Addition permits in Federal Way: fees, timeline & requirements (2026)
Everything you need to know about pulling a home addition permit in Federal Way, Washington — when one is required, what it costs, how long review takes, what documents are required, and which inspections you can expect. Cited to Federal Way Department of Community Development.
Free lookup, no account needed — your lot polygon, zoning, setbacks and overlays, cited to Federal Way's source.
When does a home addition need a permit in Federal Way?
Any increase to building footprint or conditioned floor area requires a building permit. A Certificate of Water Availability with fire-flow calculations is required for additions or any change to the building footprint.
In the source's own words
“Certificate of Water Availability (for additions or any changes to building footprint) w/Fire Flow Calculations.”Source ↗verified 2026-05-29
Required submittals
- Building Permit Application
- Single Family Remodel Checklist (#156)
- Complete set of drawings
- Structural calculations (if structural alterations)
- Floor plan + framing plan + building cross sections
- Certificate of Water Availability w/ fire-flow calculations
- Smoke/CO detector notes
Inspection sequence
- Foundation/footing
- Plumbing rough-in
- Electrical rough-in
- Mechanical rough-in
- Framing
- Insulation
- Drywall
- Final
Contractor specialties needed
General contractor · Electrician (journey-level 01 or residential 02) · Plumber · Mechanical contractor
Who can do this work in Federal Way?
Kolmo Construction is a licensed Washington general contractor — KOLMOL*753JS, active through April 10, 2027, bonded and insured — working throughout Federal Way and King County. Kolmo prepares the drawings and submittals, files the home addition permit with Federal Way Department of Community Development, carries the project through review and inspections, and performs the construction. Call (206) 410-5100 for a Federal Way home addition quote.
Notes & caveats
2021 IRC R301 governs framing. WSEC R402.1 sets envelope requirements. New conditioned space requires Manual J HVAC sizing. Lateral load path continuity required for vertical additions.
Addition permit fee estimate in Federal Way
Worked example for a $120,000 home addition project (building permit). Your actual fee scales with project valuation.
| Building permit fee | $2,606.98 |
| Plan review | $1,694.54 |
| Automation fee (5% of the permit fee, $43 minimum) | $130.35 |
| WA state surcharge | $6.50 |
| Estimated total | $4,438.37 |
Federal Way prices an addition's building permit on the value of the work (the ICC's building valuation data, or a bid the Building Official approves), off Valuation Table A: $1,531.67 for the first $50,000 plus $16.24 for each $1,000 more up to $100,000, and $2,343.58 for the first $100,000 plus $13.17 for each $1,000 more up to $500,000. Plan review is 65% of the building permit fee, single-family plans carry a $60 digitizing fee, and the $6.50 state building code fee applies. Plumbing and mechanical work is priced on the same table by its installation value, and the City's own electrical permit on Valuation Table B, $96.21 up to $1,000 of installation value; plan review, where plans are reviewed, is 65% of each permit fee. Each permit carries the automation fee, the greater of $43 or 5% of the permit fee (2026 Fee Schedule). Computed from Federal Way's adopted fee schedule · source ↗. Land use, fire and engineering review, intake, impact and utility fees, where they apply, are charged separately.
How to apply yourself
- 1. Confirm your parcel's zoning & overlays. Run an address lookup for your Federal Way home addition — we'll pull your specific lot polygon, zoning, setbacks, and any shoreline/ECA/historic overlays.
- 2. Assemble submittals (7).
- 3. Submit through the city portal: Federal Way Department of Community Development ↗
- 4. Track review. Respond to reviewer comments promptly.
- 5. Pay issuance fees (about $4,438 for a $120,000 project) and pick up the permit. Inspection card travels with the job.
Or have Kolmo do it
Kolmo prepares the drawings and submittals, files with Federal Way Department of Community Development, handles reviewer comments, and builds the project.
Licensed WA general contractor KOLMOL*753JS · bonded & insured
Addition permits in Federal Way — FAQ
When does a home addition need a permit in Federal Way?
Any increase to building footprint or conditioned floor area requires a building permit. A Certificate of Water Availability with fire-flow calculations is required for additions or any change to the building footprint.
How much does a home addition permit cost in Federal Way?
For a $120,000 home addition project, the estimated Federal Way permit fee is about $4,438.37 (building fee $2,606.98 + plan review $1,694.54 + surcharges) from Federal Way's adopted fee schedule. Land use, fire and engineering review, intake, impact and utility fees, where they apply, are charged separately.