(1)  Every attic 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 house or an individual dwelling unit in a house, the hatch may be reduced to,

    (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.

Article Ontario Regulation 332/12 Building Code,   Information published by oncodes.ca for educational purposes only.

Note : Except for very small attic spaces, attics require an access hatch. The area of the hatch must be at least 0.32 m2 (3.4 sq. ft.) with no dimension less than 500 mm (20 in.).