Seattle covers most small decks, sheds, and fences that need a permit with a subject-to-field-inspection permit, but environmentally critical areas can push a project into a full permit.
Seattle’s SDCI “common projects” pages for decks, sheds, and fences are written for homeowners: clear numeric triggers, plus zoning and ECA warnings that trip people who only read the building-permit exemption. This article translates those patterns and links you back to the official pages.
National guides: Do I need a building permit? · Deck permits · Shed permits · Fence permits · 10-Minute AHJ Permit Check
City pattern pages: Portland OR · Seattle WA · Denver CO
Seattle’s exemption list vs common-project pages
SDCI’s overview Do You Need a Permit? points to Seattle Residential Code Section R105.2 and Seattle Building Code Section 106.2 for work that usually does not need a permit. It also summarizes small accessory buildings (projected roof area under 120 square feet on a slab), certain retaining walls under 4 feet, fences under 8 feet (with masonry limits), and small open-framed arbors.
For decks, sheds, and fences, the dedicated common-project pages are easier for homeowners than raw code text. Use both: the overview for the legal list, the project pages for “what does this mean on my lot?”
Decks — the 18-inch example (not 30)
Seattle’s deck page (Decks — Construction and Inspections) is a good reminder that cities do not share one national deck height:
- You need a permit to build a deck if it is more than 18 inches above the ground, a roof deck, or in an ECA.
- A more complex addition/alteration construction permit path applies when the deck is more than 8 feet above ground, includes beams 14 feet or longer, is a roof deck, is in an ECA, has solid flooring (no gaps), or exceeds 750 square feet.
Zoning overlays sit on top of the permit trigger. SDCI notes that decks more than 36 inches above ground typically count toward lot coverage in neighborhood residential zones, and decks more than 18 inches face setback limits that do not apply the same way to ultra-low platforms.
If you are used to “30 inches” from IRC-style cities (or Portland’s Brochure 3), Seattle’s 18-inch trigger is a different pattern. Always measure from the ground the way SDCI describes—and read the page for your exact scope.
| Seattle deck pattern (example) | Permit signal | Also watch |
|---|---|---|
| >18" above ground | Usually need a permit | Setbacks in NR zones |
| ≤18" platform (non-ECA) | Often lighter / no permit path* | Confirm current SDCI page |
| >8', >750 sf, long beams, solid floor, roof deck, ECA | Construction addition/alteration path | Plans, site visit |
| >36" above ground | Often counts toward lot coverage | Coverage % in zone |
*Paraphrase of SDCI public pages—verify before you build. Related: national deck guide.
Sheds — 120 square feet roof footprint
Seattle’s shed page (Sheds) lists a multi-part exemption. You generally do not need a permit if all of these are true:
- Total area (or “footprint”) of the shed’s roof is 120 square feet or less
- Single-story building
- Sits on a simple concrete slab, pier blocks, or soil
- Not attached to a house or other building
- Not in or near an ECA
- Used for storage, growing plants, or similar unoccupied uses
Other sheds require a permit; larger or more complex sheds (ECA, over 750 sf, long beams) may need a construction addition/alteration permit rather than a simple subject-to-field-inspection path.
Zoning still limits height (SDCI mentions a common 12-foot height limit for sheds) and lot coverage. Combined footprints of house, garage, shed, and decks 36 inches or more above ground can hit neighborhood residential coverage caps. Setbacks toward the front and sides are often non-negotiable even when the building permit is not required.
National shed patterns: Shed permit requirements.
Fences — eight feet / six feet masonry, then zoning
From SDCI’s fence page (Fences) and the do-you-need-a-permit overview:
- You typically don’t need a permit for a fence with total height of 8 feet or less that does not have masonry or concrete elements over 6 feet (flood-prone locations can still require a construction permit).
- Taller fences need a construction permit; many are subject-to-field-inspection with a site plan.
- Zoning in neighborhood residential and multifamily zones commonly limits fence height to 6 feet plus up to 2 feet of open architectural features—and often 4 feet in a front or street-side setback.
That split—building-permit exemption vs zoning maximum—is why a contractor can say “no permit” while planning still rejects a 7-foot solid front-yard fence. Read both tracks. Corner lots and fences on bulkheads/retaining walls have extra height math on the SDCI page.
More fence guidance: Fence permits & corner lots.
Practical workflow for Seattle homeowners
- Confirm you are in the City of Seattle (not Shoreline, Bellevue, King County unincorporated, etc.).
- Check ECA / steep slope / flood designations for your parcel.
- Open the SDCI common-project page for your exact scope (deck, shed, fence).
- Measure height and roof footprint the way the page defines them.
- If zoning setbacks or coverage look tight, ask land-use coaching before you order lumber.
- Budget for trade permits if you add power, gas, or plumbing.
What applying for a simple Seattle permit actually looks like
Most small backyard projects that do need a permit in Seattle go through the subject-to-field-inspection (STFI) path rather than full plan review. SDCI issues these permits through the Seattle Services Portal, and the fee is based on the value of the project and is due when the permit is issued (SDCI: Subject-to-field-inspection permits).
The rough order SDCI describes:
- Fill out the pre-application online. This is where you describe the deck, shed, or fence and the address.
- Request a pre-application site visit if your lot needs one. This matters most on lots with environmentally critical areas.
- Prepare plans. SDCI asks for plans that are to scale, easy to read, and show both what exists now and what you plan to change.
- Submit and wait for the check. SDCI reviews whether the project really qualifies for STFI and meets the land use code. If it is too big for this path, they tell you how to apply for a regular building permit instead.
- Get the stamped plans and build. Once fees are paid, the permit and stamped plans show up in your portal, and the inspector checks the building code on site.
One detail catches people on hillside lots: SDCI says a geotechnical report is required for exterior work (other than window, siding, or roofing replacement) when the site has steep slope, landslide, liquefaction, or similar critical areas, and if your project needs one it will not qualify for STFI (SDCI). So on a sloped lot, a "simple" deck can turn into an engineered project. Find that out before you get a contractor's quote.
Trees near the deck, shed, or fence
Seattle's tree rules run on their own track. SDCI's tree protection page says the rules limit tree removal and can require replacement trees as part of a development permit, and that tree work tied to a construction project may need a permit (SDCI: Tree protection code).
If you hire a tree service, there is also a public notice step. Whether or not a permit is needed, the tree service provider has to post a notice on the SDCI website at least 3 full business days before reportable work, and 6 full business days before removing any tree 6 inches or more in diameter at standard height (SDCI). In practice, that means a tree in the way of a new shed is not a same-day job. Plan the week around it, and ask the tree company whether they have posted the notice.
Street trees are a separate matter. SDCI points owners to SDOT for trees in the right-of-way, so a fence along the sidewalk that disturbs a street tree's roots is a question for SDOT, not just SDCI.
Common Seattle mistakes
- Using a 30-inch deck rule from another city. Seattle's trigger is 18 inches.
- Checking the building exemption but not zoning. A shed can be exempt from a building permit and still break a setback or the lot coverage limit.
- Ignoring the critical area map. A slope or wetland designation can change both the permit type and the paperwork.
- Taking out a tree first and asking later. The tree notice and any tree permit come before the saw, not after.
- Assuming a suburb follows Seattle. Shoreline, Bellevue, and unincorporated King County have their own rules.
Seattle STFI permit checklist from start to close
SDCI lays out the subject-to-field-inspection (STFI) process in steps (SDCI subject-to-field-inspection permit page):
- Free help first: SDCI offers 20 minutes of free video coaching; one-hour sessions cost a fee.
- Pre-application: complete it in the Seattle Services Portal with a site plan and a full legal description.
- Site visit: required if you disturb more than 750 square feet of land or any land on an environmentally critical area (ECA) site, with some exceptions.
- ECA documents: exterior work on some ECA sites needs a topographic survey or geotechnical report, and a project that needs either does not qualify for STFI unless the requirement is waived.
- Fees: based on project value, mostly due at intake, plus a technology fee.
- Validity: the permit is valid for 18 months after issue; longer jobs need a renewal.
- On site: display the permit where it can be seen, request inspections, and close the permit when done.
Source: SDCI subject-to-field-inspection permit page.
For how these limits compare across cities, see our permit-free limits by city table.
FAQ
Can I apply for a Seattle deck or fence permit online?
Yes. SDCI issues subject-to-field-inspection permits through the Seattle Services Portal, and the pre-application and site visit requests are also online (SDCI).
How much does a small Seattle permit cost?
SDCI does not publish one flat price for these jobs. Fees for STFI permits are based on the value of your project, so a bigger deck costs more to permit than a small one. Ask for an estimate when you apply.
Do I need a permit to remove a tree for my shed?
It depends on the tree and the project. Tree work that is part of a construction project may need a permit, and a tree service has to post public notice before reportable work either way (SDCI). SDCI has staff arborists who answer these questions.
How long is a Seattle STFI permit good for?
SDCI says the permit is valid for 18 months after the issue date. If the work takes longer, apply for a renewal.
Can I get free help before applying in Seattle?
Yes. SDCI offers 20 minutes of free video coaching for drainage, land use, geotechnical, or construction permit questions.
Official Seattle sources cited
Last checked: October 2026.
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