Cost to Composite Deck Building in Seattle, WA (2026)
If you’re budgeting a composite deck building in Seattle, most projects run $10,738-$26,248, 19% above the $14,000 national average. What moves that number most is usually one thing: Deck Size. On its own it can swing the cost by $3,000 - $15,000+, so that’s the decision to slow down on before you sweat the smaller stuff.
Easiest place to save: Choose entry-level composite over premium lines. Trex Enhance or Fiberon Basics deliver solid performance at $5-$7/sq ft vs. $10-$14 for premium boards - saving $1,500-$2,100 on a 300 sq ft deck.
In the West Coast (where Seattle sits): Highest labor costs, strict permitting and inspection requirements.
$10,738-$26,248 in Seattle
19% above the national average · 1.19x cost multiplier
In Seattle, a composite deck building runs $10,738 to $26,248 on average - about 19% above what homeowners pay nationwide. The West Coast market's labor costs account for most of the gap, with material pricing and local permitting fees adding to the spread. Use the cost table below to compare budget, mid-range, and premium options side by side.
Cost Breakdown in Seattle
| Line Item | Low | Mid | High |
|---|---|---|---|
| Cost per sq ft | $48 | $66 | $95 |
| Materials | $5,130 | $8,550 | $15,960 |
| Labor | $5,039 | $9,448 | $15,117 |
| Permits | $285 | $399 | $570 |
| Total | $10,454+16% vs. national avg | $19,138+20% vs. national avg | $33,357+19% vs. national avg |
Budget
Entry-level composite (Trex Enhance or Fiberon), ground-level, basic railing, simple rectangular layout, $30-$45/sq ft for 300 sq ft
Mid-Range
Mid-tier composite (Trex Select or TimberTech), standard height, upgraded railing system, $45-$65/sq ft for 300 sq ft
Premium
Premium composite (Trex Transcend or Azek), multi-level or elevated, aluminum railing, built-in lighting, $65-$100+/sq ft for 300 sq ft
Material Options
Material prices below are national averages; availability in Seattle may shift costs slightly.
| Material | Cost/Unit | Best For |
|---|---|---|
| Trex Enhance | $5-$7/sq ft (material) | Budget-conscious builds where composite is preferred over woodMost affordable Trex line, good color selection, 25-year warranty |
| Trex Select | $7-$9/sq ft (material) | Most popular mid-range choice, good balance of price and performanceBetter fade and stain resistance, more natural wood grain, 25-year warranty |
| Trex Transcend | $10-$14/sq ft (material) | Premium builds where appearance is a priorityBest Trex aesthetics, deep wood grain, superior scratch resistance, 25-year warranty |
| TimberTech / Azek | $7-$12/sq ft (material) | Homeowners wanting maximum longevity and minimal maintenanceCapped polymer (Azek) is virtually maintenance-free, excellent color retention, 30-50 year warranties |
| Fiberon | $5.50-$9/sq ft (material) | Value-oriented builds, comparable quality to Trex at a lower priceCompetitive pricing, solid warranty, good color options |
Other Projects in Seattle
Seattle Estimate
Typical Range
$10,738-$26,248
vs. National Average
19% above national
Cost Multiplier
1.19x
Cost Per sq ft
$48-$95
This 1.19x estimate prices Seattle labor from BLS Occupational Employment and Wage Statistics (May 2025) and applies a lighter regional adjustment to materials and permits, which vary less by metro than labor does. Actual bids vary by contractor, project scope, and timing.
See national average costs →