Replacing a flat roof in Montreal typically costs about $9.50 to $15 per square foot before taxes for an elastomeric membrane, and about $7 to $12 for TPO or EPDM, including tear-off. For a 1,200 sq ft plex roof, budget roughly $11,000 to $18,000 before taxes with elastomeric. Added insulation can cost another $2 to $8 per square foot.
Most duplexes, triplexes and small buildings in Montreal have flat roofs. Here are realistic benchmarks to budget and spot a quote that doesn’t add up.
Price per square foot by roof type
| Roofing | Typical price before taxes | Typical lifespan |
|---|---|---|
| Tar and gravel (built-up) | $7 to $12 / sq ft | 15 to 25 years |
| Elastomeric (two-ply) | $9.50 to $15 / sq ft | 25 to 40 years |
| TPO | $7 to $12 / sq ft | 15 to 35 years |
| EPDM | $9 to $12 / sq ft | 15 to 35 years |
What drives the bill
- Layers to remove and the condition of the roof deck
- Details: every drain, chimney, vent and skylight needs careful flashing. See flat roof flashing.
- Access: narrow lanes, height, crane or hoist
- Colour requirements in many boroughs. See white roofs in Montreal.
Before replacing everything, check whether a repair would do: repair or replace a flat roof. Then use our 10 questions for a roofer.
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Service: roofing quotes · Version française
Indicative prices before taxes (GST 5% and QST 9.975%), based on Quebec market ranges in 2025 and 2026. Only written quotes give your actual price.