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Roof Deck Replacement Cost Calculator

2026 Canadian roof deck (sheathing) replacement cost by line item: OSB or CSP plywood, tear-off, ice-and-water shield to NBC 9.26.7, rafter sistering, fasteners, permit, and disposal. Real 2026 contractor rates per CRCA and NBC 2020.

Roof Deck Replacement Cost Calculator

2026 Canadian roof deck (sheathing) replacement cost by line item — OSB or CSP plywood board, tear-off, ice-and-water shield, rafter repair, fasteners, permit, and disposal. Real 2026 contractor rates per CRCA and NBC 9.23/9.26 guidance.

Estimated deck replacement cost
$9,724
Range: $8,265 – $11,669
deck + tear-off + underlay + repair + add-ons
Decking
$5,830
Tear-off
$2,024
Ice/water shield
$1,440
Synthetic felt
$0
Rafter repair
$0
Fastener upgrade
$0

What this calculator estimates

This calculator quotes the installed 2026 Canadian price for replacing the roof deck (sheathing) layer between the rafters and the shingles, broken out by line item the way Canadian roofers actually invoice:

  • Decking board — 7/16 OSB, 1/2 CSP plywood, T&G planks, or metal pan
  • Tear-off — removing the existing deteriorated deck down to the rafters
  • Ice-and-water shield — self-adhered membrane at eaves and valleys (NBC 9.26.7)
  • Synthetic felt underlayment — full-coverage breathable underlay
  • Rafter sistering — SPF #2 lumber alongside the affected rafter
  • Fastener upgrade — ring-shank nails or screws over smooth-shank
  • Municipal permit, debris removal, and weekend premium

A C$425 minimum service-call floor applies in most Canadian metros — even a small spot repair requires mobilising a two-person crew with extension ladders, harnesses, saws, and a roll-off bin.

How to use it

  1. Enter roof area in square feet. For a typical single-storey Canadian home this is roughly 1.10x to 1.25x the main-floor footprint to account for pitch.
  2. Pick decking substrate — 7/16 OSB for most asphalt-shingle reroofs, 1/2 CSP plywood for coastal humidity or premium upgrades.
  3. Set scope — spot repair (15% of area), partial replace (45%), or full re-deck (100%).
  4. Set storey count — single-storey 1.0x labour, two-storey 1.2x, three-storey 1.45x.
  5. Set access difficulty — easy (drive-up), moderate (rear garden), hard (lift required).
  6. Toggle tear-off to include removal of the existing deck.
  7. Toggle ice-and-water shield — required by NBC 9.26.7 across nearly all of Canada.
  8. Toggle synthetic felt for premium underlay full-coverage outside the ice-shield strip.
  9. Enter rafter sistering feet if any SPF reinforcement is required.
  10. Toggle ring-shank fasteners, municipal permit, debris disposal, weekend premium, and any extra labour hours.

Typical 2026 Canadian deck replacement cost ranges

These ranges reflect 2026 contractor pricing from HomeStars, Renomii, CRCA contractor surveys, and Q1 2026 quotes from major Canadian metros.

Scope (2,000 sq ft area, single-storey, moderate access)2026 installed price
Spot repair 15% (300 sq ft OSB, tear-off, dump)C$1,250 – C$1,800
Partial replace 45% (900 sq ft OSB, tear-off, ice shield, dump)C$4,400 – C$5,900
Full re-deck 100% OSB (with tear-off, ice shield, permit, dump)C$8,900 – C$11,800
Full re-deck 100% CSP plywood (with tear-off, ice shield, permit, dump)C$10,400 – C$13,400
Plank deck (T&G hardwood, premium retrofit)C$14,500 – C$20,000
Rafter sistering (per linear foot)C$17 – C$26
OSB sheet per sheet (4x8, installed)C$80 – C$115
CSP plywood per sheet (4x8, installed)C$100 – C$135

Add 20 percent for two-storey, 45 percent for three-storey. Add 10 to 30 percent for moderate to hard access (no drive-up).

Cost drivers

Existing deck material. Tearing off OSB or plywood is fast. Tearing off Canadian heritage T&G plank decking is slower because each board is hand-nailed individually.

Hidden ice-dam damage. Most deck-replacement quotes include 4 to 8 sheets of substrate replacement in the lump sum. In provinces with severe winters (QC, ON, MB, SK, AB, NB, NS), ice-dam damage at the eaves often extends 1 to 2 m inward from the eaves edge and inflates the per-sheet count.

Pitch and roof geometry. Steep roofs above 8/12 pitch require fall protection and harness work that slows crews by 25 to 40 percent. Cut-up roofs with multiple dormers, valleys, and hip transitions take longer per sq ft.

Time of year. Canadian markets in late October through April charge a 15 to 25 percent winter premium because tear-off windows are short and the deck cannot stay exposed overnight. Avoid the late-spring rush (May to July) — that is when storm-claim work fills the schedule and pricing peaks.

Code upgrades. A deck replacement triggers compliance with NBC 2020 current edition: ice-and-water shield, drip edge, synthetic felt in some jurisdictions, ring-shank fastening in high-wind regions. Allow C$0.40 to C$0.85 per sq ft for the code-upgrade bundle.

Canadian code, standards, and certifications

  • NBC 2020 Subsection 9.23 — Wood-frame construction (rafter and sheathing fastener schedules).
  • NBC 2020 Subsection 9.26.7 — Eaves protection (ice-and-water shield).
  • NBC 2020 Subsection 9.36 — Energy efficiency for housing.
  • CSA A123.21 — Standard test method for the dynamic wind uplift resistance of mechanically attached roofing systems.
  • CSA O121 — Douglas fir plywood.
  • CSA O151 — Canadian softwood plywood (CSP).
  • CSA O325 — Construction sheathing (OSB).
  • CRCA Roofing Specifications Manual — Industry best practice.
  • Provincial OHS regulations (e.g. Ontario O. Reg. 213/91, BC OHS Reg. 11, Quebec CNESST) — Fall protection above 3 m.

Get a CRCA-member contractor for any deck-replacement job — these certifications include workmanship warranties and reduce inspection failures with provincial Building Code authorities.

Diagnostic step-by-step before quoting

  1. Walk the attic with a flashlight on a sunny day. Look for daylight, water stains, mould, and soft sheathing.
  2. Probe suspicious areas with an awl. Sound deck resists; rotted deck pushes through.
  3. Inspect from above at the eaves, valleys, around penetrations (chimney, vents, skylights). Soft underfoot tells you instantly.
  4. Photograph everything before tear-off and once the deck is exposed.
  5. Get two itemised quotes that list area, scope, substrate type, tear-off, underlayment, fastener spec, permit, and disposal as separate line items.

Avoiding scams and overcharging

Door-knocker roofers after windstorms commonly claim catastrophic deck rot to inflate the job. Red flags:

  • “Total deck replacement needed” without a written deck-condition photo report.
  • Pressure to sign before the existing roof is even torn off.
  • Refusal to itemise OSB or plywood sq ft as a separate line item from shingles.
  • No CRCA membership, no manufacturer certification (BP Canada, IKO, GAF Canada), no proof of WSIB / WorkSafeBC / CNESST coverage.
  • Cash-only or wire-transfer demands.

Always insist on a written deck-condition report after tear-off, with photos, before any deck replacement line item is invoiced. A reputable CRCA roofer will price the shingle job, tear off, then walk you through the deck and itemise any sheet replacements at a published per-sheet rate.

Sources: 2026 HomeStars Roof Deck Repair Cost Guide; Renomii 2026 trade pricing data; NBC 2020 Subsection 9.23 / 9.26.7 / 9.36; CSA A123.21 / O121 / O151 / O325; CRCA Roofing Specifications Manual 2023; provincial OHS regulations (O. Reg. 213/91, BC OHS Reg. 11, Quebec CNESST); Insurance Bureau of Canada standard home policy summary 2026.

Frequently asked questions

How much does roof deck replacement cost in Canada in 2026?
Most Canadian homeowners pay C$1.40 to C$4.20 per sq ft for roof deck (sheathing) replacement in 2026, all-in with tear-off, new 7/16 OSB or 1/2 CSP plywood, ice-and-water shield at the eaves and valleys (NBC 9.26.7), ring-shank nails, municipal permit, and dump fees. A 2,000 sq ft full re-deck on a single-storey home with moderate access lands around C$9,000 to C$11,500. Spot repairs for soft sections caught early run C$425 to C$1,650. Source: HomeStars and Renomii 2026 contractor surveys plus Q1 2026 quotes from Toronto, Montréal, Vancouver, Calgary, Ottawa, and Halifax.
When is full replacement needed versus spot repair?
Canadian Roofing Contractors Association (CRCA) member contractors use this rule: if more than 25 percent of the deck shows soft spots, mould blackening, ice-dam water staining, or visible sag, full re-decking is the safer and cheaper-over-time call. Below that threshold, replace only the affected sheets. Always inspect from the attic with a flashlight in addition to walking the deck after tear-off — water damage from ice dams in particular telegraphs from the underside before it shows above. Source: CRCA Roofing Specifications Manual 2023 edition.
OSB versus CSP plywood for re-decking?
Both meet NBC 9.23 for roof sheathing at standard 24-inch on-centre rafter spacing. 7/16-inch OSB is roughly 15 to 20 percent cheaper than 1/2-inch CSP plywood and is the contractor default for asphalt-shingle reroofs in 2026 Canada. Plywood is preferred on the BC coast and Atlantic Canada because it resists edge-swell better than OSB when exposed to driving rain. In Québec and Ontario, OSB dominates the new-build market and is fully accepted for residential reroofs. Source: Canadian Plywood Association (CANPLY) and APA E30 spec sheet.
Is ice-and-water shield required in Canada?
Yes. Under NBC 2020 Subsection 9.26.7, an eaves protection of a self-adhering polymer-modified bitumen membrane or two layers of underlay cemented together is required from the eaves edge to a point not less than 900 mm inside the inner face of the exterior wall in every region of Canada where the January 2.5 percent design temperature is -16 °C or colder — effectively the entire country. Brands routinely specified include Grace Ice & Water Shield, GAF StormGuard, IKO ArmourGuard, and Soprema Sopralast. Allow C$0.65 to C$0.95 per sq ft of covered area.
Do I need to replace the rafters too?
Rafters typically only need work where there is visible sag, broken framing, or rot at the wall-plate seat. The standard repair is sistering: a new SPF (spruce-pine-fir) #2 or better 2x8 or 2x10 alongside the existing rafter, bolted through. Cost in 2026 CAD is C$17 to C$26 per linear foot installed including the lumber, structural-grade bolts, and labour. Full rafter replacement is rare and runs C$32 to C$55 per linear foot. Provincial building codes require structural-engineer sign-off on any rafter work over 6 metres in length.
Will home insurance cover deck replacement?
Canadian home insurance covers deck replacement only when the underlying cause is a covered peril (windstorm, hail, fallen tree, fire). Gradual ice-dam damage that recurred over multiple winters without remediation is excluded under most standard policies. After a storm event, photograph any visible damage from inside the attic and request a written assessment from your roofer naming the storm as the proximate cause before lodging with your insurer. Source: Insurance Bureau of Canada (IBC) standard home policy summary 2026.
Can the new deck go over the old?
No. NBC 2020 Subsection 9.23 and the CRCA Roofing Specifications Manual both require new sheathing to be fastened directly to the rafters or trusses. Layering boards traps moisture and creates a structural risk the inspector will reject. The old deck must come off, the framing must be inspected, then the new sheathing goes down to NBC fastener schedules.
What fasteners are required?
NBC 9.23.3.4 specifies the fastener schedule for roof sheathing. The standard is 51 mm (2 inch) galvanised common nails at 150 mm on-centre at panel edges and 300 mm in the field. In high-wind regions (coastal BC, NB, NS, NL), the schedule tightens to 100 mm on-centre at panel edges with ring-shank or screw fasteners. Ring-shank costs about 15 percent more than smooth-shank but provides 50 percent more withdrawal resistance — recommended everywhere, not just high-wind coastal markets. Allow C$0.14 to C$0.18 per sq ft for the upgrade.

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