When installing a home, which layer is applied first before siding is attached?

The correct answer is the sheathing, which is the layer that is applied first before siding is attached. Sheathing typically comprises sheets of plywood or oriented strand board (OSB) nailed to the exterior framing of a house. Its primary function is to provide structural stability, offering support and forming a solid surface for attaching the siding.

This layer also serves as a barrier to moisture and air infiltration, enhancing the overall energy efficiency of the building. Once sheathing is in place, the next steps would involve placing a moisture barrier or house wrap over it to further protect against weather elements before the final siding material is installed.

Insulation is important, but it is usually placed within the wall cavities or sometimes on the exterior, following sheathing. Drywall is an interior material and is applied after the framing is completed and not relevant to the installation process of the exterior siding. Roofing material is installed on the roof and has no bearing on siding application, as it addresses a different aspect of the building envelope.