2024 Ontario Building Code Guide: Dampproofing and Moisture Protection Standards
Sarah's Expert Insight
OBC Compliance Specialist
"In regions like London and Oakville, where soil moisture levels fluctuate significantly, strict adherence to Section 9.13.2.5 is the only way to prevent subterranean rot in finished basements. At empcontracting.ca Inc. your construction contractor in London, Ontario, we recommend high-performance bituminous membranes for Muskoka builds to handle the unique hydrostatic pressures of the northern landscape, ensuring a bone-dry interior regardless of the season."
Compliance with OBC Section 9.13.2 for Ontario Construction
Proper moisture management is the foundation of a healthy home. According to the 2024 Building Code Compendium, specific material standards and preparation protocols must be met to ensure foundation longevity. At empcontracting.ca Inc. your construction contractor in London, Ontario, we strictly adhere to these standards to prevent water ingress and structural damage.
Material Standards and Vapour Permeance
To meet code, dampproofing materials must exhibit a water vapour permeance of no more than 43 ng/(Pa·s·m²) when tested under ASTM E96 standards. Approved materials include:
- Vapour-resistant coatings
- Cold-fluid-applied or hot-rubberized bituminous membranes
- Liquid-applied or spray-applied asphalt-based emulsions
- Type III hot-applied asphalt
9.13.2.3. Surface Preparation Requirements
Success starts with preparation. The OBC mandates that the application area remain water-free during the process. Key preparation steps include:
- Manufacturer Compliance: Following specific instructions for both dampproofing and Insulating Concrete Form (ICF) materials.
- Masonry Parging: Unit masonry walls must be parged on the exterior face (minimum 6 mm mortar) and coved over the footing.
- Surface Condition: Concrete walls must have all holes, recesses, and cracks sealed. Surfaces must be clean, dry, and free of debris, ice, or oil that could compromise the membrane.
9.13.2.4. Application of Dampproofing
Exterior dampproofing must extend from the finished ground level to the top of the exterior footing. It is essential to maintain continuity across joints, cracks, and penetrations to prevent localized failures in the moisture barrier.
9.13.2.5. Protecting Interior Finishes
When finishing a basement, the interior surface of foundation walls below ground level requires protection. This is mandatory where separate interior finishes or wood members are in contact with concrete or masonry. The protection must extend from the basement floor to the height of the insulation, ensuring a moisture-tight seal that protects the interior living space.
Disclaimer: This content is generated from the Ontario Building Code for educational purposes. Always consult with a licensed professional engineer or your local building department before starting any construction project in London, Ontario.