Ontario Building Code Standards for Wood Shingles and Cedar Shakes | empcontracting.ca Inc.
Sarah's Expert Insight
OBC Compliance Specialist
"Properly executing the underlay interlaying requirements of OBC 9.26.10.2 is essential for long-term roof durability in the volatile climates of London, Oakville, and Muskoka. As empcontracting.ca Inc., your construction contractor in London, Ontario, we ensure every cedar shake installation adheres to these strict fastening and exposure standards to mitigate the risks of moisture penetration and high-wind uplift common in Southwestern Ontario."
When installing traditional roofing materials in Ontario, adhering to the 2024 Building Code Compendium (Section 9.26) is vital for structural integrity and moisture protection. Below is a detailed breakdown of the requirements for wood shingles and cedar shakes to ensure compliance and longevity.
9.26.9. Wood Shingles: Fastening and Exposure
Fastening Requirements (9.26.9.5.)
To ensure stability, wood shingles must be secured with a minimum of two nails or staples. These fasteners should be positioned approximately 20 mm from the lateral sides of the shingle and 40 mm above the exposure line.
Determining Shingle Exposure (9.26.9.6.)
The maximum exposure of wood shingles is determined by the roof slope and the grade/length of the shingle. For a standard 450 mm No. 1 Grade shingle:
- Slopes less than 1 in 3: Maximum exposure of 115 mm.
- Slopes 1 in 3 or steeper: Maximum exposure of 140 mm.
Proper flashing and eave protection must also conform to subsections 9.26.4. and 9.26.5. respectively.
9.26.10. Cedar Roof Shakes: Installation and Underlay
Size and Thickness (9.26.10.1.)
Cedar shakes must meet specific dimensions to be code-compliant: a minimum length of 450 mm, a width between 100 mm and 350 mm, and a butt thickness ranging from 9 mm to 32 mm.
Mandatory Underlay and Interlaying (9.26.10.2.)
The installation of cedar shakes requires rigorous moisture barriers:
- Eave Protection: If standard eave protection is absent, a 900 mm wide strip of underlay must be installed along the eaves.
- Interlaying Strips: A strip of underlayment (minimum 450 mm wide) must be interlaid between every course of shakes. The bottom edge of this strip must be placed above the butt line at a distance equal to double the exposure of the shakes.
- Hips and Ridges: Interlaid strips must lap at least 150 mm at hips and ridges to prevent water ingress to the roof sheathing.
For professional installation that meets these rigorous standards, trust empcontracting.ca Inc. your construction contractor in London, Ontario.
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.