Which cities is the Kolmo permit lookup verified for?

Ten cities: Seattle, Bellevue, Kirkland, Redmond, Sammamish, Issaquah, Renton, Kent, Federal Way, and Mercer Island. For these, every fee, threshold, and timeline is sourced from the city directly with the exact quote, URL, and the date Kolmo sourced it; an automated scanner monitors the source pages daily for drift. Outside these ten cities address lookup still works and we render the parcel and Washington-state baseline code, but per-city specifics are flagged as unverified.

Does the lookup cover unincorporated King, Pierce, or Snohomish County?

Address lookup works and parcels resolve to the county building department, but unincorporated coverage is currently baseline-only — Washington-state IRC, IBC, and WSEC plus state critical-area rules. Per-county fee and code deviations have not been verified to the same standard as the ten verified cities.

Will this replace calling the permit center?

For most homeowner projects — decks, kitchens, bathrooms, ADUs, fences, siding, windows, flooring, roofing, HVAC, electrical, plumbing — the published answer matches what the permit center will say, and the homeowner can submit with a pre-filled application packet. For variances, conditional uses, or unusual scope, calling the city planner is still recommended.

Where does the address go after submission?

The address is geocoded via Google Maps to identify the correct county, then queried against public county GIS endpoints. Parcel data is cached for 30 days. The address is not contacted, sold, or shared with third parties.

Who built this — and why?

Built by Kolmo Construction, a licensed Seattle-area general contractor. The team works with permit code daily and built this to fix the public web's poor coverage of homeowner permit questions. The lookup is free; if a homeowner wants a contractor for the project, Kolmo is one option.

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

Everything you need to know about pulling a home addition 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). Pay 75% of plan-review + permit fees at application acceptance. See SDCI 2026 Fee Estimator.

Review timeline

30–120 days

When does a home addition need a permit in City of Seattle?

Any additional floor area requires Construction Permit (Addition or Alteration). Plan review required. ECA + lot coverage + setback compliance verified at intake.

Required submittals

architectural plans
structural calcs
WSEC compliance form
site plan w/ setbacks + lot coverage
survey if near setback or in ECA

Inspection sequence

footing
foundation
framing
rough-in (electrical/plumbing/mechanical)
insulation
drywall
final

Contractor specialties needed

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

Notes & caveats

Full structural plan review. Lot coverage limits apply (NR zones: 35% or 1,000sf + 15% for small lots). Energy code applies to new conditioned space.

Addition permit fee estimate in City of Seattle

Worked example for a $120,000 home addition project (building permit). Your actual fee scales with project valuation.

Building permit fee	$1,437.48
Plan review	$934.36
Technology surcharge	$71.87
WA state surcharge	$4.5
Estimated total	$2,448.21

$100,001 to $500,000: $993.75 + $5.60 per $1,000 over $100,000 (Seattle SDCI applies ~1.30× multiplier vs. UBC baseline; verify against current SDCI Fee Subtitle for exact figures) Computed from the City of Seattle fee bracket schedule · source ↗. Impact/utility fees may apply separately.

How to apply

1. Confirm your parcel's zoning & overlays. Run an address lookup for your City of Seattle home addition — we'll pull your specific lot polygon, zoning, setbacks, and any shoreline/ECA/historic overlays.
2. Assemble submittals (5).
3. Submit through the city portal: Seattle Department of Construction & Inspections (SDCI) ↗
4. Track review (typical: 30–120 days). Respond to reviewer comments promptly.
5. Pay issuance fees (Construction Permit (Addition/Alteration). Pay 75% of plan-review + permit fees at application acceptance. See SDCI 2026 Fee Estimator.) and pick up the permit. Inspection card travels with the job.

Compare this against other cities

Side-by-side home addition requirements across all 10 verified Seattle-area cities.

All City of Seattle permits

Every project type — ADU, addition, kitchen, bath, deck, fence, and more — for City of Seattle.

Addition permits in City of Seattle — FAQ

When does a home addition need a permit in City of Seattle?

Any additional floor area requires Construction Permit (Addition or Alteration). Plan review required. ECA + lot coverage + setback compliance verified at intake.

How much does a home addition permit cost in City of Seattle?

For a $120,000 home addition project, the estimated City of Seattle permit fee is about $2,448.21 — building fee $1,437.48 + plan review $934.36 + surcharges. Fees scale with project valuation per the city schedule.

How long does City of Seattle take to review a home addition permit?

Typical review window: 30–120 days.

City of Seattle resourcesPermit portal ↗Fee schedule ↗