How do you install roof decking?

Before the first sheet

Check the framing. Rafters or trusses that are cracked, rotted or badly crowned need repair first, because the deck will follow whatever is beneath it. Choose panels with a span rating that matches the framing spacing; the rating is stamped on each sheet, and the first number is the maximum roof support spacing in inches. Thicker panels or panel clips are needed when framing is 24 inches apart.

Laying the panels

1. Start at the eave. Snap a line so the first row is straight and square, since every course above follows it.
2. Run panels across the framing. The long dimension goes perpendicular to the rafters.
3. Land ends on framing. Each panel end must sit on the center of a rafter or truss.
4. Stagger the joints. Offset end joints row to row so seams do not line up across the roof.
5. Gap the edges. About 1/8 inch at panel ends and edges lets the wood swell in humid weather without buckling. Georgia humidity makes this one matter.
6. Clip unsupported edges. H-shaped panel clips between rafters keep adjacent edges level where the span rating calls for them.

Nailing

A common residential schedule is 8d nails every 6 inches along panel edges and every 12 inches in the field, with tighter spacing in higher-wind zones and near gable ends. Your local code and the panel maker set the actual requirement, so confirm before you start. Nails that miss the rafter add no holding power and can poke through shingles later.

Do not leave new decking uncovered overnight if rain is possible; wet OSB swells at the edges. Compare panel types in OSB vs plywood roof decking, and see how the deck fits into the system in roof anatomy explained.