The Ontario Building Code | Required Damper and Size
9.22.6.1. Required Damper and Size
(1) The throat of every fireplace shall be equipped with a metal damper sufficiently large to cover the full area of the throat opening.
9.22.7. Smoke Chamber
In Plain Language
A damper is required, sized as set out in this article, letting the fireplace opening be closed off between uses to prevent heat loss and control draft.
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.