IBHS wind testing of asphalt shingle products has demonstrated that the most important factor affecting high-wind performance for self-sealing asphalt shingles is the strength of the seal between shingles. Self-sealing asphalt shingles contain a temperature-activated adhesive strip applied during the manufacturing process, which is used to adhere the lower-edge bottom surface of the exposed top shingle to the top surface of the shingle below.
Improvements in sealants has resulted in dramatic increases in the wind ratings of self-sealed asphalt shingles. Nevertheless, asphalt shingle manufacturers typically indicate that hand-sealing of these shingles is required when shingles are installed on steep-slope surfaces or during extended periods of cold weather. The Asphalt Shingle Manufacturers Association (ARMA) recommends hand-sealing for slopes greater than 12:12 (45 degrees) or when shingles are installed during very cold weather. Despite these recommendations, hand-sealing of self-sealing asphalt shingles is not common practice for winter or steep-slope installations.
IBHS conducted an exploratory research program during 2015 and 2016 to determine whether wind uplift resistance for newer products could be significantly affected by installation when temperatures were very cold or by slope for more common roof slopes (between 2:12 and 12:12).