Figure 1: Oriented Strand Board

OSB Frequently Asked Questions

Q How do I install OSB as roof sheathing?

A Select the correct thickness or span rating for the application as per local building code requirements. Make sure the rafters or upper truss chords are in alignment, even and straight. (Curved or uneven rafters and upper chords affect the finished roof appearance.)

Panels should be installed textured side up with their long direction across the rafters or truss chords. Long panel edges should be supported or joined with edge clips where specified by the drawings or installation instructions. Leave a 1/8" (3 mm) gap at panel edges or ends to allow for movement due to changes in humidity.

Panels should be staggered at least two supports, and end joints must lie over supports. Use 2 1/2" (63 mm) common (8d) or 2" (50 mm) deformed shank or ring thread nails at 6" (150 mm) o.c. on panel edges, at 12" (300 mm) o.c. along intermediate supports and 3/8" (10 mm) minimum from panel edge. Staples may be used instead of nails - please consult your local building code for size and spacing. Stand over the trusses or rafters when nailing.

The roof should be dry prior to shingling and should be shingled as soon as possible after installation of sheathing. It is essential that the area under a roof system is adequately vented with 50 percent of the venting at the ridge and 50 percent around the eaves. Vent roof as specified in the appropriate building code or as shown on the approved drawings.

< Previous FAQ | Next FAQ >