Deck cost in Seattle (2026):
prices, when you need a permit and the City rules
HOW MUCH DOES A DECK COST IN SEATTLE?
Angi puts building a deck in Seattle at $5,272 to $14,994, with an average of $10,133, or about $37 to $74 per square foot. The City of Seattle requires a permit for a deck more than 18 inches above the ground, a roof deck or a deck in an environmentally critical area. Sales tax of 10.55% applies to the whole contract.
Deck cost in Seattle
| Seattle (Angi) | Reported cost |
|---|---|
| Typical range | $5,272–$14,994 |
| Average | $10,133 |
| Per square foot | $37–$74 |
| Floating (ground-level) deck | $25–$74 per sq ft |
| Framing labor | $11–$15 per sq ft |
| Decking materials | from $2.50 (pressure-treated) to $25 (aluminum) per sq ft |
Example: what a deck could cost
| Deck size | At $37–$74 per sq ft | With 10.55% sales tax |
|---|---|---|
| 12×12 ft (144 sq ft) | $5,328–$10,656 | $5,890–$11,780 |
| 12×16 ft (192 sq ft) | $7,104–$14,208 | $7,853–$15,707 |
| 16×20 ft (320 sq ft) | $11,840–$23,680 | $13,089–$26,178 |
Washington taxes construction for a homeowner on the whole contract, labor included: see sales tax on home repairs.
Do you need a permit for a deck in Seattle?
| Deck | Permit (SDCI) |
|---|---|
| 18 inches or less above the ground, not in a critical area | Not required |
| More than 18 inches above the ground | Subject-to-field-inspection construction permit |
| More than 8 feet high, beams 14 feet or longer, solid flooring, or over 750 sq ft | Addition/alteration construction permit |
| Roof deck, or in an environmentally critical area (ECA) | Addition/alteration construction permit; ECA sites need a pre-application site visit |
- Drawings: SDCI says deck drawings rarely need an architect's or engineer's stamp; anyone with drafting skills can prepare them.
- Fees: SDCI sets fees from the value of the work, using its Fee Estimator. For a subject-to-field-inspection permit, you pay 40% of the calculated plan review fee. SDCI's 2026 base hourly rate is $292.
- Ledger: if the deck is supported by a ledger at the house, it must be anchored so it won't pull away in an earthquake, using the Seattle Residential Code connection (R507.9.1.3) or an engineer's design.
Setbacks, lot coverage and safety rules
- Setbacks (decks over 18 inches high): 10 to 15 feet from the front lot line; 3 to 5 feet from each side lot line in neighborhood residential zones; 5, 10 or 15 feet from the rear lot line, depending on the number of units.
- Lot coverage: decks more than 36 inches above the ground count toward lot coverage, capped at 50% of the lot in NR1, NR2 and NR3 zones.
- Guardrails: required more than 30 inches above the surface below; at least 36 inches tall, with openings under 4 inches.
- Stairs: risers up to 7-3/4 inches, treads at least 10 inches, width at least 36 inches; a handrail is needed with four or more risers.
- Load: SDCI requires design for at least 60 pounds per square foot.
Fences: different rules
- SDCI says a fence up to 8 feet high doesn't need a permit, unless it has masonry or concrete parts over 6 feet or is in a flood-prone area.
- In neighborhood residential and multifamily zones, the base height limit is 6 feet, and 4 feet in a front or street-side setback.
- A fence on a retaining wall that raises the grade is limited to 9 feet 6 inches combined.
- Prices by material and length: fence cost in Seattle.
Before you sign
- Ask who prepares the drawings and applies for the SDCI permit, and whether the fee is in the quote.
- Get the size, height, materials and ledger connection in writing.
- Check the contractor on L&I's Verify a Contractor tool, and get the disclosure statement for jobs of $1,000 or more: see construction liens and contractor bond claims.
- Planning a larger addition? Its added value may qualify for the home improvement property tax exemption if you file before the work is finished.
Frequently asked questions
How much does a deck cost in Seattle?
Angi puts a new deck in Seattle at $5,272 to $14,994, with an average of $10,133, or about $37 to $74 per square foot. Sales tax of 10.55% and the SDCI permit come on top.
Do I need a permit to build a deck in Seattle?
Yes, if the deck is more than 18 inches above the ground, is a roof deck or is in an environmentally critical area. Most decks need a subject-to-field-inspection construction permit from SDCI.
How close to the property line can I build a deck in Seattle?
For decks more than 18 inches high, SDCI lists 10 to 15 feet from the front lot line, 3 to 5 feet from side lot lines in neighborhood residential zones, and 5 to 15 feet from the rear lot line, depending on the number of units.
When does a deck need a guardrail in Seattle?
When it is more than 30 inches above the surface below. The guardrail must be at least 36 inches tall, with openings smaller than 4 inches.
Do I need a permit for a fence in Seattle?
Not for a fence up to 8 feet high, unless it has masonry or concrete parts over 6 feet or is in a flood-prone area. Height limits still apply: 6 feet in most residential areas and 4 feet in front setbacks.
Other outdoor work: exterior and yard cost guides.
About these prices. The ranges are published estimates from the sources below, as of the dates shown. Material costs, labor rates, tariffs and inflation can change prices after those dates, and your home may differ. Use them to plan a budget, then get written quotes from licensed contractors.
Sources
- Seattle Department of Construction and Inspections — Decks
- Seattle Department of Construction and Inspections — Fences
- SDCI — How Much Will Your Permit Cost? and 2026 fee changes summary
- Angi — How Much Does It Cost to Build a Deck in Seattle, WA? (2025 data)
- Washington Department of Revenue — Custom construction
All sources accessed November 9, 2026.
This guide summarizes published cost estimates and City of Seattle rules. It is not legal advice. Confirm permit requirements with SDCI before work starts, and get written quotes from licensed, bonded contractors. See our disclosure and disclaimer.