12 x 16 (192 sq ft)
Pressure-treated roughly $4,800 – $11,500. Cedar roughly $7,700 – $17,300. Composite roughly $8,600 – $15,400.
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1. What are you planning?
2. Which decking material?
3. Roughly how big, in square feet?
sq ft
4. Railing type
5. Stairs
Installed cost per square foot
The material decision sets the base rate. Everything else is an adjustment on top of it.
Pressure-Treated
$25 – $60 / sq ft
- Lowest entry cost
- Repairable one board at a time
- Needs re-staining every 2-3 years
- Most forgiving material to modify later
Most popular
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Western Red Cedar
$40 – $90 / sq ft
- Naturally rot resistant
- Stays cooler underfoot in sun
- Can be sanded and recoated for decades
- Wants a fresh coat every 2-3 years
Composite
$45 – $80 / sq ft
- No staining cycle at all
- PVC is a step up again at $60 to $100 / sq ft
- Gets hot in direct sun
- Cannot be sanded back if scratched
Typical project totals by size
Published market ranges for a complete build including material and labour. Figures are rounded and assume standard railing and one set of steps.
14 x 20 (280 sq ft)
Pressure-treated roughly $7,000 – $16,800. Cedar roughly $11,200 – $25,200. Composite roughly $12,600 – $22,400.
20 x 20 (400 sq ft)
Pressure-treated roughly $10,000 – $24,000. Cedar roughly $16,000 – $36,000. Composite roughly $18,000 – $32,000.
Resurfacing over sound framing
Roughly $5,000 – $15,000, depending on size, material and whether the railing is replaced at the same time.
Full tear-down and rebuild
Roughly $15,000 – $50,000 depending on size and material, including removal and disposal of the existing deck.
The three add-ons that move the number most
Square footage sets the base. These three decide where in the range you land.
Railing
Roughly $25 to $250 per linear foot. On a mid-sized deck the gap between wood picket and glass panel is a bigger swing than the decking material.
Stairs
Roughly $500 to $1,500 all-in per run beyond the first set, and more where the grade forces an intermediate landing.
Permit
Published figures for an Ottawa residential deck permit generally fall in the $200 to $500 range, above a minimum fee, once the deck clears 600 mm above adjacent grade.
Questions about deck pricing
Why is there such a wide range on these figures?
Ottawa builders publish figures that disagree with each other by a factor of three. On pressure-treated alone, published Ottawa rates run from about $20 per square foot at one company to about $90 at another, and two Ottawa builders publish whole-project positions that do not overlap at all. Brand, board grade, site access, height and whether the frame needs work all account for part of the gap, and marketing positioning accounts for the rest. We publish the spread and name the disagreement rather than pretending there is one market rate.
Is the calculator result a quote?
No, and it cannot be. It has no way of knowing how far your footings have to go before they hit stable ground, whether material can get to the back of the house without being carried by hand, or whether your rear wall can take a ledger connection at all. It is a planning range to tell you whether the project is in the right neighbourhood for your budget.
Does the estimate include the permit and drawings?
No. The ranges cover the build itself, material and labour. Permit fees are paid to the City and drawings are quoted separately, because both depend on the deck's height above grade and whether an engineered detail is needed.
Why is a small deck not proportionally cheaper?
Because a chunk of the cost does not scale with area. Mobilising to site, digging and pouring footings, and the ledger connection to the house all cost close to the same on a 120 square foot deck as on a 200 square foot one. Small decks carry a higher effective rate per square foot, which is why the calculator starts at 80 square feet.