Roof Sheathing Rot

For starters you may notice a leak in your ceilings that originated from your roof.

Roof sheathing rot.

All roofs have a layer of plywood sheathing underneath them which provides a base for the shingle attachment. Although the plywood typically lasts longer than most shingles and roof coverings leaks can cause them to rot. Damaged shingles and rotted plywood must be removed before replacing them with new plywood and roofing material. These thin sheets of wood absorb moisture when exposed to it through excess condensation or a roof leak.

Rotted plywood is identifiable by sinking areas of the roof or visible leaks. Some signs that roof sheathing is damaged or rotted include a sagging ceiling noticeable roof leaks and missing patches of roof shingles or tiles. Wood sheathing will eventually rot as excess moisture continually collects on it and the material is unable to properly dry out. When sheathing is exposed to moisture frequently there is always a chance it will decay or develop wood rot.

Nonetheless there are still telltale signs that indicate you have a sheeting issue. When replacing roof decking you first need to get rid of the old rotten section. Most roof decking also called sheathing is plywood or oriented strand board osb. You may need to cut a little extra to expose enough of the trusses and make sure you get rid of all the rotten wood.

As mentioned it is near impossible to see roof sheathing making it very hard to determine when it starts to rot. Set the depth of your circular saw to the thickness of the roof decking.