December 28, 2018
by Mike Fischer
Construction specifiers are expected to provide a high level of service to building owners by recommending products best suited to meet the aesthetic criteria of a particular project. To compete effectively for projects using steep-slope roofing, a professional specifier should be well-versed in one of North America’s most popular roofing choices: asphalt shingles.
On a job-by-job basis, architects and specifiers need to listen carefully to what owners (both commercial and residential) want and need, and share their expertise by identifying, recommending, and delivering products to satisfy those requirements.
In today’s marketplace, owners should feel they can trust the specifier for consultation on the benefits and disadvantages of a roofing system to determine how to add protection, beauty, and value to a building.
Teaching the benefits and disadvantages of a roofing system
The first responsibility of a specifier is to ensure the owner possesses the information needed to make an informed decision. Some owners may know nothing about roofing and depend on the specifier for insight.
Asphalt shingles are specifically manufactured to comply with ASTM International and/or Underwriters Laboratories (UL) standards for fire resistance (ASTM E108/UL790, Standard Test Methods for Fire Tests of Roof Coverings, Class A, B, or C). Class A fire resistance is the top rating. External-source fires—such as those started by sparks spewed into the air from an adjacent fire—can threaten nearby roofing systems, making a fire resistance system extremely important for protecting a building’s roof. Some roofing products, such as wood, require added chemicals to obtain fire resistance, or have been restricted by building code amendments, or city ordinances from use altogether.
Properly selected asphalt shingles are a highly wind-resistant roofing material when they are installed correctly. Shingles rely on a combination of factory-applied sealant and proper fastening. The sealant helps to hold the shingle tabs in place during wind events. Therefore, it is important to follow the manufacturer’s installation instructions to ensure the sealant performs as intended. Shingles must pass the most stringent wind-resistance examinations, including ASTM D3161, Standard Test Method for Wind-resistance of Steep-slope Roofing Products (Fan-induced Method), and ASTM D7158, Standard Test Method for Wind Resistance of Asphalt Shingles (Uplift Force/Uplift Resistance Method), as recommended by the Federal Emergency Management Agency (FEMA).
For a large portion of North America, shingles with a Class D wind classification are appropriate for use in wind zones up to 145 km/h (90 mph). For coastal regions or other high wind zones, there are shingles with a Class G (for use in zones up to 193 km/h [120 mph]) or Class H (up to 241 km/h [150 mph] zones) certification. When consulting an owner, specifier should confirm the wind zone the projects is located in by consulting local code officials.
Some shingles are designed with impact-resistance properties, often as a protective measure against damage from hailstorms. When consulting an owner in areas where hailstorms are known to be frequent, this performance quality may be of consideration. A common misconception is a thicker shingle provides added impact protection. In reality, this is not necessarily the case. An impact-resistant shingle is reinforced with either a scrim backing or styrene butadiene styrene (SBS)-modified asphalt and has passed the test requirements in UL 2218, Standard for Impact Resistance of Prepared Roof Covering Materials. UL 2218 has four different levels of rating, the most rigorous being Class 4.
Test of time and environment
Its time-tested success is why asphalt shingles cover 80 percent of homes in America and 1 billion m2 (12.5 billion sf) of asphalt shingle products are manufactured annually. Over the past 125 years, shingles have proven they can withstand a wide range of exposure and environmental challenges dispatched by time and nature. From extreme sunlight to the iciest of winters, these materials continue to prove themselves as a sturdy, reliable roofing choice.
Asphalt shingles have a core material made of fiberglass and organic or polyester mat. This gives the product the strength to withstand manufacturing, installation, and service conditions. The mat is coated with asphalt, which serves as the medium for adhering mineral surfacing to the roofing. Some manufacturers blend the asphalt with SBS polymers to add rubber-like characteristics. Asphalt shingles are manufactured as laminated shingles (multilayer), strip, and open tooth. Strip shingles are rectangular and may have multiple cutouts along the long dimension. Cutouts separate the shingle’s tabs, and when exposed to the weather, they give the roof the appearance of being comprised of a larger number of individual units.
When consulting, it is advisable to check with an asphalt shingle manufacturer before making any key decisions. Important questions to consider may include:
One can also visit asphaltroofing.org for a list of North American asphalt roofing manufacturers that are Asphalt Roofing Manufacturers Association (ARMA) members.
Additionally, while shingles are significant, specifiers should stress the importance of the roofing system. A roof is a whole system, and each element deserves attention during the design process.
Specifier as an artist
Asphalt shingles are available with hundreds of aesthetic customization options through different colors, designs, shapes, textures, shades, and styles. While physical requirements (wind resistance, geography, etc.) play an important role in determining shingle selection, a specifier can use knowledge of asphalt shingles’ aesthetic diversity to act as an exterior design consultant and show an owner variety. For example the Burlington Fire Department building in Washington (the 2017 Quality Asphalt Roofing Case-Study [QARC] Bronze winner) mandated two physical requirements: wind and algae resistance. Asphalt shingles not only met these requirements, but also provided a good blend of oakwood.
Regardless of climate or geography, asphalt shingles provide a variety of stylistic choices fit for any installation. If aesthetic decisions are given to an architect for a project, the specifier can recommend shingles with the necessary performance that also fit the architect’s vision. For each design offered, asphalt shingle manufacturers often provide several color scheme options, making it possible to achieve visual perfection without sacrificing a roofing system’s performance values.
One reason shingles offer so much diversity is their granules, which are made from igneous rock covered with a clay silicate mixture in a selected color, coated with a highly durable ceramic, and then surface treated. Besides the aesthetic value these asphalt shingle granules provide, they also assist in ultraviolet (UV) protection, shingle durability, and roofing system longevity.
An owner will likely want to explore many colors and styles before making a final choice. An asphalt shingle roofing system can last a long time, so selecting the right aesthetics for each project may take a little research. Steep-slope roofs represent a significant percentage of the exterior appearance for a building. In the author’s experience, the curb appeal of an asphalt shingle roofing system can have a dramatic impact on resale value.
Shingles come in three basic styles. Traditional three-tab shingles are typically strip shingles with cutouts along the long dimensions. Popular architectural (also known as laminated) shingles are comprised of multiple layers of base material to give a three-dimensional effect. Comprising laminates, luxury/specialty shingles usually give the appearance of a slate or tile roof. They are heavier and may have a greater exposure than typical varities.
Another role a specifier may be asked to fill is an environmentalist. Especially today, many owners would like to make decisions with the environment in mind. Many want to trust their specifiers to make environmentally wise decisions, too. A specifier can build and reinforce this trust by making energy-efficient roofing decisions or recommendations.
Every year, Americans spend $40 billion to air-condition buildings, consuming a sixth of all the electricity generated in the country. An air-conditioner may not seem like a large energy consumer, but when millions of these devices are on at the same time, it becomes much more taxing. By reducing energy consumption, fewer resources are needed to power air-conditioning units, and therefore the strain placed on the environment and energy bills is reduced. For an asphalt shingle roofing system, there are multiple ways of doing this.
A proper attic ventilation system includes a balanced system of intake and exhaust vents for allowing a continuous flow of air through the attic space. As cooler air enters the attic through intake vents, warmer air naturally rises out of the space through an exhaust vent. In combination with correctly installed insulation, this assists with roofing system longevity and energy efficiency by reducing heat buildup. Therefore, less strain is placed on air treatment equipment and energy consumption can be reduced. Note the amount of insulation required will depend on the model energy code in effect for the project’s location.
To ensure sufficient ventilation and reduce energy consumption, 0.09 m2 (1 sf) of net free area (open area for passage of air within a vent) is required for every 14 m2 (150 sf) of vented space, according to the International Building Code (IBC). There are several options for both vent types, such as eave or soffit for intake, and ridge vent or power fan for exhaust.
Asphalt roofing granules not only look pretty, but also can help reduce energy consumption. ‘Cool’ shingles are made with specially treated granules for reflecting solar energy, helping to reduce the amount of heat absorbed by the roofing system. A multitude of ‘cool’ shingles are certified by Energy Star and/or the Cool Roof Rating Council (CRRC) and can help reduce temperatures, thereby reducing the amount of heat transferred to the space and making an air-conditioner’s job easier.
When asphalt shingles’ life cycle finally comes to an end, they can be repurposed for other uses, such as paving new roads. In 2017, nearly 861,826 tonnes (950,000 tons) of reclaimed asphalt shingles (RAS) were used in new asphalt pavement mixes in the United States, according to the National Asphalt Pavement Association (NAPA). Not only does using recycled shingles help stem the use of new natural resources, but it also contributed to more than $2.2 billion in savings last year.
Before making any environmental or energy reduction roofing decisions, one should check with an asphalt roofing manufacturer for recommendations and guidance.
Quality shingle roofs
Today’s construction industry is active and dynamic. By being well-informed on the technology, aesthetics, and energy savings of asphalt shingles, a popular steep-slope roofing option with residential and commercial applications, professionals are better equipped to showcase their knowledge and expertise.
Mike Fischer is vice-president of codes and regulatory compliance for the Asphalt Roofing Manufacturers Association (ARMA). He is a 35-year building industry veteran, leading strategic client initiatives in legislation, regulatory affairs, and standards and construction codes. Fischer is a frequent speaker at industry events and a regular contributor to trade publications. He can be reached at MFischer@kellencompany.com.
Source URL: https://www.constructionspecifier.com/asphalt-shingles-what-owners-want-and-specifiers-need-to-know/
Copyright ©2020 Construction Specifier unless otherwise noted.