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Mansard Roof Cost Calculator

Estimate Canadian 2026 mansard roof cost by lower-face area, upper-deck area, materials, dormer count, storey and access. Aligns with NBC 2020 Part 9 9.26, CSA A123 series, CRCA Roofing Specs Manual, provincial heritage Acts.

Mansard Roof Cost Calculator

Estimate Canadian 2026 mansard roof cost by lower-face area, upper-deck area, materials, dormer count, storey and access. Lower steep face priced as pitched roofing; upper deck priced as low-slope membrane. Aligns with NBC 2020 Part 9 9.26, CSA A123 series, CRCA Roofing Specs Manual.

Estimated mansard roof cost
$32,450
Range: $27,583 – $38,940
steep lower face + low-slope upper deck + dormers + tear-off + permit + disposal
Lower face
$16,800
Upper deck
$6,900
Dormers
$1,680
Tear-off
$3,920
Permit
$240
Disposal
$540

What this calculator estimates

This calculator quotes the all-in installed cost for a 2026 Canadian mansard roof project. It separates the bill into:

  • Steep lower face (brisis) — pitched-roof material on the 65-75° lower section, priced at roughly 2× the per-sq-ft rate of a standard 5/12 pitched roof in the same material.
  • Flat upper deck (terrasson) — single-ply or SBS modified bitumen membrane on the 5-10° upper section.
  • Dormers — per-dormer flashing scope.
  • Tear-off — removal of existing covering on both sections.
  • Permit — municipal building permit + heritage permit where applicable.
  • Disposal — bin / tip fee.
  • Weekend / out-of-hours premium.

Minimum mobilisation charge CAD 1,750 applies for most Canadian metro mansard projects.

How to use it

  1. Measure the brisis area in sq ft — perimeter (lf) × break height (ft) × 1.06 (70° slope factor).
  2. Measure the terrasson area in sq ft — building footprint minus brisis footprint projection.
  3. Pick the lower-face material — slate is the heritage default; standing-seam metal for Old Quebec; cedar shake for rural Eastern Townships farmhouses.
  4. Pick the upper-deck membrane — SBS modified bitumen is the dominant Canadian system; TPO or BUR alternatives.
  5. Set dormer count.
  6. Set storey count — most Canadian heritage mansards are two-storey-plus-mansard.
  7. Pick access tier.
  8. Toggle add-ons.

Typical 2026 Canadian mansard cost ranges

Scope (two-storey base, moderate access, 4 dormers, tear-off + permit + bin)2026 installed price
Small mansard (1,000 sq ft brisis + 800 sq ft terrasson, asphalt + SBS)CAD 19,000 – 28,000
Standard mansard (1,600 sq ft brisis + 1,200 sq ft terrasson, slate + SBS)CAD 30,000 – 52,000
Standard mansard, copper standing-seam + lead terrasson (Vieux-Québec)CAD 95,000 – 145,000
Standard mansard, ferblantier tin + SBS (Old Quebec heritage)CAD 58,000 – 88,000
Large institutional (3,200 sq ft brisis + 2,400 sq ft terrasson, slate + BUR)CAD 95,000 – 155,000
Slate brisis upgrade over asphalt baseline+85% on lower-face line
Copper standing-seam upgrade+25% on lower-face line
Each additional dormer+CAD 420
Tear-off+CAD 1.40 / sq ft combined

Add 15% for two-storey access, 35% for three-storey or higher.

Cost drivers

Brisis material. Quebec, Welsh or Vermont natural slate is the heritage default for Old Quebec, Plateau Mont-Royal, Westmount, Old Toronto, Old Ottawa. Standing-seam copper or zinc is the historic alternative — Vieux-Québec used local ferblantier tin sheet, and Vicwest and AG Panel produce period-correct replicas. Eastern white cedar shake is appropriate on rural Second Empire farmhouses in the Eastern Townships, Hudson Valley equivalent in eastern Ontario. Asphalt architectural shingle is the modern budget option, generally refused in Vieux-Québec and heritage conservation districts but acceptable on non-listed properties.

Labour premium. 2× the per-sq-ft rate of a standard 5/12 pitched roof. CNESST/MOL/WorkSafeBC fall-arrest mandates, slow slate-laying cadence on 70° face, high cut-and-fit waste around dormers.

Terrasson membrane. SBS modified bitumen (Soprema Sopralène, IKO Torchflex, Bauder K5K) is the dominant Canadian flat-roof system and the modern default. TPO is gaining adoption (Sika Sarnafil G, Carlisle Sure-Flex). Traditional lead or tin sheet is required for the most sensitive Vieux-Québec UNESCO properties.

Dormer count. CAD 380-500 per dormer for the flashing scope. Round-top eyebrow dormers add CAD 200-350 each.

Vieux-Québec UNESCO restrictions. The Vieux-Québec Historic District is the only UNESCO World Heritage Site in North America with a continuously-occupied 17th-19th century urban fabric. Reroofing within the district requires Commission d’urbanisme et de conservation de Québec approval; the assessment regime is the most restrictive in Canada. Plan 12-20 weeks for heritage approval.

Provincial OHS. CNESST notice required in Quebec for fall-arrest work; MOL Notice of Project required in Ontario for work above 30 person-days. WorkSafeBC, AB OHS, etc. have equivalent requirements.

Per-locale data sources

Canadian figures are sourced from:

  • CRCA (Canadian Roofing Contractors Association) 2026 Roofing Market Report.
  • CASMA Architectural Sheet Metal Manual 2026 for standing-seam metal pricing.
  • Renomii 2026 cost data.
  • HomeStars 2026 pricing.
  • Glendyne Slate (Quebec) and Camara Slate (Vermont) producer pricing.
  • Vicwest, IDEAL Roofing, AG Panel, Westform for standing-seam metal.
  • Soprema, IKO, Bauder for SBS modified bitumen.
  • Sika Sarnafil Canada, Carlisle, Bauder for TPO.
  • Commission d’urbanisme et de conservation de Québec, Heritage Toronto, Heritage Ottawa planning guidance.
  • Q1 2026 contractor quotes from Montreal H2W/H3Y/H3Z, Quebec G1R/G1S, Toronto M5R/M4W/M5T, Ottawa K1N/K1S postal codes.

Related calculators: slate roof cost calculator, TPO roof cost calculator, flat roof replacement cost calculator, dormer installation cost calculator.

When to call a contractor

Canadian mansard reroofing is not a DIY scope. CNESST/MOL/WorkSafeBC fall-arrest scaffold mandate, heritage conservation district permit requirement, and dual-skill steep-and-low-slope crew requirement all put this work in the licensed contractor category with heritage experience. Appoint a CRCA-member contractor with documented heritage mansard experience; request written scope referencing CSA A123.5 (asphalt shingle), CSA A123.4 (slate), CSA A123.21 (TPO), CSA A123.3 (SBS), and the applicable provincial heritage Act; verify provincial contractor licence (RBQ in Quebec, OCOT in Ontario) and CCQ documentation before signing.

Frequently asked questions

How much does a mansard roof cost in Canada in 2026?
A typical Canadian mansard reroof in 2026 costs CAD 30,000 to CAD 52,000 for a 2,800 sq ft total roof (1,600 sq ft steep lower face + 1,200 sq ft flat upper deck) with Quebec or Welsh natural slate on the brisis, SBS modified bitumen on the terrasson, four dormers, two-storey base, moderate access, full tear-off, municipal building permit and disposal bin. Canadian mansards are concentrated in Old Quebec City (Vieux-Québec UNESCO World Heritage Site), Montreal (Plateau Mont-Royal, Westmount), Old Toronto (Cabbagetown, Annex, Yorkville), and Old Ottawa (Sandy Hill, New Edinburgh). Most sit within a provincial heritage register or municipal heritage conservation district. Source: CRCA 2026 Roofing Market Report, CASMA Architectural Sheet Metal Manual, Renomii 2026 cost data, Q1 2026 quotes from Montreal H2W/H3Y, Quebec G1R, Toronto M5R/M4W, Ottawa K1N postal codes.
Are mansards heritage-protected in Canada?
Many are. Three main Canadian mansard stocks sit within heritage protection regimes: (1) Old Quebec (Vieux-Québec) UNESCO World Heritage Site — every reroof within the historic district requires approval from the Quebec Ministère de la Culture under the Loi sur le patrimoine culturel and from the Commission d'urbanisme et de conservation de Québec. (2) Montreal Plateau and Westmount — heritage conservation regimes under the Quebec heritage Act and municipal by-laws. (3) Toronto and Ottawa heritage conservation districts — Ontario Heritage Act Part V designations requiring Heritage Permit applications. Material substitution from original slate to asphalt is frequently refused; slate-replacement-in-kind matching original colour, dimensions and exposure is fast-tracked. Provincial heritage Acts also apply: Loi sur le patrimoine culturel (QC), Ontario Heritage Act (ON), Heritage Property Act (NS), New Brunswick Heritage Conservation Act.
Why does the lower steep face cost so much more per sq ft?
Three reasons. (1) Fall hazard. Provincial OHS regulations (CNESST in Quebec, MOL in Ontario, OHS BC, AB OHS, etc.) require fall arrest above 3 m on residential roofs and above 2.4 m on commercial; a 70° brisis triggers maximum fall-protection scope. (2) Installation speed. On a 4/12 pitched roof a slater can lay 4-5 sq ft per day per worker; on a 70° brisis that drops to 1.5-2 sq ft per day. (3) Material waste. Mansard brisis sections wrap dormers and corners; cut-and-fit waste runs 15-20% versus 8% on a standard pitched roof. The cumulative effect is roughly a 2× per-sq-ft labour premium over an equivalent 5/12 pitched roof in the same material.
What materials are appropriate for a Canadian mansard brisis?
Canadian heritage assessments narrow the choice to: (1) Natural slate — Quebec (Glendyne / Slate Valley), Welsh (Penrhyn, Ffestiniog), or Vermont (Camara Slate) — the heritage default. Adds 85% to lower-face cost over asphalt. (2) Standing-seam metal — copper, zinc, or pre-painted steel (Vicwest, IDEAL Roofing, AG Panel, Westform). Adds 25%. The historic Old Quebec mansards used local tin sheet (matériel ferblantier) — Vicwest and AG Panel produce period-correct replicas. (3) Eastern white cedar shake — for rural Second Empire farmhouses in Eastern Townships and rural Ontario. Adds 30%. (4) Asphalt architectural shingle — modern budget option; generally refused in Old Quebec, Plateau Mont-Royal, Westmount, Toronto and Ottawa heritage conservation districts but accepted on non-listed properties. (5) Clay tile is rare in Canada outside French-Canadian mediterranean revivals.
What goes on the flat upper deck (terrasson)?
The terrasson uses standard Canadian low-slope membrane systems: SBS modified bitumen (the dominant Canadian flat-roof system — Soprema Sopralène, IKO Torchflex, Bauder K5K), TPO single-ply (Sika Sarnafil G, Carlisle Sure-Flex, IKO Armourplan), EPDM rubber, or BUR 4-ply hot-asphalt gravel. CSA A123.21/22 and CCMC evaluations cover product compliance. On Old Quebec UNESCO properties, traditional ferblantier tin sheet at 24-26 ga or lead sheet is required for the most sensitive buildings. The brisis-to-terrasson transition is the most critical detail — water from the flat deck must be diverted off the front of the brisis without ponding. NBC 9.26 covers the principles; specify a continuous transition flashing in lead, tin or matching welded membrane.
What does a municipal building permit cost in Canada?
Permit costs vary by municipality. Indicative 2026 figures: Quebec City (Vieux-Québec) CAD 450-850 building permit + CAD 240-580 heritage Commission d'urbanisme review. Montreal CAD 280-520 building permit + CAD 180-380 heritage application. Toronto CAD 350-650 building permit + CAD 220-450 Heritage Permit (Toronto Preservation Board). Ottawa CAD 260-440 building permit + CAD 180-340 Built Heritage Sub-Committee. Plan 8-16 weeks for heritage approval in Vieux-Québec; 4-10 weeks in other heritage districts; 2-4 weeks for non-heritage building permits. Mandatory CNESST notice for fall-arrest work in Quebec; MOL Notice of Project for similar Ontario work above 30 person-days.
Do I need scaffold for a Canadian mansard reroof?
Yes. CNESST (Quebec), MOL (Ontario), WorkSafeBC, OHS Alberta, and other provincial OHS authorities require fall protection for work above 3 m on residential and 2.4 m on commercial roofs. A 70° brisis is functionally a wall and requires scaffold with edge protection. For terraced Plateau Mont-Royal, Westmount, Old Toronto and Old Ottawa mansards, scaffold typically sits in the front yard or on the city sidewalk and requires a sidewalk occupancy permit. Quebec City Vieux-Québec is the most restrictive — permits are issued for limited hours only to preserve the UNESCO World Heritage Site visitor experience. Plan 4-8 weeks for scaffold-and-permit lead time.
Is there tax relief for Canadian heritage reroofing?
Two narrow Canadian options. (1) Form T776 capital cost allowance — for income-producing properties (rental, mixed-use), the reroof cost is added to the building's Class 1 capital cost allowance pool at 4% per year, declining balance. (2) Provincial heritage grants — Quebec Programme de soutien à la restauration du patrimoine immobilier (typically CAD 5,000-50,000 per project for individually-listed properties), Ontario Heritage Trust grants, Heritage Canada Foundation. Federal Historic Places Program no longer funds reroofing directly. For owner-occupied heritage mansards, no direct tax relief is available beyond standard maintenance deductions on rental portions of the property. The GST/HST New Housing Rebate does NOT apply to heritage reroofing.

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