Cost to Build a Deck in Seattle, WA (2026)
In Seattle a 12×16 ft deck costs about $4,903 in pressure-treated pine and $10,299 in composite, installed — 13% above the US average. Below: local prices by size, footing depth, permits and a calculator priced for Seattle.
Pressure-treated pine
$23–$30 /sq ft
Cedar
$31–$40 /sq ft
Composite
$48–$62 /sq ft
Deck cost calculator for Seattle
Priced with Seattle labour, material and footing-depth factors. Change any input and the estimate updates.
Estimated installed cost
$9,063 – $11,843
192 sq ft · about $53.64/sq ft
- Materials
- $6,457
- Labour
- $3,842
- Footings (12 in deep)
- 3 × about $128
- Frost-depth adjustment
- −$115
Mid-range estimate for a rectangular deck attached to the house, with one beam line per 12 ft of depth and footings every 8 ft. Excludes demolition, permits and site work. For railing, stairs and a full line-item breakdown use the main deck cost calculator.
Seattle deck cost by size and material
Mid-range installed prices for a standard-height deck attached to the house, with footings at 12 inches. Add railing and stairs in the deck cost calculator.
| Deck size | Pressure-treated pine | Cedar | Composite |
|---|---|---|---|
| 10 × 10 ft (100 sq ft) | $2,499 | $3,366 | $5,309 |
| 12 × 12 ft (144 sq ft) | $3,649 | $4,898 | $7,695 |
| 12 × 16 ft (192 sq ft) | $4,903 | $6,569 | $10,299 |
| 16 × 20 ft (320 sq ft) | $8,057 | $10,833 | $17,049 |
| 20 × 20 ft (400 sq ft) | $10,148 | $13,618 | $21,388 |
What makes a deck in Seattle cost what it does
Long wet winters grow moss and algae; steep lots mean many elevated decks.
Labour here runs 10% above the Washington average, so a pressure-treated 12×16 that averages $4,706 across Washington comes to about $4,903 in Seattle. Wet, mild winters west of the Cascades grow moss and algae on wood; the east side is dry with cold winters.
Footings
Footings in Seattle go about 12 inches deep, which costs roughly $128 per 12 inch footing installed. A 12×16 deck needs about 3. Size them with the deck footing calculator.
Deck permits in Seattle
Permits are issued by the Seattle Department of Construction & Inspections (SDCI). SDCI permits decks over 30 inches or attached to the house; steep-slope and landslide-prone areas need extra geotechnical review. Typical fees run $300–$900. For the state rules that sit behind the local ones, see deck cost in Washington.
Choosing decking in Seattle
Composite adds about $5,395 to a 12×16 deck here over pressure-treated. Western red cedar is produced in-state, so it is cheaper here than almost anywhere else. Run the numbers for your deck in the composite vs wood calculator.
Best time to build
June to September west of the Cascades.
Frequently asked questions
How much does a deck cost in Seattle?
A 12×16 ft deck in Seattle costs about $4,903 in pressure-treated pine, $6,569 in cedar and $10,299 in composite, installed. That is $23–$30 per square foot for pressure-treated and $48–$62 for composite.
Is building a deck in Seattle more expensive than elsewhere in Washington?
A typical deck in Seattle runs 3% above the Washington average and 13% above the US average, mainly because of local labour rates. Long wet winters grow moss and algae; steep lots mean many elevated decks.
Do I need a permit for a deck in Seattle?
Permits are issued by the Seattle Department of Construction & Inspections (SDCI). SDCI permits decks over 30 inches or attached to the house; steep-slope and landslide-prone areas need extra geotechnical review. Budget roughly $300–$900 for the permit, more if drawings by a design professional are required.
How deep do deck footings have to be in Seattle?
About 12 inches. Each 12 inch footing at that depth costs roughly $128 installed, and a 12×16 deck needs about 3. Always confirm the required depth with the Seattle Department of Construction & Inspections (SDCI) before digging — the footing inspection happens before any concrete goes in.
Should I choose composite or wood for a deck in Seattle?
Composite adds about $5,395 to a 12×16 deck in Seattle but removes staining every two to three years. Western red cedar is produced in-state, so it is cheaper here than almost anywhere else.
Price the rest of the project
Figures are planning estimates built from national installed prices adjusted for Washington and Seattle labour, materials and footing depth. Get two or three itemised local quotes. Method.