construction.
To reduce the possibility of moisture migration into the new roof system, the new vapor barrier was designed to be installed over the existing roof that encapsulated the wood blocking at the ridges, rakes, and eaves and tied into existing curbs and the exterior wall brick masonry. The insulation thickness was increased and installed in multiple layers to meet current code requirements: 30 lb. roof felt was specified under the new standing seam metal roof panels.
During demolition of the existing roof assembly, it was observed that the existing vapor barrier was not continuous at edge transitions, penetrations, or at eight large skylight curb assemblies. The vapor barrier terminated approximately 1/4” short of all rising walls and curbs, providing a path for moisture migration from the interior. Although we could not visually verify if the roof vapor barrier connected the wall air barrier at the ridges, rakes, and eaves, evidence of moisture staining on the existing vapor barrier and degradation of the insulation at these edge conditions indicated these connections were incomplete.
Consistent migration of chemical- and moisture-laden air from the building’s interior due to an improperly flashed vapor barrier was likely a significant contributing factor for the premature failure of the roof assembly. This project serves as an example of the importance of designing and installing a complete vapor to air barrier assembly.
White roofs versus dark roofs? When choosing a surfacing or membrane color, there are several things to consider. White membranes, also referred to as cool roofing, use highly reflective and emissive properties generally associated with lighter colors to reflect solar radiation and, as such, emit heat to reduce roof surface temperatures. Darker membranes absorb heat from the sun, and radiate this heat to both the surrounding atmosphere and the building interior below. Since we can’t turn our roof black in the winter to absorb the heat, and white in the summer to reflect it, how do we know which roof would be better suited for our building’s overall efficiency?
During summer months, when building interiors are typically conditioned (i.e., the “cooling season”), the advantages of a cool roof in terms of cost effectiveness, are obvious – a highly reflective roof reduces heat gain by reflecting solar radiation. Reducing heat gain into the roof system will help reduce cooling costs. This translates to a clear advantage of white roofing in southern climates where the cooling season is most prominent. In summer months, studies have shown that cool roofs can reduce surface temperatures by more than 25%. Currently, ASHRAE Standard 90.1 contains “cool roof” solar reflectance and thermal emittance provisions for Climate Zones 1-3, the warmest climate zones in the United States, but no such provisions are set for Zones 4-8 (see ASHRAE Climate Zone Map below).
North of Climate Zone 3, the debate as to the value of cool roofing continues. Some industry groups and leaders are of the opinion that dark roofing is more efficient in areas where the heating season outlasts the cooling season (due to the potential for an increase in winter heating costs produced by cool roofing). There are several, perhaps less obvious, factors that appear to limit or nullify the advantages of dark roofing in colder climates and winter months:
• Snowfall – Snow can significantly affect the thermal performance of the roof surface, not only through coverage, but also through its insulating properties. Roofs in northern climates can spend much of the winter covered in snow, which prevents the solar radiation absorptivity of a darker roof surface from being useful. Additionally, depending on its depth, fallen snow on roofs can act as an additional layer of insulation, making the roof surface color even less of a factor. As a side note, less snow melt can impact snow load, and this should be taken into consideration during the design phase.
• Solar Angle –The angle of the sun is lower during winter months and the days are shorter, particularly in norther climates. There is less total solar radiation available to be absorbed by the roof, making the benefits of a dark roof less pronounced during the winter.
• Shorter/Cloudier Days – The number of cloudy days historically increases in most northern climates during winter months. The increase in cloud cover reduces the sun’s ability to heat the roof, again diminishing the advantages of dark roofing.
• Energy Resource Costs – In most cases, heating resources like natural gas or oil are less expensive than cooling resources such as electricity, so the added winter heating costs for a cool roof make less of an impact than the added summer cooling costs for a dark roof. Additionally, most heating occurs in early morning or late evening hours, when solar radiation on the roof is low.
There are, of course, situations where cool roofing may not be a preferable option. Buildings in extremely cold climates or certain buildings where cooling is seldom (if ever) used may not draw sufficient benefits from reduced cooling costs. Cool roofing may also be at a higher risk of developing condensation beneath the membrane in consistently cold climates if the roof is inadequately insulated or ventilated.
If you have a building in a southern climate, cool roofing may reduce energy costs. Even in northern climates, a cool roof might be a worthwhile consideration.
Cooperative purchasing is a contracting option for public agencies, such as educational facilities (K-12 and higher ed.) and non-profits, to purchase equipment, products and related services without going through the time-consuming public solicitation process. Contracting agencies (Coops) such as the National Joint Powers Alliance (NJPA) conduct a competitive solicitation process of vendors (for equipment, products, etc.) and once awarded, the vendor is contracted with the Coop at set unit prices. The Coop has already conducted the required competitive bidding process. Once a member of a Coop, schools or other public agencies can purchase from vendors at the contracted unit price, without having to put in the time/effort to conduct their own public bid process.
Cooperative Purchasing can be used by schools and towns to purchase synthetic turf and infill (materials) for athletic field installations, including running track and tennis courts. Municipalities are permitted to request a quote directly from the various coop contracted vendors for their specific products. Using this purchasing mechanism, public sector clients may save money as the costs for various products are often less than when publicly bid. This also allows the municipality to purchase the exact product they want (i.e. turf and infill) rather than settle for a product that may meet a more general public bid specification.
Gale recently assisted a local Regional High School with the purchase of materials through NJPA, the process consisted of the following:
1. Establish membership with a Coop, at no cost.
2. Review Coop’s Contract Directories to view the list of awarded vendors available. (example: NJPA)
3. Contact the vendor directly, letting them know you are interested in using their Coop contract. (Vendors will then provide you with a quote in accordance with their Coop contract and their pre-established pricing).
It was recently announced that the 9th Edition of the Massachusetts State Build Code will be released in August or September 2017. A concurrency period will be provided in which a building can be permitted under either the current 8th or the new 9th edition. This concurrency period will end January 1, 2018 and all projects permitted in 2018 will be required to comply with the 9th edition.
The new, 9th edition code is based on modified versions of the following 2015 codes as published by the International Code Council (ICC):
- The International Building Code (IBC)
- International Residential Code (IRC)
- International Existing Building Code (IEBC)
- International Mechanical Code (IMC)
- International Energy Conservation Code (IECC)
- International Swimming Pool and Spa Code (ISPSC)
- Portions of the International Fire Code (IFC)
The 9th edition brings changes to the building enclosure as well, including but not limited to the following:
- Updated code requirements for location of vapor retarders
- Vegetated roof has been defined
- Load requirements for snow drift load
- Dead load and design requirements for solar panels and support framing
- Provisions for addressing impact loads from elements supporting facade access equipment
- Seismic requirements for ballasted PV solar panels
For more information, click here.
Please feel free to contact Gale if you have questions about how the 9th edition may affect your building enclosure!
The Federal Aviation Administration (FAA) requires all recipients of federal financial assistance exceeding $250,000 in a federal fiscal year (FFY) to create and implement three-year Disadvantaged Business Enterprise (DBE) Programs. These DBE Programs are intended to promote and enforce equal opportunity for disadvantaged firms that compete for airport contracts.
FAA New England Region DBE Programs (FFY 2018-2020) are due on August 1, 2017 and require data collection and analysis to develop goals for DBE participation for upcoming projects. DBE participation goals are calculated based on three major components:
- Available businesses in an airport’s market area for each required area of work (e.g., environmental consultants, paving contractors, or electrical contractors)
- Available DBE businesses in an airport’s market area for each required area of work
- Historical DBE participation data (airport-specific)
The FAA requires approval of DBE Program goals prior to granting federal funds. Below are some helpful resources for FAA DBE Program development:
Running tracks are a paved-in-place system. The base, comprised of a single-compound polyurethane binder and machine-installed SBR rubber granules, is what gives a track its “cushion.” After this step is complete, the track is finished with multiple spray applications of 100% solid pigmented polyurethane and EPDM granules, or an environmentally friendly water-based structural spray.
There are several environmental advantages to using a waterborne structural spray instead of a urethane based spray:
- Low to zero VOCs
- Made without isocyanates
- Reduced chemical exposure
- Reduced odors
- Faster dry times – two sprays in one day
- Less prep work and issues with clean up
- When replacing the track, the reduction of harmful chemicals allows for simpler disposal due to reducing hazardous and environmental liabilities
Many tracks are constructed on land adjacent to environmentally sensitive areas. Choosing a waterborne structural spray for these conditions is appropriate to enhance environmental protection and alleviate concerns about potential chemical exposure.
During a recent Gale track project (photos shown to the right), the town chose to use a waterborne structural spray because of the track’s adjacency to wetlands, a perennial stream, and close proximity to residential neighborhoods.
What is EIFS?
EIFS is an acronym for Exterior Insulation Finish System. EIFS is a non-load bearing, exterior wall cladding system that consists of continuous insulation board attached either adhesively, mechanically, or in combination, to exterior sheathing, which is covered with a reinforced base coat and textured protective finish coat. There are two types of EIFS: the Face-Sealed System and the Drained System. Face-Sealed EIFS is a sealant dependent “barrier system” that is fundamentally flawed due to its reliance on perfect workmanship and material performance to provide a 100% moisture barrier. The Drained System, predominantly used today, includes provision for drainage of moisture via flashings and open vertical planes between the exterior sheathing and the insulation board. This system helps to manage moisture that may enter the wall cavity. EIFS was first developed in Europe and was introduced to the U.S. as an energy-saving building system on commercial buildings in the late 1970s and residential homes in the early 1980s. The EIFS Drained System was introduced in the late 1990s.
Issues with Face-Sealed EIFS
Commercial and residential buildings constructed between the late 1970s and the early 1990s that have Face-Sealed EIFS cladding could potentially have one or more undesirable conditions caused by bulk water intrusion combined with
inadequate wall drainage. Water trapped within this wall system can cause further issues when combined with HVAC deficiencies. Defects can include microbial growth, staining of interior finishes, reduced structural integrity (corrosion and/or decay of load bearing walls), insect infestations, increased interior humidity, and cracking of the interior and exterior finishes. Although these issues are often readily apparent, decay and corrosion can be concealed and may result in latent structural damages.
The noted defects are typically exacerbated at building walls that are not periodically maintained. One of most common causes of moisture intrusion through Face-Sealed EIFS are deteriorated sealant joints and window systems. It should be noted that the service life of most windows is less than 40 years, and the service life of most sealants is less than 15 years. This implies that buildings constructed with Face-Sealed EIFS likely have windows that are approaching the end of their serviceable life, and that replacement of exterior wall sealant joints should have occurred at least twice during that time.
s (microbial growth), and the loss of revenue associated with the construction and abatement (which may include temporary relocation of tenants). If your Face-sealed EIFS clad building has deteriorated exterior sealants (typically crazed/cracked appearance) and/or interior staining/mildew odor, an assessment by an industrial hygienist, building enclosure consultant, structural engineer, and possibly a mechanical engineer are recommended. The assessments should be followed by a structured plan to make necessary repairs and replacements, and periodically (typically every 5 to 7 years) evaluate and maintain the exterior wall and fenestrations.
Deferred maintenance of sealant joints and windows in Face-Sealed EIFS can result in significant construction costs to repair or replace the EIFS, interior finishes and windows, the abatement of hazardous material.
To maintain the aesthetics of a new roof design, building owners often choose to conceal their rooftop mechanical equipment with screen walls. Screen walls are considered “architectural walls,” and are typically constructed using steel frames and finished with metal wall panels.
While aesthetics are an important consideration for screen wall design, building owners and designers should not overlook wind loading while selecting metal wall panels for their screen wall. Metal wall panels are often secured to a solid substrate, such as a masonry wall; however, wall panels attached to exposed steel framing (vertical posts and horizontal channels) in screen wall applications typically leave the back side of the panels open and exposed to wind. Wind can create a negative pressure acting outwards from behind the panel. This wind load pressure can cause panels to bow, allowing the connection between panels to disengage. When selecting metal wall panels for a rooftop screen wall, consider the following parameters:
- Panel Width: Increasing the width of a metal wall panel increases the surface area on which wind loads are applied. Selecting narrower metal wall panels helps to mitigate the effects of negative wind loading pressure.
- Panel Material: Many manufacturers offer metal wall panels in a variety of materials including aluminum and steel. Thicker gauge material with higher tensile strength will reduce the tendency for panels to deform under negative pressure.
- Panel Profile: Metal wall panels come in a variety of profiles: panels typically consist of two engagement legs on either side of the panel that interlock to form a connection between adjacent panels. Panels with longer engagement legs will provide for a deeper connection between adjacent panels, limiting the possibility of this connection to be compromised under wind loads.
Installing metal wall panels on a rooftop screen wall can improve building aesthetics; however, without proper consideration of wind loads, these panels are susceptible to damage. Selecting metal screen wall panels of an appropriate width, material, and profile to withstand wind loading pressure will help the panels to remain secure throughout the life of the roof.
In today’s health-conscious and eco-friendly world, the popularity of organic products is on the rise. This interest and concern has carried over to Athletic Facilities Planning. Gale recently completed a project for a school opting to use organic infill for two new synthetic turf fields. The school was focused on the fields’ proximity to wetlands, as well as the health of their students and the perceived concerns associated with SBR crumb rubber. The school was provided with a summary of alternative infill options and Geofill, a coconut/cork and sand mix, was selected.
The School District felt this decision was appropriate after weighing the pros and cons of the infill options and costs. Below are some considerations for organic alternate infills:
- Organic and environmentally friendly.
- Retain water, which provides an evaporative cooling effect as compared to fields with a crumb rubber infill. This can be an advantage, especially in warm climate locations.
- Provide athletes with a natural feel under foot.
- Shock pads provide a consistent G-max (acceptable impact level).
- The cost is higher compared to traditional crumb rubber field (40% increase for infill and shock pad).
- Can require more maintenance than crumb rubber.
- Requires replenishing every 2-3 years.
- The material is not recyclable for infill use, but can be used for landscaping beds.
- May require watering since it can become dusty during a dry summer.
At one time or another, every building owner will deal with the process of replacing their roof. While this is a necessity for the proper function of a building, it can often be costly, disruptive (smelly and noisy), and messy. If your building currently has a metal roof that needs replacement, one option to consider is a metal roof overlay system.
The most common metal roof overlay system includes prefabricated sub-purlins, which are z-shaped structural members that are factory cut to fit snugly over a variety of metal panel profiles. The purlins, typically 16-gauge galvanized steel, are attached through the existing metal roof panels to the building’s structural frame to provide the appropriate base to which the new metal panels are secured.
The benefits of a metal-over-metal retrofit roof system include:
- Reduced costs and disruption associated with demolition, and provides better protection for the building’s interior finishes from unpredictable weather versus removing the existing metal roof.
- Minimized requirements for the contractor to gain interior access, which reduces interruption of occupant day-to-day activities.
- Increased energy efficiency. The sub-purlins can be formed to customized depths to allow installation of additional insulation.
- Reduced labor costs from faster project completion.
- Ability to easily upgrade an existing exposed fastener (face fastened) metal roof to a more watertight standing seam (concealed clip) roof.
There are many factors to consider before choosing a sub-purlin retrofit system. The existing building structure should be analyzed to verify that it can safely support the additional weight of an overlay. Furthermore, applicable code requirements should be researched to determine if the new overlay system will be compliant. Lastly, the overall condition of the existing metal roof system and insulation assembly should be evaluated. If the existing panels are visible from the interior and are aesthetically unpleasing, or if the need for continuous insulation is driving your roof project, an overlay may not be the right option.
When planning an athletic facility project, it’s important to keep in mind the overall project timeline. Prior to bulldozers and excavators moving dirt, an engineering process that can take months to complete must occur. While each project is different, below is a typical project process and timeline:
The FAA is offering a $500 rebate to general aviation aircraft owners to aid in the cost of Automatic Dependent Surveillance – Broadcast Out (ADS-B Out) equipment. Starting in 2020, this equipment will be mandatory for flying in most controlled airspace.
The ADS-B Out requirement is part of a transition from ground radar and navigational aids to precise tracking using satellite signals. The equipment periodically broadcasts an aircraft’s position, velocity, and other information including dimensions. Displays utilizing ADS-B Out are capable of showing other aircraft in the sky or on the ground at an airport. It can also provide pilots with information on hazardous weather, terrain, and temporary flight restrictions. Only certain features are required by the ADS-B Out 2020 mandate. Title 14 CFR §91.227 defines the equipment requirements.
The FAA plans to issue up to 20,000 rebates on a first-come, first-serve basis for up to one year. This incentive is only for registered, fixed-wing, single-engine piston aircraft. Software upgrades to existing equipment are not covered by the rebate. For additional information on rebate eligibility, equipment installation, and to reserve and claim a rebate, visit http://www.faa.gov/nextgen/equipadsb. A full description of the airspace covered by the mandate can be found in Title 14 CFR §91.225.
The scientists at the National Oceanic and Atmospheric Administration’s (NOAA) National Hurricane Center have predicted that the 2016 hurricane season will be more active than in the last three years. We have learned from experience that hurricanes can be quite unpredictable, causing widespread damage to many vulnerable areas, and are not limited strictly to coastal regions. Depending on the ultimate path and intensity of a storm when it makes landfall, hurricane‐force winds can cause loss of power, flooding, and damaged or destroyed roofs, doors, windows and wall systems. This could lead to substantial interior and or structural damages to buildings. These storm-related building failures can cause unanticipated shutdowns of educational, institutional and commercial sectors within a community.
The following preventive measures may help avoid or reduce catastrophic harm to your building’s components and systems, and improve the chances of your facilities maintaining functionality in the event of a hurricane:
Reliable Back‐up Power & Resources. Stockpile resources, such as generators, batteries (alkaline, rechargeable, car, solar voltaic, etc.), a reliable supply of fuel, water, flashlights, radios, portable televisions, power inverters, roof repair materials, removable shutters, tarps and any other essential items in a secure location where they can be quickly retrieved after the storm.
Protect the Roof. Inspect the entire roof thoroughly before storm season. Secure areas of displaced membrane or perimeter flashings by installing additional anchors, especially in older buildings that have not been designed to meet current wind code requirements. Install additional fasteners or screw anchors with washers on the face of the edge metal or coping face flanges, with the highest priority being at corner zones and about 24‐in. on‐center in the perimeters. Add mechanical fasteners to membranes in vulnerable perimeter areas where adhesion of the roof system is suspect.
Mitigate Stormwater and Flooding Concerns. Remove debris or loose materials that could clog drains, gutters, downspouts and scuppers to maintain free flow of water. Relocate or reposition critical materials, such as scientific experiments, records and archives, key computers, etc., away from areas that may be prone to flooding.
Secure Roof Appurtenances and Accessories. Basically, anything that is anchored to a roof needs to stay there. Reinforce or secure air‐conditioning equipment and fans to the roof using additional screw fasteners and/or straps. Add metal or even nylon straps at strategic locations to help reinforce the ducts and provide supplemental anchorage down to supports.
Safeguard the Building Enclosure. Minimize potential damage from windborne debris and to the building’s exterior by using storm shutters (preferred method), plywood panels, steel deck material or lightweight corrugated plastic materials to protect windows, doors and louvers (wall openings). Window films applied to the inside of the glass can provide a level of protection, but its use should be limited to upper floors, as films are generally not tested for large projectile resistance. Secure or bring in light-weight objects, such as garbage cans, tools or furnishings that may become projectiles during a storm.
Implement a Facility Survival Plan. Creating a plan before the storm will help you to quickly mobilize and make necessary repairs to restore operations as soon as possible. Below are some important steps to consider:
- Establish a base of operations from which to coordinate recovery and repair efforts.
- Develop a contingency plan that focuses on readiness, including manpower, equipment and materials needed immediately after the storm.
- Organize a recovery team by assigning repair tasks to specific individuals or contractors prior to the emergency. Include team member phone numbers and email, as well as team staging and assembly locations. For each roof or wall assembly, specify materials, protocols and personnel responsible to address problems. Use a chart or calendar to establish a timeline for required repairs. A repair manual will also be helpful and allow for consistent quality standards during the recovery operation. Roof and wall repairs should be completed by a contractor knowledgeable about proper flashing techniques and materials.
- Develop a primary and backup communication protocol with post-event procedures for on-call constructors, consultants or other entities to expedite emergency assessments, evaluations and repairs; to temporarily relocate assets or functions; and for potential transportation needs.
Did you know that a half-inch space is all a bat needs to crawl into your roof? A space the size of a bottle cap is all it takes for them to begin causing havoc. The presence of bats in a building can affect the replacement process and add costly repairs in an existing building.
Some species of bats are endangered and protected, while others are just disruptive. It is important to consider how to resolve the problem of evicting them from the habitats they create in your
structure, and to understand the laws in place to protect
them, and what measures must be taken to relocate them.
Bats are an important part of our ecosystem. They consume a vast amount of insects including some that damage agricultural crops, they
pollinate valuable plants, and their waste can be a rich natural fertilizer;
however, bat guano in your building is not pleasant and can be environmentally hazardous.
One major issue bats can cause is staining in the area they enter and exit a facility. This is due to waste accumulation, and can ruin building insulation, sheet rock or particle board, cause an unbearable smell and in extreme cases may cause structural damage.
Tall structures are ideal locations for bats because higher elevations are less likely to receive maintenance. Facility owners seldom notice small cracks or gaps on the facades of higher buildings, but that half inch crack in a mortar joint 30 or 40 feet off the ground can become a highway for bats to enter a structure. Once they gain access to your space, getting them out is a costly and a time consuming endeavor and depending on the location, it can interfere with day-to-day operations.
Because some bat species are protected, a professional should be utilized in the removal process in order to relocate them to a safer area that does not cause harm to you or the environment. Usually this is done through a process called bat exclusion, which lets them fly out, but not back in. This process is performed at night when bats leave to find food. A professional will need to determine the proper enclosure required repairs to prevent them from coming back and assist in the preparation of a maintenance program.
Inspecting your building and knowing what to look for is a crucial step in maintenance and avoiding this problem. At a minimum, become aware of what natural habitats are present in your surroundings. This will help determine what kind of inspections are required. Some important points to consider are:
• Training maintenance personnel on the warning signs of bats
• Incorporating a systematic documentation process to know what to look for on a daily, weekly or monthly basis
• Communicate any bat findings with professionals trained in the relocation process
Once bats or other critters find their way into your building, many issues can arise. Not only do you need to get them out, but the clean-up can be tedious. Next time you spot that small “insignificant opening” in your building, don’t ignore it, you never know what’s inside or what species wants to make it the entrance to their new home!
Take some time to view the links below for more information:
Many involved with aviation are aware that pointing lasers at in-flight aircrafts can be a serious, if not deadly, issue. The FAA and the justice system have been taking serious action against violators of FAA policies banning the practice of striking aircraft with lasers. Violators are given heavy jail sentences upon conviction (a 26 year old man in California was sentenced to 14 years in federal prison), and the FBI is currently offering a $10,000 reward for information leading to the capture of a recent violator.
Click here for additional information on this serious subject. This FAA page includes articles detailing laser-related arrests and convictions, an FBI video on the dangers of pointing lasers at aircraft, and a consumer safety alert on purchasing lasers.
New England winters, as evidenced by 2010/2011 and 2015, can deposit large amounts of snow on roof areas and potentially overload the roof structural system. Snow tends to accumulate against rising walls and parapets, rooftop units and roof wells, and can cause large concentrated loads on roof areas. Original building structural drawings often express the snow load that the roof was designed for in pounds per square foot (psf). This doesn’t directly correlate to a depth of snow. The allowable depth of snow depends both on the design load psf and the unit weight of the snow in pounds per cubic foot (pcf). The Massachusetts State Building Code (MSBC) and associated references provide an equation for the unit weight of snow based on the design ground snow load; however, the actual conditions may vary depending on the weather.
We suggest the following procedure for measuring roof snow loads:
1. Measure the depth of snow at various locations around the roof area. Pay particular attention to accumulated snow against rising walls or mechanical units where snow tends to drift. We recommend using a plastic shovel to dig down to the roof system to avoid damage.
2. Using a known volume such as a stove pipe of known diameter and height, obtain a sample of snow in its existing condition. A stove pipe can be used to slide through the snow and then cap the bottom of the pipe to collect the snow.
3. Measure the weight of the sample snow (remember to subtract the weight of the stove pipe or similar apparatus).
4. The unit weight of the snow will be determined by dividing the weight of the snow by the known volume. We suggest performing the measurements at multiple locations on the roof, including where the snow appears to be consistent depth and at drifted snow locations as the unit weight may vary.
5. Once the unit weight is obtained, divide the allowable uniform load (obtained from the original drawings) by the unit weight to provide an allowable snow depth. For example, if the design or allowable snow load is 30 psf and the unit weight of snow is 20 pcf, the allowable snow depth will be 30/20 = 1’ 6” of snow.
6. While performing the measurements, be aware of any ice, slush or water below the snow since these are generally heavier than the snow. These layers should be weighed separately and added to the snow load.
An important first step in completing an athletic campus needs assessment and master plan is the sampling and agronomic testing of fields’ root zone materials to evaluate soil structure, organic content, micronutrient levels and pH. Testing is a key factor in developing the proper maintenance or rehabilitation strategy for improved turf growth.
Over the years, Gale has observed a significant trend in our testing results. Athletic fields, particularly in northern New England, tend to be more acidic. These fields must be maintained to hold up under substantial use, requiring considerable planning and maintenance to sustain their soil quality. Over the past two years, we have documented and recovered soil samples with an average pH of 5.2, and with individual values below 5.0. This significant level of acidity results from the gradual breakdown of indigenous plant materials in the soil, and is exacerbated by the influence of acid rain.
Why should we be concerned with this?
According to the Massachusetts Natural Resources Collaborations (Mass NRC), the pH of the soil directly affects the amount of nutrients available to grass cultivars. Cultivars are varieties of plants produced in cultivation by selective breeding. They can ingest the wrong nutrients when pH levels are not optimal. Preferred nutrients are most accessible when the pH is in the range of 6.0 to 7.0. With average pH ranges consistently below 5.5, regardless of the fertilizer regimen, turf grass is often starved. For example, Kentucky Blue Grass blends, often selected for athletic turf grass based on their restorative capacity due to their rhizome generation, cannot prorogate as intended and fields break down under normal use.
How can we fix the issue?
Lime! The UMASS Department of Agronomy provides specific lime application strategies for each soil sample tested. While there are multiple considerations for crafting a pH adjustment strategy, low pH root zones with values less than 5.4 generally call for lime application rates of up to 150 pounds of limestone per 1,000 SF, applied at a rate of no more than 50 pounds per spring or fall season. For a typical 90,000 SF multi-purpose rectangular field, this amounts to 4,500 pounds per season for three consecutive seasons. In summary, test the soil and be prepared to apply lime for a happier, healthier natural turf field.
Glazed aluminum curtain walls are engineered and tested more than any other type of building enclosure system. Unlike most fenestration and cladding assemblies, curtain walls are an assembly of parts designed and detailed to achieve project specific performance and design requirements. Since they are performance driven, the designer needs to define performance criteria as it relates to evaluating, engineering, testing, production, construction, and commissioning of the curtain wall. There are a number of environmental, maintenance, performance, and security/safety factors that need to be considered when selecting a system. These factors include, but are not limited to, determining structural loads/movements resulting from wind and seismic forces, maintenance access equipment and operations, temperature change, and external/internal loads imposed on the supporting building structure. Performance considerations include thermal value, air and water infiltration, condensation resistance, and acoustic separation. Based on the building location and usage, safety considerations may include fire resistance, airborne missile protection, blast protection, and falling ice protection.
There are several types of curtain walls available from which the designer can choose among. Most systems fall into two classifications: stick frame and unitized. Stick frame systems are usually delivered to the site in parts and built in place. Some systems can be partially built off site and delivered to the site. These “ladder frames” are typically spliced together, leaving a joint in the interior face of the mullion. On the other hand, a unitized system is completely assembled in a factory, delivered to the site, and hung on the building. A unitized system can speed installation and avoid problems associated with field installation and weather but can come at a higher cost and need specific attention to air and water-tight integrity at panel to panel connections. In order to select a system, the designer must also identify if it is inside or outside glazed and the thickness of the glazing, as each system will have different limitations. This selection must consider the building as a whole. For instance, you would not want to select an interior glazed system if there were structural steel elements that may interfere with the installation.
Once a system is selected, the designer must also specify an assortment of add-ons and custom components. Glazing can be specified as captured or with butt joints utilizing structural sealant. Captured glazing systems use a pressure plate to hold the glass in place. These plates come with standard flat snap-on covers but a projecting or shaped cover can be used. Gaskets can be dry or wet sealed, and may consist of silicone, silicone rubber, EPDM, or neoprene. Setting blocks and anti-walk inserts should also be considered depending on the application. Another important accessory is the transition flashing that connects the curtain wall to the adjacent wall construction. While there are several options, the preferred option is a pre-cured silicone transition membrane that can be set into the glazing pocket and span the rough opening gap to the air barrier. Since this membrane can be installed by the waterproofing sub-contractor or curtain wall installer, coordination of the products for compatibility and sequencing is important.
The project specifications should clearly identify each of these accessories and each project performance requirement. Relying on manufacturers’ recommendations, which are often price driven, may not provide real world performance values. Most manufacturer data is based on standard unit sizes and glass types, and does not take into account actual job specific materials and layout. Project specific modeling and testing is recommended to confirm anticipated performances. For this reason, it is recommended that owners and design professionals use a building enclosure professional with curtain wall experience to assist the team through the labyrinth of curtain wall specifying.
Vehicle safety at the airport, it seems so simple. Just drive carefully, right? Not exactly. Yes, it is important to drive cautiously in an airport environment, but there is more to consider than your own driving skills, such as:
- Understanding signs and pavement markings
- How and what to communicate to Air Traffic Control or nearby aircraft
- Proper radio communications, finding a safe place to park, familiarity with a particular airport’s environment
- Respecting adverse weather and visibility conditions
The FAA has published two useful documents on this topic. The first, FAA Guide to Ground Vehicle Operations, is a short, comprehensive guide. The second, Advisory Circular (AC150/5210.20A), was released this past fall and includes information on vehicles taxiing or towing an aircraft. These documents have straightforward and valuable tips on how to drive safely in an airport environment. They can also be useful in developing airport rules and regulations.
It’s that time of year again!
If the upcoming winter is going to be anything like last year, now is the time to begin preparing your site for upcoming inclement weather. Snow and ice can make for a treacherous drive or walk through parking lots and sidewalks. Follow these tips to reduce potential site hazards this winter:
- Check for low spots that could collect water and create potential icing hazards.
- Clean catch basin grates and sumps, clear away leaves and make sure the structure is stable and sound.
- Beehive grates on catch basins can help to prevent clogging in non-paved areas.
- Ensure gutters are clean and there is no clogging of underground systems.
- Maintain outlets (flare ends, headwalls, etc.) to ensure positive flow.
- Ensure there is proper curbing and guard rails to prevent sliding off of the road.
- Provide clear signage for traffic and pedestrians.
- Ensure bricks/pavers are set flush for easy shoveling/snow blowing.
- Create designated snow storage areas.
- Delineate edges of pavement and curbing to keep plows on the traveled way and out of landscape islands.
When we hear the words historic preservation, notions of “antique” often come to mind. Boston’s Old State House (c.1713) and the Washington Monument (c.1848), both recently restored, reflect true history in both their age and their cultural importance. Although the iconic Chrysler Building in New York City (c.1928-30) is from a much later era, it similarly reflects the cultural significance of 1920’s architecture.
Buildings constructed in the 1920s are approaching their 100 year mark. In many cases, their durable enclosure systems (commonly masonry, steel framing, wood, and glass) have lasted with minimal, if any, maintenance. Due to age and deferred maintenance, these materials may be beyond their anticipated life cycle, resulting in a range of problems that, if left unaddressed, may result in life safety issues, disruption of building occupancy, and increased repair costs.
A sampling of 1920’s enclosure component issues that must be addressed include:
- Transitional Facade Construction. This construction style incorporates a steel or concrete structural frame with masonry back-up and infill. Masonry and concrete often encase the structural steel frame. Deterioration problems may be associated with a lack of detailing to accommodate differential movement (resulting in cracking), and reliance on the “mass” of the exterior masonry wall to prevent water infiltration and exfoliation (corrosion) of the embedded structural steel and resultant cracks and spalls. All must be addressed in any ongoing restoration project.
- Misconception that Masonry is Maintenance-Free. In the 1920s, masonry was often seen as a high craft. However, even with the best materials and workmanship, it requires maintenance. The service life of mortar joints is about 50 years, after this time repointing is often required. Without such maintenance, open joints will allow moisture into the wall assembly, resulting in accelerated damages to backup walls and increased repair costs.
- Lack of Energy Efficiency. Improving energy efficiency inside the enclosure of this older stock of 1920s-era buildings requires technical consideration for the type, thickness, and placement of vapor barriers. Adding insulation to the interior face of exterior walls, if not adequately designed, can result in accelerated deterioration of the masonry and can lead to mold and water infiltration issues.
- Original Windows and Doors. While original, uninsulated windows and doors contribute to the heritage of the building, they also contribute to poor thermal performance, experience deterioration or corrosion of the frames, or become inoperable. If replacements are necessary, they can be done in a way that maintains the historic qualities of the building while improving the overall energy efficiency.
Many 1920s buildings are either on the State or National Register of Historic Places, or certainly have enough historic value to be considered candidates. The Federal Government’s published guidelines, such as The Secretary of the Interior’s Standards for the Treatment of Historic Properties, are among the tools available when considering restoration.
As this group of buildings rises in historic importance, any deferred maintenance should be addressed. These valuable buildings deserve repair and restoration that will allow them to endure another century and beyond.
Did you know that one of the major contributors to building leakage is when the draining system becomes obstructed?
Trees, dusty areas, and high wind prone locations can affect your roof and gutter systems. Falling leaves, branches, acorns, twigs, and insect and bird debris can accumulate around drain strainers and in gutter boxes, allowing water to pond on the roof. Leaves that block a drain strainer can allow up to six inches of standing water.
Standing water can then leak through small imperfections in the roof, which may be caused by wind scour from wind borne debris, imperfections in the flashings, or damages resulting from routine maintenance and/or walking on the roof. Once these obstructions begin to add up, they are compounded by additional debris, and windblown dirt and dust which can become captured within the standing water.
Although it seems unlikely, water in your basement or walls can often be attributed to gutter and drain issues. The intent of a gutter is to collect stormwater from a steep sloped roof, and direct it to a downspout. If the downspout or gutter box is filled with leaves, water can potentially sit in the gutter box. This adds weight to the gutter box, and can cause the gutter supports/anchors to become loose and pull away from the wall, or twist. Water can then drain to unprotected areas below, and often can find its way to the building’s foundation system. During winter months, poorly draining gutters can freeze and may contribute to ice dams.
Since it only takes minutes to clean debris from drains, gutters, and downspouts, we recommend that these areas be cleaned prior to winter and following spring to reduce the potential for leaks and building damages which may result from improper drainage.
The roof perimeter edge is one of the most critical components of a roof system when considering wind resistance. It is the first line of defense against catastrophic roof blow-offs, where increased wind uplift pressures occur due to building aerodynamics, particularly in corner locations. Oftentimes overlooked during the design of roof replacement projects, the as-built conditions of the existing perimeter edge must be investigated and examined to determine compliance with building code requirements and association industry standards. Traditionally, the roof perimeter edge consists of multiple layers of continuous 2x wood blocking with end joints staggered and fastened together with annular ring nails or bolts. The fasteners used for anchoring the wood blocking to the roof structure are typically post-installed and vary between adhesive or mechanical anchors depending on the material of the substrate. The anchors at the roof perimeter must be able to resist tensile forces due to wind uplift, shear forces due to wind loads acting perpendicular to the axis of the anchors, and the combination of both forces acting simultaneously. Listed below are a few guidelines when designing or installing anchors for roof perimeter wood blocking:
- Verify the material and condition of the substrate at the roof perimeter to ensure that the anchors are fastened to a sound, structural element of the roof deck.
- Spacing and embedment depth of the anchors should be designed to ensure that the anchors provide adequate resistance to wind uplift and other applicable loads; reduce the anchor spacing at the corners of the roof.
- When the width of wood blocking is greater than six inches, the spacing of anchors should be staggered in two rows across the width of wood blocking. Countersinking of bolts on the lowermost wood blocking must be avoided due to reduced pull-through resistance.
- Verify that the material of the anchor is compatible with other components such as edge metal fascia to prevent galvanic reactivity.
- Wood blocking must be continuous at all layers and adequately sealed to prevent air infiltration beneath layers of wood blocking.
The Community Preservation Act (CPA) enables participating communities to set aside tax revenue and matching state funds for preservation of open space, creation of affordable housing, and development of outdoor recreational facilities. Over a decade of work went into creating the CPA, which was signed into law on September 14, 2000. Click here for more information.
Through the CPA, communities create a local Community Preservation Fund that is raised by imposing a surcharge of less than 3% of the tax levy against real property. Municipalities must adopt the CPA by ballot referendum. In its first 15 years, the CPA has achieved the following:
- 158 communities have adopted the CPA (45% of the Commonwealth’s cities and towns)
- Close to $1.4 billion has been raised to date for community preservation funding statewide
- Over 7,500 projects have been approved by local legislative bodies
- Over 8,500 affordable housing units have been created or supported
- 21,838 acres of open space have been preserved
- Over 3,600 appropriations have been made for historic preservation projects
- Nearly 1,250 outdoor recreation projects have been initiated
Amendment Allows for Rehabilitation
An important amendment passed in April 2012, allowing cities and towns to use CPA funding to rehabilitate existing parks, playgrounds and athletic fields, rather than only build new ones. This has afforded participating towns far more flexibility in their use of CPA funding, and has provided an added incentive for new communities to join the CPA program.
One of the caveats of the 2012 legislative amendment prohibits using CPA funds to purchase synthetic turf. Given the increasing popularity of infilled synthetic turf fields as a lower maintenance option to increasing athletic field demands, this restriction has had serious implications for many community projects.
The Use of CPA Funds for Infilled Synthetic Turf Fields
Fortunately, within the past 18 months, several Massachusetts communities found the means to complete significant athletic field developments using CPA funding, with one or more of the fields incorporating infilled synthetic turf. The 2012 amendment stipulates that CPA funding cannot be used to purchase synthetic turf. Gale is aware of several communities that have sought and received legal opinions regarding the exact scope of this restriction.
The state has been consistent in its interpretation of the “no funding for the purchase of synthetic turf” prohibition, and it is literal. It is broadly
accepted that the infrastructure for the infilled synthetic turf field, including materials and labor for installation of the perimeter concrete anchor curb, the formal underdrainage system, and the stone base on which it is installed can be funded by CPA. This accounts for approximately half of the cost of a typical synthetic turf field installation.
To comply with this CPA requirement, we have been involved with several public projects for which local, non-profit booster groups have solicited bids for the turf materials and installation using private funding. Once the purchase was made by the boosters, the materials and their installation were then gifted to the public owner (town or school district). These materials were installed by the turf company under contract to the boosters, over a base constructed by the athletic field general contractor, and paid for with CPA funds. One possible downside to this procurement strategy is the division of the construction between the general contractor funded by CPA and the privately funded turf installation, leading to split liability and responsibility for the resultant surface.
More recent interpretations also substantiate that CPA funding can be used to install the synthetic turf carpet, infill, and markings. As a result, if an infilled synthetic turf field costs an estimated $900,000, all but the actual purchase of the synthetic turf carpet and infill materials can be funded using CPA funding, leaving about $200,000 (the approximate cost of the synthetic field carpet) to be financed using some other source, either public or private.
In one municipality, a local non-profit private booster group solicited bids for the turf and infill materials using private funding. Once the purchase was made, the materials were then gifted to the public owner to be installed by the athletic field general contractor, paid for with CPA funds. Additional advantages to privately purchasing turf materials is the ability to write a proprietary specification for the exact turf system intended (not allowed under Mass Public Bids Laws), and savings related to the avoidance of a general contractor mark-up.
It doesn’t matter what management practices are in place, the fact remains that wildlife and aircraft will share the facilities and skies. To minimize the risk of incidents involving damage to aircraft, and possible loss of human and animal life, airport operators should remain aware of conditions attracting and repelling wildlife at their airports. Wildlife management is a dynamic, ever-changing field with innovative new products and technologies continuously being introduced. The FAA’s Wildlife Strike Database lists thousands of strikes each year on and around airports due to wildlife incursions into operational areas. Airport operators can increase aviation safety by using strategic, effective management practices and observing the effects on wildlife. To determine which practices could best suit your airport, operators should take note of several critical factors regarding wildlife:
- What are these animals doing that make controlling them necessary? And why are they attracted to your Airport? Control is necessary when animals pose a hazard to aircraft, either on the ground or in the air. Animals are typically attracted to your Airport to satisfy basic needs for food, water or shelter. Identifying why they are at your Airport is an important element in finding an effective solution. For example, if birds congregate in the infields to eat grubs, insects, or edible plant matter; they can be discouraged by using special fertilizer products that, when ingested, cause slight sickness and natural aversion to that type of food. This will result in them vacating the premises – often permanently. So, knowing what animals are doing and what attracted them is important to finding an effective solution.
- What species of wildlife are causing the problem? Accurate species identification will enable operators to select management practices that are specific to that species. The objective is to control the target wildlife, not all wildlife in the area.
- What are the daily and seasonal movement patterns of the wildlife, and what are the synergistic effects from the surrounding land uses? An example of a synergistic effect of surrounding land uses causing wildlife movement patterns is having wetlands, lakes, or other nesting habitat on one side, while on the other side of the airport is foraging land, such as restaurants, farms, parks, grocery stores, wastewater treatment plants, landfills, or other wildlife attractants. Periods of activity usually occur in the morning or evening when wildlife will move from nesting to foraging areas.
Controlling the Wildlife
Each airport has its own unique wildlife, and should attempt to tailor practices and operations to address them. Once observations have been recorded, it is prudent to develop a wildlife control plan. There are five principle methods for controlling wildlife:
- Avoidance – Airport operators may modify operations during times of increased wildlife movement. Although this practice is generally not practical on larger airports with scheduled commercial traffic, general aviation airports will have times when this practice can greatly reduce the risk of incidents. Additionally, temporary runway closures can provide time to disperse the animals.
- Habitat Modification – any action that reduces or eliminates wildlife’s ability to find food, water, and shelter will likely reduce wildlife hazards. These practices are generally well accepted by the public and minimize the need to harass or harm the wildlife. Reducing the amount of food on or near airports can be accomplished by promoting bird-proof refuse containers, prohibiting the feeding of birds, and promoting good sanitation and litter control programs. Large expanses of open areas at airports also provide habitat for insects and small rodents that attract birds of prey. Taking measures such as mowing and use of insecticides, herbicides, and rodent repellant can minimize risks. Birds also use wetlands and marshes with good vegetative cover as nesting grounds. A good way to reduce their attractiveness is to use vegetation that is undesirable to wildlife. There are varieties of fescue grass that contain fungal microorganisms which are unpalatable to grazing birds, rodents, and deer. Piles of construction debris and discarded equipment also attract wildlife because they provide excellent cover for rodents and coyote. Standing water is also a strong wildlife draw. Where possible, areas that collect water during rain events should be filled or modified to facilitate drainage.
- Exclusion – If food, water, or cover cannot be eliminated by habitat modification then actions can be taken to cut off access from these areas. Perimeter fencing can be used to keep animals off airport grounds and anti-perching devices can be installed on ledges, roof peaks, rafters, signs, posts, etc.
- Repellents – Repellents and harassment techniques are intended to make areas where wildlife congregate more undesirable. These practices deter animals by chemical, audible, or visible aggravation; however, acclimation to repellents is a major problem. To effectively employ this type of deterrent, there are a few factors to consider. What type of wildlife needs to be repelled? Is the Airport properly equipped to deploy these types of control measures? Do you understand the movement patterns of wildlife? It’s important to consider a variety of different repellent techniques to minimize acclimation. Use repellents sparingly when the target wildlife is present and only use products approved by the USEPA, FDA, and State Environmental Agencies. Reinforce repellents with occasional lethal control where appropriate. Examples of repellents include:
- Polybutenes – this repellent make birds uncomfortable when they land on a surface that has been treated because it is sticky and irritating, thus causing birds to look elsewhere to perch.
- Methyl Anthranilate – this repellent has an artificial grape flavoring used in food and beverages. Birds have a taste aversion to this type of flavoring and consequently with food sources treated with this flavor. Standing water may be treated with this chemical to deter birds from drinking and bathing in it. This type of practice is best used in temporary pools of water after rainfall, since only a few days of repellency is required.
- Anthraquinone – this chemical is applied to grounds where birds and other animals forage for food. Birds ingesting this chemical become slightly ill and develop post-ingestion aversion to the treated food source. Birds eventually associate the color of the plant with the sick feeling and avoid the treated food source. Treat areas where birds are grazing, and the effects will apply to all areas where that plant is present.
- Propane Cannons and Pyrotechnics – these methods produce loud blasts which sound like firearms but birds tend to acclimate quickly and it becomes background noise to them. This practice should be used sparingly in conjunction with lethal or other practices.
- Taxidermy Mounts – replicas or real animal mounts of predators can be helpful in scaring wildlife away from critical areas by producing a “scarecrow affect.” Hawk effigies, stuffed coyotes, and Mylar-reflecting silhouettes have shown to be effective for a short period of time. Radio-controlled model aircraft can also be used to provide both visual and audio stimuli that repels birds.
- Live Trapping – Specialized traps, drop nets, and snares will help to capture live animals and relocate them to other areas off site.
- Lethal Controls – These types of management practices are generally frowned upon by the public. These should only be used when all other methods have been exhausted, and should be replaced by a long-term, non-lethal solution.
Of the management practices discussed in this article, the most critical and often overlooked factor in ensuring success of a management program is to employ motivated, trained professionals who are knowledgeable in the management of wildlife, and understand the circumstances at your airport that can cause wildlife hazards.
Additional information on wildlife hazard management:
Provides information on the FAA Wildlife Strike Program, the FAA National Wildlife Strike Database, agencies and organizations having jurisdiction over wildlife, federal regulations and policies impacting wildlife management, identifying wildlife hazards at airports, developing Wildlife Management Programs, evaluating Wildlife Management Programs, training for Wildlife Management Program personnel, and wildlife control strategies and techniques.
Provides guidance on certain land uses that have the potential to attract hazardous wildlife on or near public-use airports. It also discusses airport development projects (including airport construction, expansion, and renovation) affecting aircraft movement near hazardous wildlife attractants.
Selecting the right cover board for your single ply roofing application can have a major impact on performance and longevity of the system. Cover boards provide several purposes within a roof assembly including:
- Insulation protection (against crushing) and thermal improvement
- Strength and durability (hail and impact protection)
- Fire resistance
- Sound resistance
- Dimensional stability of the insulation system
In March 2000, the National Roofing Contractors Association (NRCA) endorsed and recommended the use of cover boards over polyisocyanurate insulation, which superseded previous NRCA Technical Bulletins and revisions on the topic, dating back to 1978.
There are several cover board options for single ply roof assemblies, each with their own sets of pros and cons. Four main types of cover board materials for single ply roof systems include glass-mat faced gypsum, fiber-reinforced gypsum, high density polyisocyanurate and wood fiberboard. The pros and cons of these four main types are described below:
Understanding the differences in these materials will contribute to the success of the design, installation and performance of your single ply roof system. All roof systems present unique challenges to achieving a long lasting, thermally efficient building covering. For specific assistance in selecting the material that is appropriate for your roofing application, contact Gale Associates.
The use of synthetic turf is extremely popular, not because of the aesthetics or playability, but for the increased field usage synthetic turf can sustain. A properly scheduled natural turf field can be used approximately 200 times per year without significant degradation of quality. Comparatively, a synthetic turf field can sustain at least twice the amount of play without sacrificing quality or increasing maintenance costs. This increased usability can eliminate the need for owners to construct and maintain additional natural turf fields to accommodate the usage demand. Synthetic turf also can be used in almost any weather, and can take the pressure off of facilities managers to decide if a field is too wet for play. Without an NFL-sized budget, natural grass cannot be maintained in playable condition with such intense everyday use. This is especially true now that most states and municipalities restrict the use of irrigation, pesticides, herbicides and fertilizers on public properties.
Click here for tables that highlight the many choices that must be considered when choosing between the various infill materials available for turf.
With the incredible amount of snow we have received this year, especially in New England, it is important to have a plan in place to remove snow from your synthetic turf field in a careful and timely manner. Snow removal plans are crucial for avoiding delays to spring sports and costly repairs for damages related to improper removal. Below are some important factors to consider when creating a plan:
Logistics. Managing snow removal operations from a turf field requires a logistical procedure to protect the safety of the field, exterior equipment, and site amenities. Do you have a track or trench drain that circumscribes the field? If so, make sure the drain is clear of snow or ice to allow drainage when the snow melts. Also, prepare the turf curb for equipment to navigate over the lip. Use plywood or a manufacturer approved material to create a flush condition at the curb lip. This is especially important for maneuvering larger pieces of equipment
Whom to hire? If you don’t have trained operators or the proper equipment in house, ask your turf manufacturer for their recommendation. Manufacturers typically have a list of reputable contractors they recommend for the work. Be sure to hire a company with both field and plowing experience. While some contractors may have experience with synthetic turf fields, this does not mean they are experts in plowing snow. Claims occur every year from faulty plowing operations for areas on and off the fields.
Equipment and Vehicle Circulation. Use of Low Ground Pressure (LGP) tracks is highly recommended. Snow blowers are also an option if engineered for the job at hand. Bulldozers, dump trucks, and any large pieces of equipment should not be allowed on synthetic turf fields. Equipment that can exert a large concentrated load (over 300 pounds per square foot) on the field, and has the ability to turn sharply is a concern for the stability of the base. Repair of the base (the material located beneath the turf carpet) would most likely require removing the synthetic turf and infill material and re-grading that area. Be aware of the possibility of creating divots or depressions beneath your turf field. Vehicles should be inspected prior to each snow removal operation to make sure they aren’t leaking since leaks can cause permanent staining and/or breakdown of turf fibers. Vehicles should only be allowed to turn on a wide radius or when in forward motion, and should not be left idling or unattended since the exhaust could singe the turf fibers. Sudden braking and sharp turns can cause damage.
Buffer the blade. Many turf manufacturers describe proper methods used to plow fields within their maintenance manual. Attaching a PVC pipe to the bottom of the blade of a typical snow plow is often used. This allows a rounded edge so the blade doesn’t dig into the infill or make contact with the turf backing. It is highly recommended that the bottom edge of the blade is elevated by 1” – 2” above the top of the infill material to eliminate any chance of contact. If the blade is left untreated (no PVC pipe), or is allowed to make contact with the infill, there is a significant risk of transporting the infill to other parts of the field or even off-site with the disposal of the snow. When snow is wet, the underlying infill material and crumb rubber tends to cling to the snow above it. The bottom 1” of snow should be left to remain on the field during removal operations. Any remaining snow (approximately 1” deep) from plowing operations will melt off on the next sunny day.
Use a snow thrower or snow blower. Some companies have state-of-the-art equipment specifically designed for removing snow from synthetic turf surfaces. Snow throwers are becoming popular, especially for fields that have limitations due to perimeter fencing. Snow throwers can launch snow up to 70 feet. This may be of interest to owners who have a running track that circumscribes their field. Some snow blowers also have 1/2” high skis to make sure the blade stays elevated above the synthetic turf surface.
Load Limits. When initiating snow removal operations, make sure to consult your maintenance manual for information about load limits. Many turf manufacturers recommend a static or stationary load not to exceed 300 pounds per square foot. Manufacturers also recommend a rolling load limit of no more than 30 pounds per square inch, which accounts for ambulances or general maintenance vehicles that may visit the field. Unusual heavy loading can result in settling or rutting of the base material. This is especially true for snow stockpile areas. Permanent depressions can result from the heavy weight of snow. An 18” depth of snow over the footprint of the field can result in loads of approximately 31.5 pounds per square foot, or more. This amount of load is not a concern for the field, but when snow is stockpiled in an area and blended with ice or supplemented with rain, a pile of snow, water and ice mix could exert over 300 pounds of force per square foot!
Avoid Accumulation. Snow accumulation of more than a few inches becomes unmanageable for smaller pieces of equipment, such as pick-up mounted plows, that may be used for plowing operations on your synthetic turf field. Another problem is the formation of ice when snow begins to freeze/thaw. Any snow left standing on your field will freeze to an icy consistency as water is drawn out from the snow. If large storms are anticipated, your field should be plowed in 4’’ – 6’’ increments as needed.
Ice Removal and Chemical Treatment. Unlike powdery snow, ice causes many dilemmas for removal from synthetic turf surfaces since it prohibits the use of plows, snow blowers, and snow throwers. Though not all of the turf manufacturers’ maintenance manuals outline chemical treatment options, some recommend using calcium chloride for treatment of ice. Calcium chloride will leave a temporary residue on the turf’s surface and infill that will fade with time. Other manufacturers recommend spreading a pilled fertilizer grade urea at a rate of 100 pounds per every 3,000 square feet.
Cleaning up in the spring. After completing all of the plowing and snow blowing, there will need to be some touch-ups. Snow removal, regardless of how meticulous, usually leads to unbalanced areas of infill within your field. Sometimes unbalanced areas of infill require an industrial sized rotary brush or power brush to move the infill in large quantities over large distances. This would require more effort than typical field grooming operations. Many turf manufacturers or installers offer advanced care services that include final snow or ice clean up, as well as brushing and grooming the field in preparation for spring sports.
Plowing gone wrong. As an industry, we’ve learned from prior failures and developed standards and guidelines to prevent the likelihood of undesirable conditions. When infill material is removed from the field during snow removal operations, it is often left to maintenance staff to clean it up and remove it from the site. This results in a signifant depletion of infill from the turf playing surface resulting in compromising field performance and longevity. It is also very costly to replenish any lost infill as a result of poor plowing.
Remember, having a plan in place before the snow starts falling is the best way to avoid potential delays to spring sports and damage to your field. It you need assistance, contact Gale or consult your turf manufacturer.