Insulation & R-Value Requirements
Most modern building codes require minimum insulation values based on climate zone and whether the roof is above conditioned space. In Calgary, commercial flat roofs typically need continuous insulation above the deck to meet energy code requirements.
- Verify the required effective R-value for your building type and climate zone.
- Use compatible insulation (e.g., polyiso, EPS, mineral wool) that is approved for use in roof assemblies.
- Coordinate vapor barrier location based on interior humidity and climate to avoid condensation.
Fire & Wind Performance
Roofing systems are generally required to meet specific fire and wind uplift ratings when tested as part of a complete assembly. This is especially important on commercial buildings and densely built urban areas.
- Confirm the required roof covering fire classification (e.g., Class A) for your building type.
- Use assemblies that have tested wind uplift ratings suitable for local wind speeds and exposure.
- Ensure perimeter and corner attachment patterns follow the tested assembly or manufacturer guidelines.
Roof Slope & Drainage
Building codes require roofs to drain water efficiently so that standing water does not create structural or durability issues. Minimum slopes and drainage requirements may differ for low-slope and steep-slope roofs.
- Provide minimum slope toward drains, scuppers, or gutters as required for low-slope roofs.
- Include overflow drains or emergency scuppers where required by code.
- Coordinate tapered insulation or crickets to move water away from walls, curbs, and penetrations.
Permits & Inspections
Many jurisdictions require permits for roof replacement, structural changes, or significant repairs. Smaller repairs may be exempt, but it is important to confirm with the local authority having jurisdiction (AHJ).
- Confirm when a roofing permit is required for your project.
- Understand inspection stages (e.g., in-progress, insulation, and final inspections).
- Maintain documentation such as drawings, specifications, and product approvals for review.
Approved Materials & Details
Codes typically list general performance requirements, while specific products and assemblies are approved through listings, evaluation reports, or manufacturer documentation.
- Use products with appropriate approvals or listings for the jurisdiction (e.g., CCMC, ICC-ES).
- Follow manufacturer installation instructions as part of code compliance.
- Ensure transitions, flashings, and edge details are designed and installed to be watertight.
Maintenance, Inspections & Lifecycle
While codes focus primarily on design and installation, many owners and property managers implement maintenance programs to extend roof life and reduce risk of leaks or failure.
- Schedule periodic roof inspections, especially after severe weather events.
- Keep drains, scuppers, and gutters clear of debris to maintain proper drainage.
- Document repairs and modifications to support warranty and future code reviews.
Disclaimer: This page is for general information only and does not replace the official building code or local bylaws. Always confirm requirements with the authority having jurisdiction and a qualified design professional.