Best Commercial Roofing Contractors in Toronto

Commercial and industrial roofing in Toronto covers offices, retail centres, warehouses, and multi-unit buildings — most using low-slope membrane systems such as TPO, EPDM, and modified bitumen. The 8 contractors below were selected from our full Toronto top 10 as the strongest for commercial work, ranked by experience, manufacturer certifications, BBB standing, and verified reputation.

Toronto's commercial roofing market is defined by density and complexity. Downtown core buildings — the Financial District, King West, Liberty Village, and the East Bayfront redevelopment — require roofing contractors with crane logistics experience, knowledge of Toronto's noise by-law restrictions on construction hours, and familiarity with the City's Green Roof Bylaw (Chapter 492), which mandates green roof coverage on new commercial, institutional, and residential buildings above certain size thresholds. The green roof requirement affects both new construction specifications and re-roofing feasibility on older structures undergoing substantial renovation.

Across the inner suburbs — Etobicoke, North York, Scarborough — the commercial stock is predominantly 1960s–1990s flat-roof buildings with built-up roofing or early single-ply EPDM. These are at end-of-life in large numbers and transitioning to TPO and modified bitumen replacements. Ontario's Building Code requires R-31 effective insulation for commercial roofs, and re-roofing triggers this requirement in many jurisdictions — the insulation upgrade cost is a significant line item in Toronto commercial project budgets.

Buildoreno's GTA flat roof cost guide for 2026 places modified bitumen at CAD $5–$8 per square foot and TPO at CAD $7–$12 per square foot installed, with most GTA flat roofing projects landing between CAD $8,000 and $25,000; Garcia Roofing's Ontario commercial guide puts the broader range at CAD $8–$18+ per square foot (modified bitumen $10–$16, TPO $8–$14), with GTA labour at the high end of Ontario regional pricing.

How many commercial roofing contractors are in Toronto?

Our directory lists 8 independently verified commercial roofing contractors serving Toronto, Ontario, ranked by experience, certifications and reputation. Dominion Roofing is ranked #1. There are no paid placements.

How do I choose a commercial roofer in Toronto?

Confirm licensing and insurance for Ontario, ask for commercial project references in Toronto, get multiple written quotes, and check each contractor's BBB standing. Every company listed here has been independently researched.

Does Toronto's Green Roof Bylaw apply to re-roofing projects?

The Green Roof Bylaw applies to new building permit applications — typically triggered when more than 50% of a building's value is being added or altered. A straightforward like-for-like re-roofing of an existing commercial building generally does not trigger the bylaw. However, any addition, major renovation, or change of use that requires a full building permit review may trigger compliance. The City of Toronto's Building Division can confirm applicability for your specific project before permit application.

What insulation R-value is required for commercial roofs in Toronto?

Ontario's Building Code (OBC 2024) requires a minimum RSI-5.5 (approximately R-31) effective thermal resistance for commercial roof assemblies in Toronto's climate zone. This is typically achieved with 5–6 inches of polyisocyanurate insulation board, derated for cold-weather performance. The code's effective R-value requirement means the complete assembly — including structural deck and air barrier — is assessed together. GTA contractors familiar with RoofNav assembly specification tools can generate code-compliance documentation as part of the project package.

How long does a commercial roof replacement take in Toronto's dense urban environment?

A typical suburban Toronto commercial roof replacement on a 20,000 sq ft building takes five to ten working days in good weather. Downtown core projects take significantly longer due to crane permit timelines (Toronto Right-of-Way permits can take two to four weeks to obtain), staging constraints, noise by-law compliance windows (construction typically restricted to 7am–7pm weekdays), and union contract requirements. Building owners with lease revenue at risk should account for extended timelines and negotiate contractor scheduling commitments in writing before signing.