Addition permits in Renton: fees, timeline & requirements (2026)
Everything you need to know about pulling a home addition permit in Renton, Washington — when one is required, what it costs, how long review takes, what documents are required, and which inspections you can expect. Cited to Renton Community and Economic Development — Development Services.
Free lookup, no account needed — your lot polygon, zoning, setbacks and overlays, cited to Renton's source.
When does a home addition need a permit in Renton?
Additions always require a building permit — they are expressly excluded from "ordinary repairs" (RMC 4-5-060 §105.2.2). Work started without a permit is subject to a special investigation fee equal to twice the permit fee.
In the source's own words
“nor shall ordinary repairs include an addition to, alteration of...”Source ↗verified 2026-05-29
Required submittals
- Application Form, Building Division (RMC 4-8-120B row "Application Form, Building Division" col "Single Family/Duplex New or Additions")
- Architectural Plans, Detached and 2 Attached Dwellings (RMC 4-8-120B)
- Architectural Elevations (RMC 4-8-120B footnote q: required for SF when changing elevation)
- Biological Assessment / Critical Areas Study — required only when site is in a critical area (RMC 4-8-120B footnote s)
- Drainage Plans (RMC 4-8-120B footnote h: required if project meets Surface Water Design Manual thresholds)
- Structural Plans (RMC 4-8-120B)
- Structural Calculations (RMC 4-8-120B)
- Energy Code Checklist, Residential (per WSEC 2021 R-prescriptive checklist + Renton amendments)
- Geotechnical Report (RMC 4-8-120B — required for projects on sloped or expansive soils)
- Site Plan (RMC 4-8-120B — north arrow, property lines, setbacks, existing + proposed structures)
- Tree Retention/Land Clearing Plan (RMC 4-4-130 — required when site contains significant trees ≥6" DBH outside building footprint)
- Wetlands Report (RMC 4-8-120B footnote a — required when wetlands present)
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 Renton?
Kolmo Construction is a licensed Washington general contractor — KOLMOL*753JS, active through April 10, 2027, bonded and insured — working throughout Renton and King County. Kolmo prepares the drawings and submittals, files the home addition permit with Renton Community and Economic Development — Development Services, carries the project through review and inspections, and performs the construction. Call (206) 410-5100 for a Renton home addition quote.
Notes & caveats
Submittals encoded from RMC 4-8-120B (Building Section Permit Submittal Requirements), Table column "Single Family/Duplex New or Additions". Plan-set must include the items below; site plan must meet Renton standards (north arrow, property lines, setbacks per the underlying R-X zone in RMC 4-2-110, lot coverage calc). Site Plan Review (RMC 4-9-200) is REQUIRED for non-detached SF projects in IL, CO, CN, CD, CA, CV, COR, UC-1, UC-2, R-10, RMH, RM, R-14 zones; detached SF in R-zones is generally exempt from Site Plan Review. Apply via permitting.rentonwa.gov.
Addition permit fee estimate in Renton
Worked example for a $120,000 home addition project (building permit). Your actual fee scales with project valuation.
| Building permit fee | $1,822.29 |
| Plan review | $1,184.49 |
| Technology surcharge | $150.34 |
| WA state surcharge | $6.50 |
| Estimated total | $3,163.62 |
Renton prices an addition's building permit on the value of the work: $1,062.23 for the first $50,000 plus $11.53 for each $1,000 more up to $100,000, and $1,638.89 for the first $100,000 plus $9.17 for each $1,000 more up to $500,000. Plan check is 65% of the permit fee, three review cycles included, and the $6.50 state building code fee applies. A residential plumbing permit is a $69 base fee plus $12 a fixture, a mechanical permit $69 plus $28 for each appliance, fan or gas piping system, and the City's electrical permit for new circuits without a service change $222 at the least; plan review on those permits, where required, is 40% of the permit fee. The City adds its 5% technology surcharge to each of these fees (Fee Schedule 2025-2026). Apply via permitting.rentonwa.gov. Computed from Renton'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 Renton home addition — we'll pull your specific lot polygon, zoning, setbacks, and any shoreline/ECA/historic overlays.
- 2. Assemble submittals (12).
- 3. Submit through the city portal: Renton Community and Economic Development — Development Services ↗
- 4. Track review. Respond to reviewer comments promptly.
- 5. Pay issuance fees (about $3,164 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 Renton Community and Economic Development — Development Services, handles reviewer comments, and builds the project.
Licensed WA general contractor KOLMOL*753JS · bonded & insured
Addition permits in Renton — FAQ
When does a home addition need a permit in Renton?
Additions always require a building permit — they are expressly excluded from "ordinary repairs" (RMC 4-5-060 §105.2.2). Work started without a permit is subject to a special investigation fee equal to twice the permit fee.
How much does a home addition permit cost in Renton?
For a $120,000 home addition project, the estimated Renton permit fee is about $3,163.62 (building fee $1,822.29 + plan review $1,184.49 + surcharges) from Renton's adopted fee schedule. Land use, fire and engineering review, intake, impact and utility fees, where they apply, are charged separately.