Composite Deck costs $45.70 to $97.12 per sq ft in Seattle in 2026. For a 400 sq ft project, expect $18,281 – $38,846 installed, typically near $28,563. That is about 3% above the Washington average.
Seattle composite deck calculator
Planning estimate. Wage index applies to the labor share only; materials held at national prices. Get three written quotes.
Why Seattle runs above the Washington average
Construction wages in Seattle average $42.11 per hour against $39.60 statewide, so labor-heavy work prices above the Washington norm here.
Labor is about 42% of the installed cost on this type of work, and it is the part that actually moves between markets. Materials are priced by national manufacturers and barely shift, which is why the gap between metros is narrower than wage differences alone suggest.
Composite Deck cost by project size in Seattle
| Project size | Seattle range | Typical |
|---|---|---|
| 100 sq ft | $4,570 – $9,712 | $7,141 |
| 200 sq ft | $9,140 – $19,423 | $14,282 |
| 300 sq ft | $13,710 – $29,135 | $21,423 |
| 400 sq ft | $18,281 – $38,846 | $28,563 |
| 600 sq ft | $27,421 – $58,270 | $42,845 |
| 800 sq ft | $36,561 – $77,693 | $57,127 |
| 1,000 sq ft | $45,702 – $97,116 | $71,409 |
| 1,500 sq ft | $68,552 – $145,674 | $107,113 |
Where the money goes
For a 400 sq ft project in Seattle at roughly $28,563, a typical bill splits like this:
| Line item | Share | Cost |
|---|---|---|
| Labor | 42% | $11,997 |
| Materials | 44% | $12,568 |
| Site prep & equipment | 8% | $2,285 |
| Overhead, disposal & finishing | 6% | $1,714 |
Seattle compared with other Washington markets
| Area | Cost per sq ft | vs Seattle |
|---|---|---|
| Spokane | $41.64 – $88.48 | −9% |
| Kennewick | $44.54 – $94.64 | −3% |
| Bremerton | $43.63 – $92.71 | −5% |
| Bellingham | $44.24 – $94.01 | −3% |
| Washington average | $44.37 – $94.28 | −3% |
Ground conditions and code in Seattle
Permits in Seattle
A residential permit for this work typically runs around $700 in Washington. Permit cost is rarely included in a contractor quote, so budget it separately and confirm scope with the Seattle building department before work begins.
Hiring in Seattle
Get three written, itemised quotes from licensed and insured contractors, each specifying the same scope and grade of material. Ask for local references and check the licence is current in Washington.
Frequently asked questions
How much does composite deck cost in Seattle?
In 2026, composite deck costs $45.70 to $97.12 per sq ft in Seattle. For a 400 sq ft project, the installed total typically lands between $18,281 and $38,846.
Is Seattle more expensive than the rest of Washington?
Yes. Seattle runs about 3% above the Washington average, because local construction wages ($42.11/hr) sit above the statewide figure of $39.60/hr.
Do I need a permit in Seattle?
Most work of this type and value requires a permit. Budget around $700 in Washington and allow extra time for review in metro jurisdictions.
How do I compare quotes in Seattle?
Get three written, itemised quotes covering identical scope and materials. A bid far below the others usually signals a reduced specification rather than better value.
Nearby markets
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