The Ontario Building Code | Fire Chamber Dimensions
9.22.4.1. Fire Chamber Dimensions
(1) The distance from the back of the fire chamber to the plane of the fireplace opening shall be not less than 300 mm.
9.22.5. Hearth
In Plain Language
The fire chamber (firebox) must meet the dimensional requirements set out in this article, sized appropriately for safe, effective operation.
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.