2024 Ontario Building Code: Mortar and Grout Mix Standards for Masonry in London, Ontario
Sarah's Expert Insight
OBC Compliance Specialist
"Correct mortar selection is vital in regions like London and Muskoka, where freeze-thaw cycles can cause inferior mixes to crack and spall within just a few seasons. At empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize strict adherence to the 1.5-hour placement rule during our humid summers to ensure the chemical bond of the masonry remains uncompromised for the lifetime of the structure."
Understanding OBC Section 9.20.3.2: Mortar and Grout Requirements
In accordance with the 2024 Ontario Building Code (OBC), specifically section 9.20.3.2, ensuring the correct chemical composition and application of mortar and grout is essential for structural durability. Whether you are building load-bearing walls or decorative masonry veneer, compliance with these standards prevents long-term structural failure.
Mortar Types and Their Applications (Table 9.20.3.2.-A)
The OBC classifies mortar based on its location and the structural load it supports. For exterior load-bearing walls and foundation walls below ground, Type S mortar is mandatory due to its higher compressive strength. For interior non-loadbearing walls, Type N mortar is generally sufficient. Using the incorrect type can compromise the moisture resistance and strength of the assembly.
Strict Mixing and Placement Timelines
Temperature plays a critical role in masonry work. Sentence 9.20.3.2.(5) dictates that mortar must be placed in its final position within:
- 1.5 hours after mixing when the air temperature is 25°C or higher.
- 2.5 hours after mixing when the air temperature is less than 25°C.
Failure to adhere to these windows can result in "retempering" issues, where the mortar loses its bond strength, a common concern for projects in the variable climates of Southern Ontario.
Proportioning and Grout Standards
Grout for reinforced masonry must be mixed to ensure a suitable flow to fill all voids without segregation. At empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure that all mixes follow the precise volume proportions of Portland cement, lime, and fine aggregate defined in Table 9.20.3.2.-B to ensure peak performance and building inspector approval.
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.