Code Library › Volume 1 › Section 9.21 — Masonry and Concrete Chimneys
PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code

9.21.4.9.Separation of Flue Liners

(1) Flue liners in the same chimney shall be separated by not less than 70 mm of masonry or concrete exclusive of liners where clay liners are used, or 90 mm of firebrick where firebrick liners are used. (2) Flue liners referred to in Sentence (1) shall be installed to prevent significant lateral movement.
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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.