Cost per square foot, by material and project
| Item | Range | Source |
|---|---|---|
| Full deck build, installed | $30–$60+ per sq ft | Angi (national) |
| Typical deck project | $4,339–$12,652+ (avg $8,320) | Angi (national) |
| Composite decking, installed | $15–$32+ per sq ft | Angi composite guide |
| 360 sq ft composite deck | $5,400–$11,500+ | Angi composite guide |
| Pressure-treated boards (material) | $2–$5+ per sq ft | Angi |
| Cedar boards (material) | $3–$7+ per sq ft | Angi |
| Redwood boards (material) | $5–$35+ per sq ft | Angi |
| Composite boards (material) | $12–$22+ per sq ft | Angi |
| Deck replacement | $4,500–$18,000+ (avg about $8,000) | Angi replacement & repair guide |
| Demolition and haul-off | $5–$15+ per sq ft | Angi |
| Deck repair | about $2,246 on average | Angi |
All figures are national. Bay Area projects typically run higher. Published per-square-foot numbers differ in what they include, so ask each builder whether framing, railings, stairs and permits are in the price.
Get pricing for your deckCommon deck sizes, worked out
| Size | Area | Low ($30/sq ft) | High ($60+/sq ft) |
|---|---|---|---|
| 12 × 12 ft | 144 sq ft | $4,320 | $8,640+ |
| 14 × 20 ft | 280 sq ft | $8,400 | $16,800+ |
| 16 × 20 ft | 320 sq ft | $9,600 | $19,200+ |
| 20 × 20 ft | 400 sq ft | $12,000 | $24,000+ |
The arithmetic is area × rate. The low column fits a simple, low, wood deck on flat ground; the high column is a starting point for composite, raised or hillside decks, not a ceiling. Real quotes can land below or above these numbers.
What moves the price
- Height and slope. Raised and second-story decks need taller posts, bracing, bigger footings and often engineering. Angi keeps a separate second-story deck cost guide because the per-square-foot rate climbs. See hillside decks.
- Decking material. Board prices alone span $2 to $35+ per square foot. Composite and premium redwood cost the most; pressure-treated the least.
- Stairs and railings. Every flight of stairs and every linear foot of guard adds cost. Cable, glass and aluminum systems run above wood rails.
- Demolition. Removing an old deck adds $5–$15+ per square foot for tear-out and disposal (Angi), more if access is tight. See deck replacement.
- Permits and engineering. Most attached or raised decks need a permit, plans and inspections; tall hillside decks may need an engineer. See permits.
- Fire-rated materials. In fire hazard zones, decking within 10 ft of the house may need listed or fire-retardant-treated material. See fire-resistant decking.
- Access. Steep side yards, long carries and no room for equipment slow every step of the job.
Does a deck pay back at resale?
Nationally, the 2025 Cost vs Value report puts a composite deck addition at $25,096 with about 89% recouped at sale, and a wood deck addition at $18,263 with about 95% recouped. These are national averages for a mid-range 16×20 project, not appraisals for a Walnut Creek home.
How to compare deck bids
- Same scope on every bid: size, height, stairs, railing type and length.
- Footing plan and post size named, especially on a slope.
- Framing lumber grade and joist spacing, plus how the ledger is attached and flashed.
- Exact decking product and fastener system (face screws or hidden clips).
- Demolition, haul-off and site protection included or excluded.
- Who pulls the permit, and whether plan or engineering fees are in the price.
- Payment schedule tied to completed work, with the down payment within the legal limit.
More on vetting builders in choosing a deck builder.
Deck cost questions
How much does a 12×12 deck cost?
A 12×12 deck is 144 square feet. At $30–$60+ per square foot (Angi national range) that works out to about $4,320–$8,640+. A low wood deck with no stairs sits near the bottom; composite, a raised deck or difficult access moves it up.
How much does a 14×20 deck cost?
A 14×20 deck is 280 square feet: about $8,400–$16,800+ at $30–$60+ per square foot. Replacing an existing 14×20 deck adds demolition and haul-off, which Angi puts at $5–$15+ per square foot.
How much does a 20×20 deck cost?
A 20×20 deck is 400 square feet: about $12,000–$24,000+ at the national rate. Bay Area labor, stairs, second-story height and premium decking can take it well beyond that.
Is composite more expensive than wood?
Yes, up front. Angi lists composite decking materials at $12–$22+ per square foot versus $2–$5+ for pressure-treated and $3–$7+ for cedar, while redwood ranges from $5 to $35+ depending on grade. Composite saves on staining and sealing over the years.
Does a new deck add value?
The 2025 Cost vs Value report puts a national composite deck addition at $25,096 with about 89% of the cost recouped at sale, and a wood deck addition at $18,263 with about 95% recouped. Local results vary.