What thickness of drywall is required and how must it be fastened in Ontario?
Gypsum board thickness depends on framing spacing: 12.7 mm (1/2 in) board suits supports at 600 mm (24 in) on centre, while 9.5 mm (3/8 in) is limited to 400 mm (16 in) spacing. Nails or screws follow prescribed spacing and edge distances.
Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.
The thickness table is the practical takeaway: standard 12.7 mm board covers virtually all residential framing layouts, while 9.5 mm is only legal on tight framing and sags on ceilings, especially under insulation, so most builders use 12.7 mm or sag-resistant ceiling board everywhere. Screws hold better than nails and avoid nail-pops. Remember that fire-rated locations, like garage-to-house separations or between dwelling units, may require specific board types and thicknesses under Section 9.10, which overrides these general finish rules.
Half-inch drywall is the safe standard for walls and ceilings in Ontario homes. Thinner board is only allowed when studs or joists are close together, and screws must go in at set spacings so the sheets never sag or pop.
Get answers like this for any code question
BUILDAiD Assist searches the building code and answers in plain English with exact citations — in seconds.
This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.