Wind Effects on Asphalt Shingles

This paper will explore various failure modes of asphalt shingle roofs in windstorms. Roofs in three subdivisions were analyzed after Hurricane Frances struck Florida in 2004. Wind damage involved unbonding, creasing, flipping, and displacing shingles from the windward slopes where three second wind gusts ranged from 33 to 43 m/s at 10 m. Laminated type shingles significantly outperformed tab type shingles.

We also will discuss why many shingle roofs have little to no bond. Age, installation, and expansion-contraction effects have resulted in straight-up or diagonal patterns where shingles were not bonded on each directional slope. Such uniform bonding problems have been observed in non-hurricane regions. Thus, it is important for roof inspectors to understand the nature of shingle bonding in order to properly assess wind damage to roof coverings.

Finally, the results of field uplift tests will be presented where bond strength was measured on selected roofs. Once the bond was broken, the tabs were resealed with adhesive then retested to determine the bond strength of the repairs. It was found that resealed shingles had higher bond strengths.