Code Library › Volume 1 › Section 3.1 — General
PART 3 — FIRE PROTECTION, OCCUPANT SAFETY AND ACCESSIBILITYUpdated for the 2024 Ontario Building Code

3.1.6.14.Combustible Interior Finishes

(1) Except as provided in Sentences (2) and (3), combustible interior wall and ceiling finishes referred to in Clause 3.1.13.1.(2)(b) that are not more than 1 mm thick are permitted in a building or part of a building permitted to be of encapsulated mass timber construction. r1 (2) Except as provided in Sentences 3.1.6.4.(3), (4), (7) and (8), combustible interior wall finishes, other than foamed plastics, that are not more than 25 mm thick are permitted in a building or part thereof permitted to be of encapsulated mass timber construction, provided they have a flame-spread rating not more than 150 on any exposed surface or any surface that would be exposed by cutting through the material in any direction. r1 (3) Except as provided in Sentences (4) and 3.1.6.4.(3), (6), (7) and (8), combustible interior ceiling finishes, other than foamed plastics, that are not more than 25 mm thick are permitted in a building or part thereof permitted to be of encapsulated mass timber construction, provided they have a flame-spread rating not more than 25 on any exposed surface, or any surface that would be exposed by cutting through the material in any direction, except that not more than 10% of the ceiling area within each fire compartment is permitted to have a flame-spread rating not more than 150. (See Note A-3.1.11.3.(3)) (4) Combustible interior ceiling finishes made of fire-retardant-treated wood are permitted in a building or part of a building permitted to be of encapsulated mass timber construction, provided they are not more than 25 mm thick or are exposed fire-retardant-treated wood battens.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.