2024 Ontario Building Code Guide: Stucco and Waterproof Wall Finish Standards
Sarah's Expert Insight
OBC Compliance Specialist
"Precision in stucco layering and shower waterproofing heights is vital for protecting homes against Ontario's seasonal humidity shifts, especially in regions like London, Oakville, and Muskoka. At empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure every millimetre of thickness meets the 2024 Compendium standards to prevent sub-surface rot and mold growth in our clients' projects."
Understanding OBC Requirements for Stucco Application (Section 9.28.6)
Proper stucco application is essential for maintaining a durable and weather-resistant building envelope. According to the 2024 Ontario Building Code, a standard three-coat process must follow specific thickness and adhesion protocols.
The Three-Coat Stucco Process
- First Coat: Must be at least 6 mm thick, fully embedding the lath. The surface must be scored to ensure a mechanical bond with the subsequent layer.
- Second Coat: Must be at least 6 mm thick. Unless a stone dash finish is applied, this surface should be lightly roughened to facilitate the finish coat's adhesion.
- Finish Coat: Requires a minimum thickness of 3 mm. For non-stone dash finishes, the base must be dampened (but not saturated) prior to application to prevent premature drying.
Waterproof Wall Finishes in Bathrooms and Showers (Section 9.29.2)
To prevent moisture damage to the structural framing, the OBC mandates specific heights for waterproof finishes in wet areas. This is a critical step for empcontracting.ca Inc. your construction contractor in London, Ontario, when performing bathroom renovations.
Required Waterproofing Heights
- Shower Stalls: Waterproofing must extend at least 1.8 m above the floor.
- Bathtubs with Showers: Waterproofing must reach at least 1.2 m above the bathtub rim.
- Standard Bathtubs: A minimum height of 400 mm above the rim is required for tubs without shower heads.
Approved Waterproofing Materials
Per OBC 9.29.2.2, acceptable materials include ceramic, plastic, or metal tiles, sheet vinyl, tempered hardboard, laminated thermosetting decorative sheets, and linoleum. Selecting the right material ensures compliance and long-term performance.
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.