The Ontario Building Code | Access
(1) Everyattic or roof space shall be provided with an access hatch where the attic or roof space,
(a) measures not less than,
(i) 10 m² in area,
(ii) 1 000 mm in length or width, and
(iii) 600 mm in height over at least the area described in Subclauses (i) and (ii), or
(b) contains a fuel-fired appliance.
(2) Except where an attic or roof space contains a fuel-fired appliance, the hatch required in Sentence (1) shall be not less than 550 mm by 900 mm except that, where the hatch serves a single dwelling unit, the hatch may be reduced to,
Note: On July 1, 2017, Sentence 126.96.36.199.(9) of Division B of the Regulation is amended by striking out "single dwelling unit" in the portion before Clause (a) and substituting "house or an individual dwelling unit in a house". (See: O. Reg. 139/17, s. 122)
(a) 0.32 m2 in area with no dimension less than 545 mm, or
(b) 500 mm by 700 mm.
(3) Hatchways to attic or roof spaces shall be fitted with doors or covers.
Section 9.20. masonry and insulating Concrete Form walls Not in Contact with the Ground