The Ontario Building Code | Height of Chimney Flues
9.21.4.4. Height of Chimney Flues
(1) Achimney flue shall extend not less than,
(a) 900 mm above the highest point at which the chimney comes in contact with the roof, and
(b) 600 mm above the highest roof surface or structure within 3 m of the chimney.
In Plain Language
A chimney's height must meet the requirements set out in this article, ensuring proper draft and safe dispersal of combustion byproducts above the roofline.
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.