This is from Ontario building code
---------------------------------------------------------------------------------------------------------------------------------
9.19.1.2. Vent Requirements
(1) Except as provided in Sentence (2), the unobstructed vent area shall be not less than 1/300 of the insulated ceiling
area.
(2) Where the roof slope is less than 1 in 6 or in roofs that are constructed with roof joists, the unobstructed vent area
shall be not less than 1/150 of the insulated ceiling area.
--------------------------------------------------------------------------------------------------------------------------------
From my observation on houses with metal roof in the city of Toronto, except vents on the roofs for plumbing purpose, it doesn't seem that there are other vents on the roofs as per the requirements of 9.19.1.1. (1) and (2), is there anywhere in the code that vents for metal roof can be exempted from these requirements?
---------------------------------------------------------------------------------------------------------------------------------
9.19.1.2. Vent Requirements
(1) Except as provided in Sentence (2), the unobstructed vent area shall be not less than 1/300 of the insulated ceiling
area.
(2) Where the roof slope is less than 1 in 6 or in roofs that are constructed with roof joists, the unobstructed vent area
shall be not less than 1/150 of the insulated ceiling area.
--------------------------------------------------------------------------------------------------------------------------------
From my observation on houses with metal roof in the city of Toronto, except vents on the roofs for plumbing purpose, it doesn't seem that there are other vents on the roofs as per the requirements of 9.19.1.1. (1) and (2), is there anywhere in the code that vents for metal roof can be exempted from these requirements?