(1)
Hardboard cladding shall be not less than
(a)
9.5 mm thick when applied over sheathing that provides continuous support or over furring or framing members not more than 400 mm o.c., or
(b)
11.1 mm thick when applied over furring or framing members not more than 600 mm o.c.
(2)
Where hardboard cladding is grooved, the grooves shall not extend more than1.5 mm into the minimum required thickness. (See Note A-9.27.9.2.(2))