(1) OSB conforming to O-2 grade shall be not less than 6.0 mm thick where applied directly to sheathing.
(2) OSB conforming to O-2 grade applied directly to framing or over furring strips shall conform to the thickness shown for plywood in Table 9.27.8.2.
(3) OSB conforming to O-1 grade and waferboard conforming to R-1 grade shall be not less than 7.9 mm thick where applied directly to sheathing.
(4) Where applied directly to framing or over furring strips, OSB conforming to O-1 grade and waferboard conforming to R-1 grade shall be not less than,
(a) 9.5 mm thick on supports spaced not more than 406 mm o.c., and
(b) 12.7 mm thick on supports spaced not more than 610 mm o.c.