What is Sheathing?

Definition of Sheathing in Construction

The covering of a structural system on the wall, roof, ceiling, etc. The skin of the structure is created with the use of sheathing, which can be made-up of a variety of materials. Sheathing is normally plywood, plyscore, fiberglass panels, insulation board, etc. The use of sheathing is basically to provide a substrate for the finish siding material which could be masonry, vinyl, or any other finish material that is installed over the sheathing. Prior to the manufacturing of plyscore or plywood as a sheathing material, separate wooden boards were used to provide a substrate for a roofing or siding material. To sheath a project is to install the roof substrate or the wall substrate.

Sheathing is an important element to the entire wall or roof system. The placement of a vapor barrier is important to protect the sheathing from damage due to rot. A vapor barrier is a waterproof material that eliminates the transfer of moisture from one surface to the next. The sheathing, whatever it is, must be kept dry by ensuring that there is a flow of air between the sheathing and the siding. Without this flow of air and a properly located vapor barrier, the finish siding could fail. If the siding is to be painted or stained, the elimination of a moisture build up is important for the durability of the paint. Shingles