How wind attacks a roof
As wind passes over a building, it creates suction that pulls the roofing upward. That force is greatest at the eaves and rakes, at the ridge and at the corners. Once one piece lifts, wind gets underneath and tears off its neighbours.
An opening left as is quickly becomes a roof emergency at the first rain. The layer under the roofing is not made to stay exposed.
On a shingle roof
Each shingle is nailed, then bonded to the row below by an adhesive strip that activates with heat. As long as that seal holds, wind has little grip. With age, the strip dries out and the shingle becomes brittle.
- Torn-off shingles. Pieces are missing, showing a darker surface or the underlayment.
- Shingles lifted and fallen back. They look in place, but the seal is broken and a crease runs across them. They will go in the next gust.
- Damaged ridge cap. The shingles capping the top of the roof are the most exposed.
On a flat roof
Wind grabs a flat roof by its perimeter. The membrane ends at the perimeter, where metal protects it.
- Lifted parapet coping. The sheet metal capping the low wall at the roof edge comes loose, bends or blows away.
- Loose flashing. The metal at the base of walls and around equipment starts flapping.
- Loose membrane. It lifts at the corners or along an edge, sometimes forming a bubble that moves with the wind.
Checking from the ground
Wait until the wind has died down. Then walk around the building, from the yard to the lane.
- Look for pieces of shingle, metal or membrane on the ground and in the neighbours' yards.
- Look at the edges and the top of the roof, with binoculars if you have them.
- Spot anything that is hanging, flapping or no longer straight.
- Inside, look at the top-floor ceiling, or at the attic from the hatch without going in, for daylight or water marks.
- Take dated photos of everything you find.
Notify the insurer
Notify your insurer quickly and keep your photos. Only your insurer can confirm what your policy provides for wind damage. Note the date and time of the gusts. Keep the pieces that fell to the ground, which show what was torn off. Also ask your insurer what it expects from you before you spend money.
Frequently asked questions
A few shingles blew off. Does the whole roof need replacing?
A few missing shingles do not necessarily mean the whole roof needs redoing. On a fairly young roof, the missing shingles are replaced. If the roof is old and the shingles crack when lifted, a repair will hold poorly and we will talk to you about replacement.
Will the new shingles be the same colour?
New shingles are rarely exactly the same colour. The shingles in place have faded in the sun, and colours vary from one batch to another. If you kept shingles from the original installation, bring them out before our visit.
Can wind cause a leak without tearing anything off?
Yes, wind can cause a leak without tearing anything off. Rain driven sideways gets under flashing or backs up under shingles that resist normal rain very well. Note the wind direction. It is a useful clue for our search.