Why Are the Edges of My Roofing Plywood Warping?

Overheating

• The attic or crawlspace below the roof can be a very warm place. As we all know, heat rises. If the heat doesn't have a way to get out of this space, the temperature will continue to rise. This makes the surface directly underneath the roof very hot, which in turn can lead to warping of the plywood edges. If you notice warping, inspect your vents and, if necessary, install a new one to move the heat properly out of the area.

Water Damage

• Water damage is a common cause of warped plywood. Wood building materials typically are transported to a job site and then left out until the roof or even the entire house is assembled. Even if this wood is covered with tarps, it still is subject to moisture and temperature changes, which can lead to warping. Worse, the damage may not be apparent while the job is being done, and the warping will not appear until the wood begins to dry out. If you just had your roof constructed and notice this warping, this probably is the cause.

Badly Sealed Wood

• If you live in a very wet climate and the plywood roof edges are exposed, they will need to be sealed. Otherwise, the wood is going to continue to get wet and the warping will get worse. Use a clear wood sealant and cover the wood to prevent any future damage. If the plywood is very warped, the only solution will be to replace it and then seal the wood that is used in its place.

Type of Plywood

• Plywood is a universal term, but it actually comes in many different grades. Oriented strand board is a type of plywood used in building projects. However, it is not weather resistant and is not a good choice for a roofing material. The small strands of wood will swell and shrink, and warping is common. Make sure your roofers use only construction grade plywood to avoid this problem.