The Ontario Building Code | Fresh Air Inlets
7.5.5.4. Fresh Air Inlets
(1) Where a building trapis installed, a fresh air inlet not less than 4 in. in size shall be connected upstream and within 1 200 mm of the building trapand downstream of any other connection.
In Plain Language
Where a building trap is installed, a fresh air inlet of at least 4 in. size must connect upstream and within 1200 mm of the building trap, letting outside air into the system to maintain proper airflow.
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.