Seattle permits most residential decks without plan review: under 18 inches needs no permit, and up to 14 feet above grade a subject-to-field-inspection permit typically issues within a few working days. The catch is structural: Seattle requires a 60 psf deck live load, half again the model code.
This page carries the sourced permit facts for Seattle and what Evalation does with them: design the deck in live 3D on the first visit, price it from the design, and generate the sheet set the application needs. The playbook for every city is at the permit-ready blueprints guide, and the trade page is at /for/deck-builders.
Seattle decks are permitted by the Seattle Department of Construction and Inspections, and the system is friendlier than its reputation. A deck less than 18 inches above grade, not over a basement or another story, and outside an environmentally critical area needs no permit at all. Above that, most residential decks qualify for a subject-to-field-inspection permit, STFI, which means no full plan review: you submit, the permit issues, and the building inspector verifies code compliance in the field as you build.
The STFI window got wider this fall. Tip 316, updated October 29, 2026, allows STFI for single-family and duplex decks up to 14 feet above grade, up from the old 8-foot limit, as long as the deck is not on a roof or over enclosed space like a garage or basement. SDCI says it typically processes STFI permits within a few working days of filing. Decks that fall outside STFI run as a full addition and alteration permit with plan review, where SDCI publishes a 30-day goal for single-family additions and reported 64 calendar days at the 75th percentile as of its current performance page.
The submission itself is lean: a signed STFI checklist, a to-scale site plan showing structures, property lines, and distances, and elevation drawings, filed electronically through the Seattle Services Portal with the fee paid at application. Stamped plans are rarely required. SDCI's own deck page says deck drawings rarely need a stamp from an architect or engineer, with two exceptions that matter: a design outside the Seattle Residential Code's prescriptive criteria, and a ledger connection that does not meet SRC R507.9.1.3. Both put an engineer back in the loop.
What makes Seattle genuinely different is the structure math. The city amended the deck live load from the model code's 40 psf to 60 psf, so spans and posts sized from a generic table can come up short here. Snow load is 20 psf, wind is 98 mph ultimate, seismic category D2, and footings only need to reach 12 inches of frost depth. All of it comes from the 2021 Seattle Residential Code, in force since November 15, 2024, with the next code cycle not expected before mid-2027. Sources: seattle.gov SDCI Decks page, Tip 316, construction permit performance page, and 2021 SRC Chapter 3, all accessed November 4, 2026.
Evalation Lab designs the deck in live 3D with the homeowner watching, on the first visit. The price comes off the design while you are still standing in the yard, and when the design is settled, the Lab generates the standard four-sheet permit set from it: S-1 for the structure, A-1, A-2, and A-3 for the plans, elevations, and details.
For an STFI deck, Seattle asks for a signed checklist, a to-scale site plan, and elevations, categories the Lab’s set covers from the design itself; just mind the 60 psf live load when you frame the structure. Check the generated set against the city's published checklist before you submit, and the first submission goes in clean.
Evalation Lab generates the standard sheet set most jurisdictions require, S-1, A-1, A-2, and A-3, from the finished deck design in under an hour.
Yes, once the deck is more than 18 inches above grade, over another story, a roof deck, or in an environmentally critical area. Under all of those thresholds, no permit, though the deck still has to meet code. Source: SDCI, seattle.gov, accessed November 4, 2026.
Rarely. SDCI states deck drawings seldom need an architect or engineer stamp. The exceptions are decks outside the prescriptive criteria of the Seattle Residential Code and ledger connections that do not meet SRC R507.9.1.3, both of which require engineer-stamped plans.
For STFI-eligible decks, which covers most of them up to 14 feet above grade, SDCI says it typically processes the permit within a few working days. Full plan review for decks outside STFI carries a published 30-day goal and currently runs longer in practice.
The 60 psf deck live load. Seattle amended the model code’s 40 psf upward, so framing sized from a generic span table may not pass here. The flip side: a mild 12-inch frost depth and a permit path with no plan review for most decks.
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