The Ontario Building Code | Roof Access
220.127.116.11. 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.