Roof replacement cost in Ottawa
Quick answer
Compare roof squares, tear-off layers, how much ice and water shield is installed (eaves, valleys, penetrations), underlayment, ventilation plan, shingle or metal by brand and line, a per-sheet price for replacement decking, disposal, HST and written warranties. A lump sum can't be judged.
Ottawa's long winters, heavy snow and freeze-thaw cycles make ice dams and leaks at the eaves a common problem. That puts extra weight on the parts of a roof you can't see — ice and water membrane, underlayment and attic ventilation. Shingle choice matters, but the protection underneath is where good and weak quotes really separate. Metal roofs are also popular here for shedding snow.
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What most people miss
Ice dams are a ventilation problem as much as a roofing one
Ice dams form when warm attic air melts snow that refreezes at the cold eaves. More membrane at the edge limits leaks, but balanced intake and exhaust ventilation — and attic air sealing — addresses the cause. A quote that only adds membrane, without looking at soffit intake and roof vents, may treat the symptom. Ask every roofer how they're handling ventilation.
How this price is built
Roof size and pitch
Measured squares (100 sq ft each), pitch and waste factor. Steeper and more complex roofs cost more.
Tear-off
Number of existing layers removed and disposal.
Ice and water shield
Self-adhered membrane at eaves, valleys and around penetrations. How far up from the eaves matters.
Underlayment and decking
Synthetic underlayment over the rest of the roof, plus a per-sheet price for replacing rotten decking.
Ventilation
Soffit intake, ridge or box vents, and any attic air sealing or insulation work.
Roofing material
Architectural shingles by brand and line, or standing-seam or steel shingle metal.
Flashing, HST and warranty
Chimney, wall and valley flashing, whether HST is included, and manufacturer plus workmanship warranties.
What makes a quote high
Open-ended decking
Without a per-sheet price, replacement decking becomes an unlimited add-on. Get the unit price in writing.
Unnecessary full membrane
Full-roof membrane can be justified on low slopes, but on standard pitches it may be an expensive upsell. Ask why.
Premium shingle without explanation
Designer lines cost more. Make sure you're choosing it, not just being given it.
Winter emergency pricing
Mid-winter tear-offs carry risk and premiums. Unless there's an active leak, scheduling for spring through fall is usually better.
HST added late
Quotes that show HST differently can look 13% apart. Compare tax-included totals.
Itemised versus vague
A quote you can evaluate looks different from one you can't. This is what to look for, line by line.
| Item | A quote you can judge | A quote you can't |
|---|---|---|
| Size | Squares and pitch measured | Average roof |
| Membrane | Locations and coverage stated | Ice protection included |
| Ventilation | Intake and exhaust plan described | Vents as needed |
| Decking | Per-sheet price in writing | Extra if required |
| Material | Brand, line and colour named | Quality shingles |
Questions to ask before you approve
- How many squares, and how many layers are you tearing off?
- Where exactly are you installing ice and water shield?
- How are you handling ventilation and attic airflow?
- What's your per-sheet price for replacement decking?
- Is HST included, and what are the manufacturer and workmanship warranties?
What to ask an Ottawa roofer
Copy these lines as they are. Politeness plus specifics gets answers.
- 1.“Please itemize squares, tear-off, membrane locations, ventilation and shingle brand and line.”
- 2.“What's your per-sheet decking price?”
- 3.“Is HST included, and what are the written warranties?”
When a high price is legitimate
A higher-than-expected price isn't automatically a bad one. These are the situations where it's usually justified.
- Multiple existing layers or rotten decking must be removed.
- Past ice dam damage requires extended membrane coverage.
- Ventilation upgrades are needed to stop recurring ice dams.
- Heritage district rules require specific materials or approvals.
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Common questions
How much does a roof replacement cost in Ottawa?
It depends on squares, pitch, tear-off layers, membrane, ventilation, material and decking. Compare itemized quotes — this guide doesn't invent a city average.
Shingles or metal in Ottawa?
Architectural shingles cost less up front; metal sheds snow well and lasts longer but costs more. Get both prices if you're considering metal.
Do I need a permit to reroof in Ottawa?
Like-for-like reroofing generally doesn't need a building permit, but structural changes do, and heritage areas may have extra rules. Ask your roofer to confirm.
When is the best time to replace a roof in Ottawa?
Late spring through fall. Winter installs are possible with care, but booking early in the season usually means better scheduling.
Keep reading
How much should a roof replacement cost?
Squares, tear-off, decking, underlayment, flashing — why bids differ so much.
Contractor quotes
What to check across this whole category, wherever you are.
Roof replacement cost calculator
A quick estimate for before you have a quote in hand.
Cost per square foot calculator
A quick estimate for before you have a quote in hand.
Furnace replacement cost in Toronto
Efficiency tiers, venting changes, rental contracts versus ownership, rebates and winter emergency pricing.
Basement development cost in Calgary
Permits, egress, ceiling height, suite rules, radon and mechanical relocations — what changes the number.
Last reviewed September 2026. This guide explains how pricing is structured in general terms. It deliberately avoids quoting dollar figures, because fair pricing depends on your location, scope and market. Educational information only — not professional advice. See our disclaimer and browse the full cost guide library.