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

9.21.3.8.Spaces Between Liners and Surrounding Masonry

(1) A space not less than 10 mm wide shall be left between a chimney liner and the surrounding masonry. (2) The space required in Sentence (1) shall not be filled with mortar.
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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.