(1)  If fire-retardant treated wood is specified in this Part, the wood shall,

    (a)   be pressure impregnated with fire-retardant chemicals in conformance with CAN/CSA-O80 Series, “Wood Preservation”, and

    (b)   have a flame-spread rating not more than 25.

Article 3.1.4.5 Ontario Regulation 332/12 Building Code,   Information published by oncodes.ca for educational purposes only.