Cost to Build a Deck in Washington (2026)
A 12×16 ft deck in Washington runs about $4,706 in pressure-treated pine and $9,958 in composite, installed — 8% above the US average. Here is what moves that number in Washington, with a calculator priced for the state.
Pressure-treated pine
$22–$28 /sq ft
Cedar
$29–$38 /sq ft
Composite
$46–$60 /sq ft
Deck cost calculator for Washington
Priced with Washington labour, material and footing-depth factors. Change any input and the estimate updates.
Estimated installed cost
$8,763 – $11,451
192 sq ft · about $51.86/sq ft
- Materials
- $6,192
- Labour
- $3,766
- Footings (21 in deep)
- 3 × about $157
- Frost-depth adjustment
- −$29
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.
Washington deck cost by size and material
Mid-range installed prices for a standard-height deck attached to the house, including framing, footings at the local depth and hardware. Railing and stairs are priced separately in the main deck cost calculator.
| Deck size | Pressure-treated pine | Cedar | Composite |
|---|---|---|---|
| 10 × 10 ft (100 sq ft) | $2,437 | $3,277 | $5,172 |
| 12 × 12 ft (144 sq ft) | $3,523 | $4,731 | $7,461 |
| 12 × 16 ft (192 sq ft) | $4,706 | $6,318 | $9,958 |
| 16 × 20 ft (320 sq ft) | $7,815 | $10,501 | $16,567 |
| 20 × 20 ft (400 sq ft) | $9,788 | $13,146 | $20,728 |
What drives deck prices in Washington
Labour
Labour is the biggest regional variable. Carpentry labour in Washington runs 22% above the national level, so a composite 12×16 that averages $9,216 nationally comes to about $9,958 here. On pressure-treated decks labour is more than half the bill, so the regional gap is widest on the cheapest material.
Climate
Wet, mild winters west of the Cascades grow moss and algae on wood; the east side is dry with cold winters.
Footings and frost depth
Footings in Washington typically go 12–30 inches deep. At 21 inches each 12 inch footing costs roughly $157 installed, and a 12×16 deck needs about 3 of them — a saving of $29 against the 24 inch depth national prices assume.
Which decking makes sense here
Our pick for most Washington homes: cedar. Western red cedar is produced in-state, so it is cheaper here than almost anywhere else. Composite adds about $5,251 to a 12×16 deck over pressure-treated — see the full 20-year comparison in the composite vs wood calculator.
Permits and code in Washington
The Washington State Residential Code applies statewide; Seattle and King County permit attached and elevated decks. Footings are about 12 inches west and up to 30 inches east.
Typical deck permit fees: $200–$700. Expect a footing inspection before concrete, a framing inspection before the decking goes down and a final. Estimate your fee with the deck permit cost calculator, and read our deck permit guide for what the drawings need to show.
Best time to build a deck in Washington
June to September west of the Cascades.
Deck cost in Washington cities
- Seattle — 12×16 composite about $10,299
Compare neighbouring states
Frequently asked questions
How much does it cost to build a deck in Washington?
A typical 12×16 ft (192 sq ft) deck in Washington costs about $4,706 installed in pressure-treated pine, $6,318 in cedar and $9,958 in composite. That is $22–$28 per square foot for pressure-treated and $46–$60 for composite — 8% above the US average.
Is a composite deck worth it in Washington?
On a 12×16 deck composite costs about $5,251 more than pressure-treated up front. Western red cedar is produced in-state, so it is cheaper here than almost anywhere else. Composite needs no staining, which saves a refinishing cycle every two to three years on wood.
Do I need a permit to build a deck in Washington?
The Washington State Residential Code applies statewide; Seattle and King County permit attached and elevated decks. Footings are about 12 inches west and up to 30 inches east. Where a permit is required, fees typically run $200–$700. Under the model residential code, a freestanding deck under 200 sq ft and no more than 30 inches above grade that does not serve an exit door is often exempt — attaching it to the house removes that exemption.
How deep do deck footings need to be in Washington?
Typically 12 to 30 inches depending on the part of the state. At about 21 inches, each 12 inch footing costs roughly $157 installed, compared with $167 at a 24 inch depth. Confirm the exact depth with your building department before digging.
When is the best time to build a deck in Washington?
June to September west of the Cascades. Booking a builder outside the spring rush often gets a faster start date and a keener price.
Is Washington expensive for deck building compared with other states?
Washington ranks 41 of 50 from cheapest to most expensive on our index. Carpentry labour runs 22% above the national level and materials right in line with it, which puts a typical deck 8% above the US average.
Price the rest of the project
How these figures are made: national installed prices per square foot, split into materials and labour and adjusted by a Washington labour index (reasoned from BLS state carpenter wage data), a material and freight index, and the local footing depth. They are planning estimates — get two or three itemised local quotes. Method.