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

9.21.3.9.Mortar for Chimney Liners

(1) Chimney liners used in chimneys for solid fuel-burning appliances shall be laid in a full bed of (a) high temperature cement mortar conforming to CAN/CGSB-10.3, “Air Setting Refractory Mortar,” or (b) mortar consisting of 1 part Portland cement to 3 parts sand by volume. (2) Chimney liners used in chimneys for oil- or gas-burning appliances shall be laid in a full bed of mortar consisting of 1 part Portland cement to 3 parts sand by volume.
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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.