NBC 2025 Guide to Roofing Materials and Asphalt Shingle Installation in London, Ontario
Sarah's Expert Insight
Senior Consultant at empcontracting.ca Inc.
"The NBC 2025 updates place a significant emphasis on climate resilience, particularly regarding eave protection and fastener schedules in high-moisture zones like London. By strictly adhering to these standards, empcontracting.ca Inc. your construction contractor in London, Ontario ensures that homeowners are protected from the costly secondary damages of ice damming and shingle blow-offs that are becoming more common in our shifting regional climate."
Ensuring compliance with the National Building Code of Canada (NBC) 2025 is essential for maintaining structural integrity and insurance validity for residential properties. At empcontracting.ca Inc. your construction contractor in London, Ontario, we specialize in implementing these updated standards to protect your home against the unique Southwestern Ontario climate.
Standard Compliance for Roofing Materials
The NBC 2025 mandates that all asphalt shingles must conform to the CSA A123.5 standard. This ensures that the shingles possess the necessary physical properties to resist water penetration, fire spread, and accelerated aging due to UV exposure. Using non-certified materials can lead to premature failure and may void manufacturer warranties.
Roof Slope and Underlayment Requirements
Installation techniques under the NBC 2025 vary based on the roof's pitch. For low-slope roofs (between 1:6 and 1:3), specific double-coverage underlayment is required to prevent water ingress. For standard slopes (1:3 or greater), a single layer of approved underlayment is typically sufficient, provided it is installed with the correct overlap to facilitate proper drainage.
Eave Protection and Ice Damming Prevention
In regions like London, Ontario, where freeze-thaw cycles are frequent, eave protection is a critical code requirement. The NBC 2025 requires a water-shedding membrane to extend from the edge of the roof to at least 900 mm (36 inches) up the roof slope, reaching a point at least 300 mm (12 inches) beyond the interior face of the exterior wall. This prevents moisture from backing up under shingles during ice damming events.
Fastening and Wind Resistance Standards
Proper fastening is the cornerstone of wind resistance. The 2025 code specifies that shingles must be secured with a minimum of four fasteners per strip, though empcontracting.ca Inc. your construction contractor in London, Ontario often recommends six fasteners in high-wind areas to exceed minimum safety thresholds. Fasteners must be corrosion-resistant and driven straight and flush with the shingle surface to avoid tearing or lifting.
Professional Consultation
Navigating the technical nuances of the NBC 2025 requires professional oversight. From selecting the right granule adhesion ratings to ensuring proper attic ventilation—which works in tandem with roofing to prevent deck rot—expert installation is the only way to guarantee code compliance.