Deck cost per square foot
The number you want is installed cost per square foot, and the number you usually get is material cost per square foot. Those differ by a factor of three to four, and the gap is the entire conversation.
Installed cost by material
| Decking | Material per sq ft | Installed per sq ft | 240 sq ft total |
|---|---|---|---|
| Pressure-treated pine | $2.50–4.50 | $15–25 | $3,600–6,000 |
| Cedar | $4.50–7.50 | $20–32 | $4,800–7,700 |
| Composite (capped) | $6–12 | $28–45 | $6,700–10,800 |
| PVC | $9–16 | $32–50 | $7,700–12,000 |
| Hardwood (ipe) | $9–16 | $35–60 | $8,400–14,400 |
These are US figures for 2026 and they move with lumber futures. The ratios are more stable than the absolute numbers: composite is roughly 1.7× treated pine installed, and hardwood is about 2.2×.
What the per-square-foot number usually includes
- Decking, joists, beam, posts and footings.
- Standard railing — often 10–15% of the total, and more if the deck is high.
- Stairs, usually priced per step rather than per square foot.
- Labour, fasteners, and cleanup.
What it usually does not
- Permit and drawings — $150–600.
- Demolition and disposal of an old deck — $1,500–4,000.
- Footings below 4 ft, where frost depth means deeper holes and more concrete.
- Site access — a deck in a back garden with no vehicle access costs more per square foot, sometimes 15–25%.
- Premium railing — cable or glass can add $40–70 per linear foot.
- Skirting, lighting, built-in seating and anything else that is not decking and railing.
Why two quotes for the same deck differ by 100%
Four things explain almost all of it:
- Height. A deck 8 ft up needs longer posts, deeper footings, bracing and fall protection. That can add 30–50% over a ground-level deck of the same area.
- Railing. Railing is priced per linear foot, and a deck with three open sides has 60% more railing than one against two walls. On a small deck, railing can be a third of the total.
- What is excluded. A low quote frequently excludes footings, permit, or railing. Read the scope, not the total.
- Access and staging. Material carried 200 ft through a gate costs more than material dropped at the kerb.
The one number worth calculating yourself
Area is the only figure that scales predictably. Multiply your deck area by the installed range for your material, then add railing at $25–75 per linear foot of open edge, stairs at $150–400 per step, and $1,500–4,000 if there is an old deck to remove. That total will be within 15% of a real quote, which is enough to judge whether a quote is reasonable.
What a per-square-foot number hides
- It does not quote your project. Local labour rates vary by a factor of two across the US.
- It does not account for current lumber prices, which moved 40% within a single year twice in the last decade.
- It does not cover financing or ROI, which is a different kind of question.
- It does not include landscaping or repair of the ground the deck disturbed.
Questions people actually ask
How much does a deck cost per square foot?
Installed, $15–25 per square foot for pressure-treated pine, $28–45 for composite, and $35–60 for hardwood. Material alone is roughly a third of those numbers.
Is it cheaper to build a deck yourself?
Labour is 40–55% of the installed cost, so self-building saves that — but only if the frame and footings are right. The two things a professional adds that are hardest to replicate are the footing depth and the ledger flashing.
Why is my deck quote so much higher than the per-square-foot average?
Usually height, railing length, or site access. A deck 8 feet up with railing on three sides can cost 50% more per square foot than a ground-level deck against two walls.
What is not included in a deck quote?
Often the permit, demolition of the old deck, premium railing upgrades, and skirting or lighting. Read the scope rather than comparing totals.