2024 Ontario Building Code Stucco Lath & Fastening Standards | empcontracting.ca Inc.
Sarah's Expert Insight
OBC Compliance Specialist
"Adhering to the precise fastening and furring requirements of OBC 9.28.4 is essential for preventing delamination in the diverse climates of London, Oakville, and Muskoka. At empcontracting.ca Inc. your construction contractor in London, Ontario, we emphasize the 6mm self-furring requirement to ensure full stucco encapsulation, which is the best defense against the moisture-driven expansion and contraction typical of Ontario's freeze-thaw cycles."
Comprehensive Guide to OBC Stucco Lath and Fastening (Section 9.28.4)
For high-quality exterior finishes in Ontario, adhering to the 2024 Building Code Compendium is non-negotiable. As empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize these technical requirements to ensure structural integrity and aesthetic longevity for every project.
OBC 9.28.4.2 & 9.28.4.3: Sheathing and Lath Material Specifications
Under Subsection 9.28.4.2, sheathing may be omitted beneath stucco if specific galvanized wire (1.19 mm diam) is applied horizontally or if paper-backed welded wire metal lath is utilized. According to Table 9.28.4.3, vertical surfaces require welded or woven wire with specific minimum diameters ranging from 1.15 mm to 1.50 mm, or expanded metal stucco mesh with a minimum mass of 0.98 kg/m².
OBC 9.28.4.4 & 9.28.4.5: Spacing, Furring, and Application Methods
To ensure proper stucco embedment, OBC 9.28.4.4 mandates that lath be held at least 6 mm away from the backing using self-furring devices. During application (9.28.4.5), lath must be installed with the long dimension horizontal and joints lapped by at least 50 mm. End joints must be staggered over framing members, and external corners require reinforcement extending 150 mm on both sides to prevent structural cracking at the edges.
OBC 9.28.4.6: Precision Fastening Standards
Fastening is strictly regulated by Subsection 9.27.5. For vertical surfaces, the code requires specific spacing: either 150 mm o.c. vertically and 400 mm o.c. horizontally, or 100 mm o.c. vertically and 600 mm o.c. horizontally. These precise measurements are vital for wind load resistance and the overall durability of the exterior envelope.
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.