OBC Masonry Standards: Grout, Mortar, and Structural Support Guidelines for London, Ontario
Sarah's Expert Insight
OBC Compliance Specialist
"At empcontracting.ca Inc., we emphasize that precise mortar joint thickness and lintel selection are the primary defenses against structural settling in London and Oakville. In high-exposure areas like Muskoka, following these exact grout proportions is critical for preventing moisture-related masonry failure during the harsh freeze-thaw cycles."
When executing masonry work, adhering to the 2024 Ontario Building Code (OBC) is essential for structural durability. As empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure every project meets these rigorous safety and performance standards.
9.20.3.2. Grout Mix Proportions
Proper grout consistency is vital for structural reinforcement. According to Table 9.20.3.2.-C, grout must consist of 1 part Portland Cement, 0 to 1/10 parts Lime, and specific aggregate ratios:
- Fine Aggregate (Sand): 2¼ to 3 times the sum of cement and lime volumes.
- Coarse Aggregate: 1 to 2 times the sum of cement and lime volumes.
9.20.4. Mortar Joint Specifications
9.20.4.1. Thickness and Tolerances
Standard mortar joint thickness for burned clay brick and concrete masonry units is 10 mm. The OBC allows for specific tolerances in head and bed joints, ranging from -5 mm to +10 mm.
9.20.4.2. Proper Laying of Masonry Units
Hollow masonry units must be laid with mortar on both inner and outer face shells. Furthermore, vertically aligned webs must be laid in a full bed of mortar at the starting course, in all columns, and adjacent to cells intended for grout. Solid units require full head and bed joints, except where weep holes are necessary for ventilation.
9.20.5. Masonry Support and Lintels
9.20.5.1. Structural Support Requirements
All masonry must be supported by masonry, concrete, or steel. An exception is made for masonry veneer walls, which may be supported on wood frame foundations if they conform to specific OBC frame construction sentences. Additionally, masonry walls must be at least as thick as the wall they are supporting.
9.20.5.2. Lintels and Arches
To maintain integrity over openings, masonry must be supported by steel, reinforced concrete lintels, or masonry arches. Steel angle lintels must strictly conform to the prescribed tables in the 2024 Building Code Compendium to ensure they can handle the imposed loads of the structure.
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.