I am trying to understand the fire code here: http://www.cufca.ca/fire.php.
I want to put up some hardboard to cover ridig foam in my basement walls. What does the code mean by “3 mm thickness over continuous back-up?”
9.29.7. Hardboard Finish
220.127.116.11. Material Standard
1) Hardboard shall conform to CAN/CGSB11.3-M, Hardboard.
1) Hardboard shall be not less than
a) 3 mm thick when applied over continuous back-up,
b) 6 mm thick when applied over supports spaced not more than 400 mm o.c., and
c) 9 mm thick when applied over supports spaced not more than 600 mm o.c.
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