The Ontario Building Code | Steel Liners
9.22.2.3. Steel Liners
(1) Steel liners for fireplaces shall conform to CAN/ULC-S639M, "Steel Liner Assemblies for Solid-Fuel Burning Masonry Fireplaces", and shall be installed in accordance with the installation instructions in that standard.
9.22.3. fireplace Walls
In Plain Language
Steel liners for a fireplace have their own specific requirements set out in this article, an alternative to firebrick lining.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.