If your roof shingles keep blowing off repeatedly, it indicates an underlying systemic problem beyond normal wind damage. The most common reason is age-related sealant failure. Asphalt shingles have a thermally activated sealant strip that bonds shingles together for wind resistance. After 15 to 20 years, this adhesive loses strength, granule loss makes shingles lighter, and shingles become brittle, so even moderate winds of 40 to 50 mph can blow them off. Another major cause is improper original installation, including high nailing where nails are placed above the manufacturer nailing line, using too few nails, overdriven nails that cut the mat, or under-driven nails that prevent shingles from sealing flat. Cold weather installation without hand-sealing can leave shingles unsealed for months, making them vulnerable. Poor attic ventilation causes excessive heat that weakens sealant and warps shingles. If your roof is a second layer or overlay, shingles cannot seal properly over the uneven old layer and are more prone to blow-off. Inadequate starter strip at eaves allows wind to get under the first course and peel the roof. If shingles keep blowing off in the same area, there may be a localized issue like inadequate nailing pattern or wind funneling due to roof shape. Widespread recurring blow-off usually means the roof is at end of life and needs full replacement with proper installation techniques and 6 nails per shingle in high wind areas.
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