Gypsum Board Supporting Insulation

(1)  Gypsum board supporting insulation shall be at least 12.7 mm thick.

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


Although 9.5 mm (3⁄8 in.) thick gypsum board may be used on walls with support spacings up to 400 mm (16 in.) on centre when the boards are oriented perpendicular to the framing, 12.7 mm (1⁄2 in.) gypsum board is more commonly used because of its extra stiffness and strength. Where supports are spaced at 600 mm (24 in.) on centre, the minimum thickness should be 12.7 mm (1⁄2 in.). When gypsum board supports insulation, it must be at least 12.7 mm (1⁄2 in.) thick. Some ceiling gypsum board is specially designed to resist sagging when water-based textured finishes are applied to a ceiling. A 12.7 mm (1⁄2 in.) panel can be installed perpendicular to supports at spacings up to 600 mm (24 in.).

Source : Canada Mortgage and Housing Corporation (CMHC)

Drywall, also known as gypsum board or plasterboard, is a solid material made of gypsum (calcium sulfate dihydrate). Gypsum has several interesting properties: it’s light and tough, yet it’s also very strong. Drywall is one of the most commonly used building materials in Canada today. Drywall is used to create walls and ceilings.