Shingle product development has generally been slow compared to technology evolution in other industries. The most important performance requirements of asphalt shingles, like shedding water, fire and wind resistance, durability and code compliance, have been established for decades. Within the past 35 years, though, there has been a push to develop additional performance standards for asphalt shingles.
The current (and long-standing) product standard for fiberglass asphalt shingles is ASTM D3462. This standard focuses on the physical performance measures of shingles at the time of manufacturing. A number of areas tested include the “recipe” of the shingle (glass mat, adhesive, finished weight, etc.) and performance requirements, such as tear strength, behavior on heating, fastener pull-through resistance (the force needed to pull a nail through the shingle at high and low temperatures), and penetration and softening point of the asphalt.
However, some manufacturers have fought to raise the performance requirements that shingles must meet. Rather than focusing on performance at the time of manufacture, these manufacturers want to establish a standard that would reflect how shingles perform over time. In 2011, the ICC Evaluation Service, Brea, Calif., approved a new alternative acceptance criterion for asphalt shingles, AC438. Instead of dictating how to make an asphalt shingle (what raw materials to use), it requires additional physical property and performance testing beyond ASTM D3462.
AC438 contains stringent performance testing requirements, which are meant to evaluate the performance of a shingle over time. “When thinking about shingle performance, it’s imperative we, as an industry, are looking not just at performance at the time of manufacture. AC438 helps test in these extreme environments to give us better insight,” says Emily Videtto, vice president of shingles and new product development at GAF, Parsippany, N.J. The shingles are put through three critical, demanding tests to evaluate durability in a variety of temperatures and weather situations:
- Temperature cycling. This looks at long-term extreme-temperature resistance—how shingles can withstand winter cold or summer heat. The tests occur in 12- to 24-hour cycles, so it takes 12 days to put the shingle through extreme high and extreme low temperatures. The low temperature is done after soaking in water. Under five times magnification, the shingles are inspected for signs of tearing or cracking that show the glass mat, butt joints in the first course and no separations greater than 1/4 inch, and no evidence of tearing around fasteners or pull through. If any of these conditions exist, the material fails the test.
- Weather resistance. This test looks at how shingles perform after long-term exposure to the sun. Using ASTM G155, a Xenon Arc weatherometer that tests for accelerated weathering, shingles are subjected to 2,000 hours of light and water in cycles for 83 days. After that’s complete, there is a visual examination for evidence of surfacing loss, erosion or exposed reinforcement. Shingle samples must have a minimum of 80 percent of their original breaking strength to pass this stringent test.
- Wind-driven rain. This determines how shingles stand up to heavy, driving rain. The shingles are tested under Florida Building Code Test Protocol TAS-100 with the minimum slope specified by the manufacturer. No water should infiltrate through the sheathing and there should be no blow-off, tear-off or release of the shingle (or any portion of it). The test subjects the shingles to 15 minutes of wind and water, then 10 minutes off, then back on again with wind speeds going to 35, 70, 90 and 110 mph. This results in 8 inches per hour of rain to test the shingle’s performance. A camera is mounted on the underside to look for any water intrusion during the test.
AC438 also looks at the weight of the displaced surfacing over the asphalt coating. With ASTM D3462, the requirement is one gram of granule loss. AC438 requires less displaced surfacing, so more granules need to be kept on the surface of the shingle to better protect it.
These additional tests challenge shingle manufacturers to make a better-quality product to meet the requirements found in AC438. GAF was the first shingle manufacturer to provide independent verification to the requirements of AC438 and additional manufacturers have since followed. These tests are a big step forward in evaluating performance and choosing a shingle that has the qualities to stand the test of weather and time. This type of testing ultimately helps roofing contractors because they want to know that the shingles they are installing will pass these stringent tests and provide stronger protection against the elements. For homeowners, they can feel comfortable they are installing a top-performing shingle that will help protect their most valuable asset.
Today, all GAF shingles comply with ASTM D3462 and AC438, as well as pass the industry’s two toughest wind-resistance tests: ASTM D3161, Class F (110 mph), and ASTM D7158, Class H (150 mph). These code advancements and stronger tests have helped to change the manufacturing of roofing shingles from an art to a science. This science comes through years of research, lab testing, and development to find the right mix of materials and production processes to produce a technologically advanced shingle. In fact, GAF created its own shingle science with Advanced Protection Shingle Technology, aimed at pushing the envelope to deliver shingles with the most advanced design, manufacturing, and testing techniques for quality and longevity in an asphalt shingle.