Sheathing
CSI Division 06, Wood, Plastics & Composites
Structural panels, plywood or oriented strand board (OSB) most commonly, fastened to the outside of a building's wall or roof framing to tie the frame together, provide a nailing surface for the exterior finish, and, on walls, often serve as the structure's lateral bracing against wind and seismic loads.
Why it matters
Sheathing's nailing pattern, fastener spacing and edge distance, is engineered for the specific lateral loads the wall or roof has to resist, not just to hold the panel in place, so a crew that skips fasteners or over-spaces them can leave the structure without the shear capacity it was actually designed for.
On a real project
A framing crew installs OSB wall sheathing following the nailing schedule called out on the structural drawings, with tighter fastener spacing at panel edges specifically required for the wall's designated shear resistance.
Who this matters most to
A Carpenter installs sheathing following the specified nailing pattern. A Structural Engineer specifies that pattern based on the lateral loads the wall or roof has to resist.
Where this goes wrong
A framing crew installs wall sheathing quickly using a wider fastener spacing than the structural drawings specify, assuming any reasonable nailing pattern is close enough. A later inspection catches the shortfall, and the crew has to add fasteners throughout the wall to bring it up to the specified shear capacity.