Yes, most new decks in Seattle need a building permit. You need one if the deck is more than 18 inches above the ground, if it sits on a roof, or if the lot is in an environmentally critical area such as a landslide-prone or flood-prone zone. A low deck under 18 inches outside those areas usually needs no permit, but it still has to meet the building code.
This guide covers the City of Seattle rules from the Seattle Department of Construction and Inspections (SDCI): which permit applies, how close to the property line a deck can go, what the inspector checks and when a repair or replacement needs a permit. Neighboring cities and unincorporated King County run their own permit offices with their own rules.
Planning a new deck or a replacement inside Seattle? Talk it through with our deck builders, free: (206) 202-8768.
When a Deck Needs a Permit in Seattle
SDCI asks for a permit when the deck meets any one of three conditions:
- It is more than 18 inches above the ground.
- It is a roof deck, built on top of part of the building.
- It is in an environmentally critical area (ECA), for example a landslide-prone or flood-prone area.
A deck, platform or walk under 18 inches that is not over a basement or another story usually needs no permit, according to the city’s permit exemptions. Height is measured from the ground below the deck, so a deck that starts at grade can still cross 18 inches where the yard slopes away.
Skipping the permit does not skip the code. A low deck still has to meet the structural, stair and railing rules below, and the zoning rules on where it can go.
Which Permit: Subject-to-Field-Inspection or a Full Construction Permit
Most decks qualify for a subject-to-field-inspection (STFI) permit, Seattle’s simpler construction permit for small projects. It asks for fewer plans, and the inspector checks the building code on site. A larger or more complex deck needs a full addition or alteration construction permit instead.
| Your deck | Permit |
|---|---|
| 18 inches or lower, not on a roof, not in an ECA | Usually no permit |
| More than 18 inches and up to 8 feet high | Subject-to-field-inspection permit |
| More than 8 feet above the ground | Addition or alteration permit |
| Beams 14 feet or longer | Addition or alteration permit |
| Roof deck | Addition or alteration permit |
| In an environmentally critical area | Addition or alteration permit, after a site visit |
| Solid deck surface with no gaps between boards | Addition or alteration permit |
| More than 750 square feet | Addition or alteration permit |
A raised deck on a sloped lot, a large custom deck design or a rooftop deck usually lands in the second group, so plan the permit into the schedule from the start.
Do You Need a Permit to Repair or Replace a Deck?
Seattle’s minor repair rule exempts repairs or alterations that cost $6,000 or less in any six-month period, counted at the fair market value of labor and parts, even if you do the work yourself. Two limits come with it: any work on load-bearing supports needs a permit no matter how small, and the exemptions do not apply in an environmentally critical area.
- Swapping deck boards, railing parts or stair treads: usually no permit.
- Replacing joists, beams, posts or the ledger: this is load-bearing work, so plan on a permit.
- Tearing out and rebuilding the deck: the rebuild follows the same rules as a new deck.
Our repair-or-replace guide shows how to tell surface wear from frame damage, and a full deck replacement is permitted like a new build.
How Close to the Property Line Can a Deck Be?
Seattle’s land use code limits where a deck can go, separately from the building permit. The SDCI deck page sets these limits for neighborhood residential zones:
- Decks more than 18 inches above the ground cannot sit within 10 to 15 feet of the front property line or within 3 to 5 feet of either side property line.
- At the rear, the required distance is 5, 10 or 15 feet, depending on the number of units on your lot.
- Decks more than 36 inches above the ground count toward lot coverage, which is limited to 50 percent of the lot in the NR1, NR2 and NR3 zones.
- Decks under 18 inches have no placement limit and decks under 36 inches have no size limit, unless the deck is in or near an environmentally critical area.
On a tight city lot, these limits decide the size and shape of a raised deck before materials do, so they are checked during design.
What the Inspector Checks on a Seattle Deck
SDCI lists the main building code requirements for decks:
| Part | Requirement |
|---|---|
| Structure | Designed for a live load of at least 60 pounds per square foot |
| Ledger | Connected to the house so it will not pull away in an earthquake (Seattle Residential Code R507.9.1.3, or an engineered connection) |
| Guardrail | Required when the deck is more than 30 inches above the surface below; at least 36 inches tall, openings under 4 inches |
| Glass guardrail | Special requirements (Seattle Building Code 1015.2.1 and 2407); may need a structural engineer |
| Stairs | Risers up to 7-3/4 inches, treads at least 10 inches, width at least 36 inches |
| Handrail | Required with four or more risers; 34 to 38 inches above the tread nosing, grip 1-1/4 to 2 inches |
| Wood near the ground | Treated or naturally decay-resistant wood wherever it touches concrete close to the earth |
The ledger and the railing are where inspections most often find problems on older decks, which is why a deck inspection starts there. The railing rules are spelled out in our Seattle deck railing code guide.
Decks in Environmentally Critical Areas
Much of Seattle sits on hillsides, shorelines and slopes the city maps as environmentally critical areas, such as landslide-prone and flood-prone areas. In or near one, the usual exemptions fall away: even a low deck or a small repair can need a permit.
Before applying for any construction permit there, SDCI requires a pre-application site visit, and the visit decides which permit the project is eligible for. Expect a longer timeline and plan the deck design around what the visit allows.
How to Get a Deck Permit in Seattle
SDCI issues subject-to-field-inspection permits through the Seattle Services Portal:
- Research the zoning limits and code requirements for your lot.
- Start the application in the Seattle Services Portal.
- Submit the plans. Deck drawings rarely need an architect’s or engineer’s stamp; anyone with drafting skills can prepare them.
- SDCI screens the plans to confirm the deck qualifies and meets the land use code. This screening takes a few days, and SDCI may ask for more information.
- Pay the fees and receive the permit and stamped plans in the portal. Fees are based on the value of the project, plus a technology fee.
- Print the permit and plans, keep them on site and schedule the field inspections. The inspector reviews the code requirements on site.
A deck that does not qualify for the simpler permit is redirected to a regular building permit, which takes longer.
Why the Permit Is Worth It
SDCI lists three practical reasons to permit the work: it supports resale value, it helps make sure your insurance company covers repairs, and it avoids complaints about unpermitted work. A buyer’s inspector will look at a raised deck, and an unpermitted one can slow a sale.
For a new deck installation or a rebuild, the permit and its inspections are part of the schedule. The Seattle deck cost guide shows how a project is priced before that step.
Seattle Deck Permit: Common Questions
How high can a deck be without a permit in Seattle?
In Seattle a deck up to 18 inches above the ground usually needs no permit, as long as it is not a roof deck, not over a basement or another story and not in an environmentally critical area. Above 18 inches, SDCI requires a permit. Even a low deck must still meet the building code and the zoning limits.
Do I need a permit to replace deck boards in Seattle?
Replacing deck boards, railing parts or stair treads usually needs no permit in Seattle when the work costs $6,000 or less in any six-month period. Replacing joists, beams, posts or the ledger is work on load-bearing supports, which SDCI says needs a permit no matter how small the job.
How long does a deck permit take in Seattle?
For a subject-to-field-inspection permit, SDCI says the application and screening take a few days once the plans are complete. A deck that needs a full addition or alteration permit, or one in an environmentally critical area that needs a pre-application site visit, takes longer. How long deck permits have actually taken, year by year, is in our Seattle deck permit data.
Does it cost money to get a deck permit in Seattle?
Yes. A deck that needs a Seattle permit pays a fee to SDCI, collected when the permit is issued, and the amount follows the value of the project. A low deck that needs no permit has no permit fee.
How much does a deck permit cost in Seattle?
Seattle deck permit fees are based on the value of the project, plus a technology fee, and they are due when the permit is issued. SDCI publishes the fee schedule in its Fee Subtitle, so the fee is worked out from the project value at application.
Do I need an engineer or architect for a deck permit?
Usually not. SDCI says deck drawings rarely need a professional’s stamp and anyone with drafting skills can prepare them. An engineer is common for a glass guardrail, an engineered ledger connection or a complex deck in an environmentally critical area.
How far from the property line does a deck have to be in Seattle?
In neighborhood residential zones, a deck more than 18 inches high has to stay 10 to 15 feet from the front property line, 3 to 5 feet from each side line and 5, 10 or 15 feet from the rear line depending on the number of units on the lot. Decks under 18 inches have no placement limit outside critical areas.
Plan Your Deck With the Permit in Mind
Call with your lot, the height you have in mind and a few photos. At the free on-site estimate we measure the height and the setbacks, check the ledger wall and tell you which permit the deck is likely to need. The written estimate states who handles the permit. Our Seattle deck builders check the permit question at every estimate. Up to 25% off your deck project. Free on-site estimate, no obligation.