What is roof sheathing?

Roof sheathing refers to the layer of wood attached to your roof joists that provides a strong, structural layer onto which shingles are attached. There are different types of sheathing used in our area. Which type of sheathing your home has depends on a few factors such as the age of your home and the type of roofing material your home has installed. We’ll go over the most commonly found sheathing types, some issues you may find with these, and what to expect in terms of price or scope of work below.

OSB (Oriented Strand Board) is the most common roof sheathing in CA. Most homes built after the mid 1980s have OSB sheathing. It’s fairly waterproof due to the resins and glues used in production, relatively cheap and easy to install. 7/16” OSB is our go-to material for dry rot repairs or sheathing updates.

Plywood is also common in homes built in the 80’s or 90’s. It’s heavier, a little more costly, less water resistant, but slightly stronger than OSB. If your home has plywood sheathing, we’ll replace any rotten areas with plywood rather than OSB.

You may find solid wood sheathing on older homes. Sometimes it’s installed without gaps, sometimes we find what is commonly called ‘skip sheathing’ with larger gaps between the 1”x6” boards. Solid sheathing with only small (1/4” to 1/2” inch) won’t need replacing as long as it’s structurally sound. Skip sheathing will require a new layer of OSB or plywood to comply with current building code.

Be sure to ask your contractor what their plans are for reusing, repairing, or replacing your home’s existing sheathing. This can be the largest opportunity for change orders down the road and you may not find out your home needs all new sheathing until the roof is torn off, which can add thousands to the total cost of your roof.

If you have any questions regarding the type of sheathing your home has, please reach out for a free consultation and estimate today!