What is the Cause of Cracks in Fiberglass-based Asphalt Roof Shingles?
• It’s possible that shingles made by some manufacturers do not meet the ASTM Standards for tear resistance. • Even where shingles meet the Standards, it’s possible that the standards themselves were defective. In particular, for a time the asphalt roof shingle standards combined these concerns: A thin fiberglass mat was permitted as the shingle substrate, lacking adequate tear resistance • The wind uplift prevention bonding adhesive was too strong, causing the shingles to bond into nearly a single continuous surface that lacked adequate movement to respond to significant changes in temperature without tearing the bound surface • In any case, Fiberglass mat may lack adequate tear resistance • Self-sealing tabs on shingle backs may glue shingles together with too much strength, causing the roof covering to form a single large membrane which cannot accommodate large temperature changes. This explanation was discovered across the asphalt shingle industry. • Reduced total amount of asphalt
