Screws or nails for new drywall under Ontario's Building Code?

Ontario's Building Code sets out fastener spacing for both options. Screws and nails are both permitted; the choice affects spacing requirements, and those requirements differ between walls and ceilings.

Nails vs. Screws: What the Code Sets Out

For nails on ceilings, Ontario's Building Code (clause 9.29.5.8) requires them no more than 180 mm apart along each support, or in pairs spaced about 50 mm apart with each pair no more than 300 mm from the next. On walls, nails go no more than 200 mm apart, or in pairs every 300 mm. Where the board provides bracing, lateral support or fire protection, nails must be no more than 200 mm apart on studs and plates, and the uppermost nails must sit no more than 200 mm below the ceiling line. All nails must be at least 10 mm from the board edge, and the heads must not break through the paper face.

For screws (clause 9.29.5.9), the spacing on ceilings is no more than 300 mm along each support. On walls, screws go no more than 300 mm apart where supports are spaced more than 400 mm apart, and no more than 400 mm apart where supports are 400 mm or less. The same 10 mm edge rule and the no-puncture rule apply to screws as well.

These are minimums for new work, not a design specification. Ask the City's Building Code Services how they apply to your specific renovation before work starts.

A few things the Code does not settle on its own. Clause 9.29.5.3 sets maximum support spacing by board thickness and orientation through a table, but the Code does not name a single board thickness for every situation: ask the contractor which board suits your framing. The Code's fastener rules also apply only to a single layer of gypsum board on wood framing or furring, fixed with nails or screws. Other applications, including steel studs, multiple layers or adhesive, must follow CSA A82.31-M instead.

One cold-weather note from clause 9.29.5.10: if taping and finishing will follow the hanging, the space must be kept at or above 10 °C for 48 hours before taping begins and for at least 48 hours after. That applies whether you use nails or screws.

Ask the contractor which fastener and board they are quoting, and to put the spacing they will follow in writing.