The Ontario Building Code | Roof Access
3.2.5.3. Roof Access
(1) On a building more than 3 storeys in building heightwhere the slope of the roof is less than 1 in 4, all main roof areas shall be provided with direct access from the floor areasimmediately below, either by,
(a) a stairway, or
(b) a hatch not less than 550 mm by 900 mm with a fixed ladder.
(2) Clearance and access around roof signs or other obstructions shall provide,
(a) a passage not less than 900 mm wide by 1 800 mm high, clear of all obstructions except for necessary horizontal supports not more than 600 mm above the roof surface,
(i) around every roof sign, and
(ii) through every roof sign at locations not more than 15 m apart, and
(b) a clearance of not less than 1 200 mm between any portion of a roof sign and any opening in the exterior wall face or roof of the building in which it is erected.
In Plain Language
This clause requires an access route suitable for fire department vehicles to reach the building, wide and strong enough to support heavy apparatus, so trucks and equipment can actually get close enough to fight a fire.
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.