How Much Does a Deck Cost in Seattle, WA? (2026 Pricing Guide)

Quick Answer

Deck installation costs in the Seattle, WA area range from $5,400 for a basic 300 sq ft pressure-treated deck to $65,000 for a large composite deck. The 2026 average for a mid-range 300-sq-ft cedar or composite deck is $12,500 to $20,000, with permits adding 5–10% on top.

These are real labor + materials prices for King, Snohomish, Pierce, and Kitsap counties, including ground prep, footings, framing, decking, railings (required at 30+ inches per WA code), and stairs.

Cost by Material (Per 300 sq ft Deck)

The single biggest variable in deck cost is the decking material:

Material300 sq ft costLifespanMaintenancePressure-treated (PT) lumber$5,400–$9,00015–20 yearsAnnual stain/sealCedar$7,500–$12,00020–25 yearsStain every 2–3 yearsComposite (Trex, TimberTech)$10,500–$19,50025–30 yearsWash only

For larger decks (500+ sq ft), composite decking pricing scales linearly:

• Mid-range composite (Trex, TimberTech, Fiberon) — $28,000 to $65,000 for 300–500 sq ft
• Cedar — $12,500 to $20,000 for similar footprints
• Premium PVC capped composite (Azek, TimberTech AZEK) — 15–25% above standard composite

Why Composite Dominates Seattle Decks

Pacific Northwest weather is hostile to wood. Heavy rain from October through May, combined with high humidity, accelerates rot, mildew, and fastener corrosion. Most Seattle homeowners going through a full deck rebuild now choose composite decking despite the higher upfront cost because:

• Zero rot risk (synthetic core)
• No annual staining required (saves $400–$1,200/year in maintenance)
• 25–30 year warranty from major brands
• Resists moss and mildew that plague cedar decks in shady Seattle yards
• ROI at resale tracks closer to investment than wood does

Cedar still has aesthetic and environmental appeal — it's the right choice for Craftsman bungalow style and tight-budget projects. Pressure-treated lumber is the budget option but plan for a full rebuild in 15–20 years.

Cost Per Square Foot — Installed (2026 Seattle)

Decking typePer sq ft installedPressure-treated$18–$30Cedar$25–$40Composite (mid-range)$35–$65Composite (premium)$55–$90Hardwood (ipe, mahogany)$70–$120

Above prices include framing, posts, footings, decking, hardware, and standard railing. They do NOT include extras like built-in benches, planters, lighting, pergolas, or hot tub support framing.

Deck Resurfacing — A Cost-Effective Alternative

If your deck framing is structurally sound but the deck boards are aging, resurfacing rebuilds only the visible deck surface and railings while keeping the existing posts and joists:

• Resurface with composite — $10,000+ for a 300-sq-ft deck
• Resurface with cedar — $6,500–$10,000
• Resurface with PT lumber — $3,500–$6,000

This is a realistic option for decks where the structure has 10+ years of life left. We inspect every joist and post during demo — if rot is found, the project converts to a full rebuild. About 30–40% of resurface inquiries in Seattle end up as full rebuilds because hidden rot is discovered.

What Drives Deck Costs in Seattle

1. Deck height. Decks under 30" off the ground need only basic safety — under-30 decks save $1,500–$3,500 vs raised decks. Washington state code requires railings on any deck 30 inches or higher, which adds significant material and labor.

2. Footings. Standard concrete pier footings for a 300-sq-ft deck run $1,200–$2,000. If your soil is rocky or has water issues (common in Seattle hillside lots), helical piers or deeper footings can add $2,000–$5,000.

3. Stairs. Each set of deck stairs adds $1,500–$3,500 depending on rise/run and material. Many Seattle hillside properties (Queen Anne, Magnolia, Kirkland) need multi-level stairs — significant cost driver.

4. Railings. Code-compliant railings cost $50–$120 per linear foot installed. Premium options (steel cable, glass panels) run $150–$300+/lf. A typical 300-sq-ft deck needs 60–80 linear feet of railing.

5. Permits. Required in every Seattle metro city for any deck attached to a house. Permit fees run 5–10% of total project cost and add 2–4 weeks for plan review.

Permit Requirements — Seattle Metro

Washington state and Seattle area cities require deck permits for:

• Any deck attached to a house (including resurfaces if structural changes)
• Any deck 30 inches or more above grade
• Any deck over 200 sq ft (regardless of height)
• Any deck supporting a hot tub or roof structure

City of Seattle (SDCI): $400–$900 base permit, plus structural plan review for raised decks.

King County (unincorporated): $300–$700 base.

Bellevue: $500–$1,200 — plan review can take 4–6 weeks.

Tacoma / Pierce County: $250–$600.

In hillside neighborhoods (Magnolia, West Seattle, Queen Anne, Issaquah), expect additional structural review for soils and slope.

Deck Cost by City (Seattle Metro)

Labor and material costs vary across the metro:

AreaMid-range cedar (300 sq ft)Mid-range composite (300 sq ft)Seattle (Ballard, Capitol Hill, West Seattle)$13K–$18K$14K–$20KBellevue / Mercer Island$14K–$20K$16K–$22KKirkland / Redmond / Sammamish$13K–$18K$15K–$21KTacoma / Lakewood$11K–$16K$13K–$18KEverett / Lynnwood / Bothell$12K–$17K$14K–$19KRenton / Kent / Federal Way$11K–$16K$13K–$18K

Eastside cities (Bellevue, Sammamish, Mercer Island) command higher labor rates because of higher home values and stricter permit review.

Deck Cost ROI in Seattle

The 2025 Cost vs Value Report (Pacific region) shows wood deck additions return roughly 70–80% of project cost at resale. Composite decks return slightly less in raw percentage but provide longer functional life. In Seattle's strong housing market, decks frequently appraise at full project cost or above, especially in homes with view potential.

Frequently Asked Questions

How much does it cost to build a deck in Seattle?A 300-square-foot deck in Seattle costs $5,400 to $19,500 depending on material — pressure-treated lumber on the low end, premium composite on the high end. Mid-range composite is the most popular choice at $12,500–$20,000.

Do I need a permit to build a deck in Washington state?Yes — Washington state and Seattle area cities require permits for any deck attached to a house, any deck 30 inches or more above grade, and any deck over 200 sq ft. Permit fees run 5–10% of total project cost.

Why are deck railings required in Washington?Washington state code (and IRC code adopted by Seattle and most metro cities) requires guardrails on any deck surface 30 inches or more above grade. Railings must be at least 36 inches high (42 inches in some commercial applications) with balusters spaced no more than 4 inches apart.

What's the cheapest deck material in Seattle?Pressure-treated lumber is the cheapest at $18–$30 per sq ft installed — about $5,400–$9,000 for a 300-sq-ft deck. The trade-off is a 15–20 year lifespan plus annual staining maintenance.

Is composite decking worth it in Seattle?For most Seattle homeowners, yes. Composite costs 30–60% more upfront but eliminates annual staining, resists rot and mold (huge issue in PNW climate), and lasts 25–30 years. Total cost over 25 years (including maintenance savings) is usually lower than wood.

Can I resurface my old deck instead of rebuilding?If the structural framing (joists, beams, posts) is sound, resurfacing replaces only the deck boards and railings. Cost is $3,500–$10,000+ depending on material — about 50% of a full rebuild. We inspect every component during demo; if rot is found, it converts to a full rebuild.

How long does it take to build a deck in Seattle?A typical 300-sq-ft deck takes 1–2 weeks of construction once permits issue. Plan another 2–4 weeks for permit review beforehand. Total project from contract to completion: 4–6 weeks.

Do I need stairs on my deck?Building code requires at least one means of egress (stairs or door access) from any deck. If your deck is attached to the house and accessible from inside, you may not need exterior stairs — but most homeowners want them for backyard access.

Get a Free Deck Estimate

TopVolk Construction has built decks across Seattle metro since 2017 — from compact Capitol Hill backyard decks to multi-level Sammamish view decks. We provide written estimates with material options, plus permit handling. No pressure.

Call (206) 591-1096 or use the contact form to schedule a free in-home estimate.