OBC Masonry Moisture Protection & Winter Construction Standards: London Contractor Guide
Sarah's Expert Insight
OBC Compliance Specialist
"Adhering to the 5°C minimum temperature rule is vital for the longevity of builds in London and Muskoka, where sudden temperature drops can compromise mortar integrity if not properly shielded. At empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize precision in parging and drip-edge installation to ensure interior finishes remain moisture-free throughout Oakville's humid seasons and the harsh northern winters."
When executing masonry work, adhering to the 2024 Ontario Building Code (OBC) is essential for structural longevity and moisture control. As empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure every project meets these rigorous standards for interior and exterior protection.
9.20.13. Protection of Interior Finish and Drainage
Moisture Barriers for Interior Surfaces
Per Section 9.20.13.9, interior finishes on exterior masonry walls (excluding cavity walls or those protected by porch roofs) must be protected from moisture damage. This requires the interior surface to be parged and covered with No. 15 breather-type asphalt-saturated paper. However, these requirements are waived if waterproof adhesive-applied insulation effectively limits water vapour passage.
Preventing Water Accumulation
To maintain a dry interior environment, flashing must be installed where water might accumulate to direct it outside. Additionally, cavity walls must be kept clear of mortar droppings to prevent moisture bridging, and all door and window junctions must be professionally caulked. Window sills require a 25 mm drip and an outward slope to shed water unless concealed flashing is present.
9.20.14. Professional Protection During Construction
Temperature and Mortar Integrity
Temperature control is critical for masonry strength. The OBC dictates that mortar and masonry must be maintained at a minimum of 5°C during installation and for at least 48 hours afterward. The use of frozen materials in any mortar mix is strictly prohibited to prevent structural failure.
Weather Shielding Requirements
Uncompleted masonry must never be left exposed to the elements. Section 9.20.14.2 requires that the top surface of any unfinished wall be completely covered with waterproofing material when work is not actively in progress to prevent saturation and freeze-thaw damage.
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.