Required Insulation

(1)  All walls, ceilings and floors separating heated space from unheated space, the exterior air or the exterior soil shall be provided with thermal insulation in conformance with Section 12.2. to prevent moisture condensation on their room side during the winter and to ensure comfortable conditions for the occupants.

Article 9.25.2.1 Ontario Regulation 332/12 Building Code,   Information published by oncodes.ca for educational purposes only.