Protection of Cladding from Moisture
(1) A clearance of not less than 200 mm shall be provided between finished ground and cladding that is adversely affected by moisture, such as untreated wood, plywood, OSB, waferboard and hardboard.
(2) A clearance of not less than 50 mm shall be provided between a roof surface and cladding that is adversely affected by moisture, such as untreated wood, plywood, OSB, waferboard and hardboard.
Article 9.27.2.4. Ontario Regulation 332/12 Building Code, Information published by oncodes.ca for educational purposes only.
For clearance of products such as untreated wood, plywood, OSB, waferboard and hardboard should be 8 inches above ground. This clearance, which is called foundation exposure, is there to prevent water from intruding into the structure of your building due to ponding during heavy rains. Even with the best drainage system, rainy seasons in Ontario can overwhelm your home, so it’s best to have the additional protection of adequate ground clearance. If your foundation is more exposed, it will also make insects and other pests easier to detect.
