A deck is one of the few renovations you can price with reasonable confidence before calling anyone: it is mostly lumber, fasteners and labour, with the material choice doing most of the work on the final number. In Ontario in 2026, a typical 300 sq ft deck runs roughly $8,000–$18,000 in pressure-treated wood or $18,000–$35,000+ in composite.
Figures below are NorthPeak planning estimates for contractor-built decks, including footings, framing, decking, railings and stairs. DIY cuts labour (roughly 40–50% of the total) but not material costs.
Material costs: the decision that sets the budget
| Material | Per sq ft installed | 300 sq ft deck | Lifespan |
|---|---|---|---|
| Pressure-treated pine | $27–$60 | $8,000–$18,000 | 15–20 years with maintenance |
| Cedar | $47–$83 | $14,000–$25,000 | 20–25 years |
| Composite | $60–$117+ | $18,000–$35,000+ | 25–30+ years, minimal upkeep |
Composite costs more upfront but needs no staining or sealing — over 20 years the maintenance savings narrow the gap considerably.
The add-ons that surprise people
- Railings ($40–$80 per linear foot installed): code requires guards on decks over 24 inches high; glass or cable railings cost far more than wood.
- Stairs ($1,500–$4,000): each staircase is essentially custom carpentry.
- Footings ($200–$400 each): Ontario frost depth means footings 4 feet deep; a 300 sq ft deck needs 6–10.
- Permits ($200–$600): most Ontario municipalities require a building permit for decks over about 108 sq ft (10 m²) or attached to the house — check your local by-law.
- Lighting and skirting ($500–$2,500): the finishing touches that make a deck look built-in rather than bolted-on.
The permit line
Rules vary by municipality, but the common Ontario thresholds are: a permit is required if the deck is attached to the house, more than 24 inches above grade, or larger than about 108 sq ft. Floating ground-level decks under those limits often skip permits — but railings, stairs and setback rules still apply. Call your municipal building department before buying lumber; a stop-work order costs more than the permit.
Composite vs. wood, honestly: composite wins on lifetime cost if you will own the home 15+ years and hate staining. Pressure-treated wins on upfront budget and is easier to repair board-by-board.
Frequently asked questions
How much does a deck cost in Ontario in 2026?
A 300 sq ft deck costs roughly $8,000–$18,000 in pressure-treated wood, $14,000–$25,000 in cedar, or $18,000–$35,000+ in composite, installed. Railings, stairs and permits add $2,000–$8,000.
Is composite decking worth the extra cost?
Over 20+ years, often yes — no staining, sealing or board replacement. Upfront it costs roughly double pressure-treated. For shorter ownership horizons, wood usually wins on value.
Do I need a permit for a deck in Ontario?
Usually yes if it is attached to the house, over 24 inches high, or larger than about 108 sq ft. Ground-level floating decks under local thresholds often do not — confirm with your municipality.
How long does it take to build a deck?
A contractor crew typically builds a standard deck in 1–2 weeks; permits can add 2–6 weeks before work starts. DIY builds often take 3–4 weekends.
Sources and methodology
- Vista Builders: Home Renovation Cost in Ontario (2026 Guide)
- Canada Mortgage and Housing Corporation (CMHC)
- HomeStars
This article provides general information for planning purposes, not professional advice or a quote. Cost figures are NorthPeak planning estimates unless a source is named; confirm current prices with licensed local contractors and professionals before making decisions.