Wind damage is one of the conditions that may ultimately lead to roofing failure. Understanding how wind causes damage can help you anticipate potential problems before they can become bigger headaches.
Wind uplift is a phenomenon where a vacuum is formed as the wind hits a vertical wall. This creates suction on the roof surface, which results in an upward force. This results in a pocket of vacuum, which, if strong enough, can overcome shingles or sheet metal, and tear them off the roofing surface.
A change in wind speed can also create uplift because of the sudden change in wind direction, which results in lower air pressure. Both suction and spots with low pressure can occur during a storm, leading to torn-off asphalt shingles.
Positive pressure is somewhat similar to uplift in that the damage is caused by wind hitting something that offers resistance: a wall, fascia board or a roof with a steep slope. Old, loose or improperly nailed asphalt shingles get torn off; those that stay on the roof will have horizontal cracks about an inch below the edge of the shingle. These asphalt shingles are, quite literally, folded by the wind.
This is why many roofing products have adhesive strips. Positive pressure can also damage other exterior components like gutters and siding, often to the point that a siding replacement may be necessary.
One common example of indirect wind damage is when debris, gravel and other small objects left in the yard are lifted and thrown onto the house, effectively turning them into missiles. Roofing materials like slate and tile as well as vinyl siding and windows are vulnerable to such hits. The faster the wind, the greater the damage can be. While the aforementioned types of wind damage can be minimized with proper roof design and regular care and maintenance, keeping the yard clean can help reduce the number of potential projectiles.