Basement finish permits in City of Seattle: fees, timeline & requirements (2026)

Everything you need to know about pulling a basement finish permit in City of Seattle, Washington — when one is required, what it costs, how long review takes, what documents are required, and which inspections you can expect. Cited to Seattle Department of Construction & Inspections (SDCI).

Permit required?
Yes — see threshold below
Permit fee
Construction Permit (Addition/Alteration). Plan-review fee scales with valuation. See SDCI 2026 Fee Estimator.
Review timeline

When does a basement finish need a permit in City of Seattle?

Adding habitable rooms requires Construction Permit. Egress window required for any sleeping room (2021 IRC R310). Ceiling-height minimums and emergency-escape openings are common rejection reasons.

Required submittals

  • floor plan w/ egress windows + ceiling heights
  • electrical layout
  • plumbing diagram
  • mechanical / HVAC plan
  • WSEC compliance form

Inspection sequence

  1. rough-in (electrical/plumbing/mechanical)
  2. framing
  3. insulation
  4. drywall
  5. final

Contractor specialties needed

general, electrical-01-or-02, plumbing, mechanical

Notes & caveats

Construction Permit (Addition/Alteration) if adding habitable space. Subject-to-Field-Inspection if scope is limited (no new bedrooms, no structural). Always: electrical, plumbing, mechanical permits for new fixtures/circuits/HVAC. WSEC applies to newly conditioned space.

How to apply

  1. 1. Confirm your parcel's zoning & overlays. Run an address lookup on the main permits page — we'll pull your specific lot polygon, zoning, setbacks, and any shoreline/ECA/historic overlays.
  2. 2. Assemble submittals (5).
  3. 3. Submit through the city portal: Seattle Department of Construction & Inspections (SDCI)
  4. 4. Track review (typical: ). Respond to reviewer comments promptly.
  5. 5. Pay issuance fees (Construction Permit (Addition/Alteration). Plan-review fee scales with valuation. See SDCI 2026 Fee Estimator.) and pick up the permit. Inspection card travels with the job.
City of Seattle resourcesPermit portal ↗Fee schedule ↗