Shingles not laying flat can be caused by a variety of installation, age, and environmental factors. For new roofs, the most common reason is that shingles were installed in cold weather below 40 degrees Fahrenheit when the factory-applied sealant strip did not have enough heat to activate and bond. These shingles may appear lifted until warm weather seals them, but they should be hand-sealed if they do not seal within a few weeks. Another new roof cause is improper nailing, such as nails placed too high, overdriven nails breaking the mat, or too few nails, which prevents shingles from sitting flat. Wavy or uneven decking, such as plywood that was not properly spaced and has swollen, will cause shingles to telegraph the unevenness and not lay flat. For older roofs, shingles not laying flat usually indicates aging and moisture issues. Cupping and clawing occur when shingles lose their volatile oils and shrink unevenly due to UV exposure and heat. Poor attic ventilation causes heat buildup that cooks shingles from below, leading to warping and curling. Moisture trapped in the mat from ice dams or leaks can cause swelling and buckling. If shingles were installed over an existing layer during a layover, they will not lay flat over the uneven old shingles. Widespread failure to lay flat signals the roof needs replacement.
1 votes
Marked as accepted