What is the term for raised areas or bubbles that may appear on the surface of asphalt roofing after installation?

• A. Blisters
• B. Blow-off
• C. Buckling
• D. Butt edge

Answer: (A)

Raised pockets on asphalt roofing are called blisters. They form when air or moisture becomes trapped beneath the surface and heat causes that pocket to expand, pushing the surface upward into a bubble. This can happen if the roof deck is damp, if shingles are installed over a moist substrate, or if heat buildup during installation or sun exposure drives moisture out from under the shingle. Blisters compromise the roof’s waterproofing and can lead to leaks if left untreated, so the typical approach is to address the moisture source, allow the deck to dry, and replace the blistered area as needed. They should not be confused with other issues like blow-off (shingles pulled off by wind), buckling (warping of shingles), or the butt-edge (the lower edge where shingles meet).