Metal Roofing in Ontario: Structural Design & OBC Requirements

Metal roofing has become one of the most durable and energy-efficient solutions for Ontario’s demanding climate. Withstanding heavy snow, ice, and wind while offering sleek aesthetics, it’s no surprise that metal roofs are increasingly popular among homeowners and builders alike.

Compared to asphalt shingles, a properly engineered and installed metal roof in Ontario can last 40–70 years, providing low maintenance, energy savings, and long-term value.

1. Why Metal Roofing Matters in Ontario

Ontario’s climate poses unique challenges, from freeze–thaw cycles to snow accumulation and wind uplift. Metal roofing systems are designed to endure these extremes while maintaining watertight integrity and structural performance.

Key benefits include:

• Longevity: Up to 70 years with proper coatings and maintenance.

• Durability: Resists corrosion, impact, and deformation.

• Energy Efficiency: Reflective coatings reduce cooling loads.

• Low Maintenance: Minimal repairs compared to shingles or flat roofs.

Beyond appearance, a metal roof is an engineered system, one that must comply with the Ontario Building Code (OBC) to ensure strength, safety, and environmental performance.

2. Metal Roofing Types: Corrugated, Standing Seam, and Shingles

Ontario builders and homeowners can choose from several types of metal roofing, each with distinct cost, performance, and aesthetic profiles.

Corrugated Metal Roof

The most economical and lightweight option, ideal for utility buildings and cost-sensitive projects.

• Lifespan: 30–45 years

• Pros: Affordable, quick installation

• Considerations: Requires high-quality underlayment to prevent condensation

Standing Seam Metal Roof

Featuring interlocking vertical seams, these systems provide exceptional watertightness and clean, modern lines.

• Lifespan: 40–60 years

• Pros: Superior weather resistance, suitable for low-slope roofs

• Considerations: Higher cost but excellent long-term performance

Metal Shingles (Stone-Coated or Steel)

Combines the appearance of slate or tile with the strength of steel.

• Lifespan: 50+ years

• Pros: Premium aesthetics and high durability

• Considerations: Framing must be verified to support all OBC snow and dead loads.

3. Ontario Metal Roofing Cost and Performance Comparison

Feature	Corrugated Panels	Standing Seam	Metal Shingles
Appearance	Industrial/rustic	Modern/clean	Premium/slate-like
Durability	30–45 years	40–60 years	50–75 years
Cost	Most affordable	Moderate	Most expensive
Wind Resistance	90–110 mph	90–110 mph	150+ mph
Best Use	Budget/utility	Residential	Premium/custom

While metal roofing has a higher upfront cost than asphalt shingles, its extended lifespan and minimal maintenance make it a cost-effective choice in the long run.

4. Engineering & OBC Design Considerations

Installing a metal roof in Ontario involves more than choosing panels. To ensure compliance and performance, engineers and contractors must account for both building science and Ontario Building Code (OBC) requirements.

Key OBC Considerations:

• Load Capacity: The roof framing must be verified to support the total dead load (including any existing roofing layers) plus the specified OBC Part 9 or Part 4 snow loads.

• Fasteners and Clips: Use CSA-approved components to accommodate expansion and contraction.

• Ventilation: Proper attic ventilation prevents condensation and corrosion.

• Underlayment & Sealants: High-quality underlayment, protective coatings, and snow guards are required for water and ice protection.

OBC also requires that roofs resist wind uplift, snow loads, and moisture infiltration, ensuring long-term structural reliability and occupant safety.

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Ensure Your Metal Roof Meets OBC Standards

We help builders and designers verify roof load capacity, fastener design, and compliance details before installation.

Talk to an Engineer

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5. Performance in Ontario’s Climate

Metal roofs perform exceptionally well across Ontario’s regions, from Lake Ontario’s moisture-heavy winters to Northern Ontario’s heavy snow zones.

They offer:

• Snow and ice shedding to reduce structural stress

• Reflective surfaces that lower cooling costs

• Corrosion resistance with galvanized or coated finishes

• Extended service life with minimal environmental impact

For low-slope roofs, standing seam systems with double underlayment and proper drainage detailing are highly recommended to prevent leaks and ensure OBC compliance.

Conclusion: Building a Roof That Lasts

A metal roof in Ontario is not just a cosmetic choice; it's an engineered shield against decades of snow, ice, and wind. Complying with the OBC for wind uplift and load capacity isn't just about passing inspection—it's the very foundation of a 50-year service life.

Proper engineering, from fastener selection to ventilation and load verification, ensures your roof meets both structural and long-term performance standards.

At Parsways Inc., we look beyond the panels and fasteners. We engineer a complete, resilient roofing system, ensuring your design is not just compliant on paper, but performs flawlessly through every Ontario storm for decades to come.

Co-authored by Hoda Rajaeizadeh and Negin Amani.