How does wind cause damage?

When wind passes over and around a building, it generates inward or outward pressures on the walls and inward or outward (uplift) pressures on the roofs. Inward (positive) pressures are generated on the windward side of the building as the wind blows against a wall or roof surface, such as a steep roof. This positive pressure does not damage shingles unless the tabs are lifted such that the pressure can get under the tab. Outward (negative/suction/uplift) pressures are generated when the wind passes by a wall, passes away from a wall (leeward side of the building, that is, the side not facing the wind), passes over a shallow sloped roof, or passes over the leeward slope of the roof. It is this negative or suction pressure that lifts a tab or a shingle strip. The magnitude of the positive or negative/suction pressures on the shingles of a building is determined not only by the speed of the wind, but also by the orientation of the roof slope to the direction of the wind and the location of the shingles on the roof slope.

Wind Diagram

What do shingle manufacturers’ say about wind?

Shingle manufacturers’ make numerous types of shingles. The wind resistance of shingles is broken into three classes, Class A, Class D, and Class F. These are defined in ASTM D3161-09 (the standard test method for wind-resistance of asphalt shingles). Class A shingles pass a test wind velocity of 60 mph, Class D shingles 90 mph, Class F 110 mph.

The manufacturers’ warrantees for wind resistance vary from 60 mph for the 20 to 25 year warranty shingles to 130 mph for the lifetime warrantee shingle


How do I know if my roof has wind damage?

Wind doesn’t have to be that strong to cause roof damage to your home. Gusts of wind at 75 to 85 miles per hour can easily raise shingles off your home in a second, exposing your roof to possible rain & water damage. Not all damage is visible (like the following pictures show) but all damage will result in leaks and further damage if left un-repaired.

What do I do if my roof has wind damage?

If your roof has wind damage, or you even suspect it, contact us TODAY!