The Ontario Building Code | Slope of Smoke Chamber
9.22.7.1. Slope of Smoke Chamber
(1) The sides of the smoke chamber connecting a fireplace throat with a flue shall not be sloped at an angle greater than 45° to the vertical.
In Plain Language
The smoke chamber, the transitional area between the firebox and the flue, must be sloped as set out in this article, ensuring smoke flows smoothly upward without turbulence or spillage.
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.