Half-inch or five-eighths drywall for walls in a Kanata renovation?

Ontario's Building Code does not name one board thickness for every wall. It sets a minimum of 1/2-inch (12.7 mm) for board that supports insulation (O. Reg. 163/24, 9.29.5.4.(1)), and its Table 9.29.5.3 sets the maximum spacing of supports by board thickness, orientation and whether the surface is painted or textured. These are Building Code minimums for new work; ask the City how they apply to your renovation, and ask the contractor which thickness suits the framing in your rooms.

Where 5/8-inch (15.9 mm) Type X drywall comes in is a secondary suite. For new work the Code gives two routes for separating the units: a fire separation with a 45 minute rating (9.10.9.16.(1)), or a continuous smoke-tight barrier of not less than 5/8-inch Type X on both sides of the separating walls and on the underside of the floor-ceiling framing (9.10.9.16.(4)). The City decides which route applies through the permit. Between a single home's attached garage and the house, the Code requires a sealed gas barrier, not Type X.

What a complete quote for the walls should state:

• the board thickness and type, wall by wall
• the finish level by number
• the number of coats, sanding and primer, in or out
• how off-cuts and debris are handled

The Gypsum Association's GA-214 guide, an industry recommendation rather than a Code requirement, lists Level 4 for flat paint and Level 5, a thin skim coat over the whole surface, for gloss or dark paint.

Published Toronto and Ontario contractor prices for hanging, taping and finishing new board run about $1.50 to $4.50 per square foot of board, read October 1, 2026; these are not Ottawa prices. If the house was built before 1990 and old board is coming out, ask who arranges the asbestos test before any cutting or sanding begins.

Have the board thickness for each room written into the quote, so the price you compare is for the same board.