Addition permits in City of Issaquah: fees, timeline & requirements (2026)
Everything you need to know about pulling a home addition permit in City of Issaquah, Washington — when one is required, what it costs, how long review takes, what documents are required, and which inspections you can expect. Cited to Community Planning & Development.
Free lookup, no account needed — your lot polygon, zoning, setbacks and overlays, cited to City of Issaquah's source.
When does a home addition need a permit in City of Issaquah?
A permit is required for all single-family/duplex new construction and additions; no exemption is published. Setback / form / intensity per IMC 18.404.
In the source's own words
“This permit is required for construction of single family / duplex new construction and additions.”Source ↗verified 2026-09-24
Required submittals
- site plan with north arrow, property lines, setbacks, existing + proposed structures, lot coverage calculation
- floor plan existing and proposed (dimensioned, 1/4" = 1' min)
- elevations all affected sides (existing + proposed, height-to-grade)
- foundation plan + footing details (if footprint addition)
- framing plan (floor + roof + lateral)
- wall section with insulation values per WSEC
- structural calculations (when ≥500 sqft addition or out of IRC prescriptive envelope)
- WSEC compliance form (Energy Code Compliance Certificate)
- Manual J HVAC sizing calculation for new conditioned area
- window/door schedule with NFRC U-factor and SHGC values
- soils report if footing on slope or expansive soils
Inspection sequence
- foundation/footing
- plumbing rough-in
- electrical rough-in
- mechanical rough-in
- framing
- insulation
- drywall
- final
Contractor specialties needed
general, plumbing, mechanical
Who can do this work in City of Issaquah?
Kolmo Construction is a licensed Washington general contractor — KOLMOL*753JS, active through April 10, 2027, bonded and insured — working throughout City of Issaquah and King County. Kolmo prepares the drawings and submittals, files the home addition permit with Community Planning & Development, carries the project through review and inspections, and performs the construction. Call (206) 410-5100 for a City of Issaquah home addition quote.
Notes & caveats
Submit via MyBuildingPermit.com (paper not accepted). Setback / form / intensity per IMC 18.404; design standards per applicable overlay (Olde Town, Issaquah Highlands, etc.).
Addition permit fee — Washington baseline, not City of Issaquah's own schedule
Worked example for a $120,000 home addition project (building permit). Your actual fee scales with project valuation.
| Building permit fee | $1,105.75 |
| Plan review | $718.74 |
| WA state surcharge | $6.5 |
| Estimated total | $1,830.99 |
Plan-review fee scales with valuation per UBC Table 1-A. State surcharge $6.50 per building permit. Trade permits (E/P/M) separate. Apply via https://mybuildingpermit.com. We have not read City of Issaquah's adopted fee schedule, so this is not City of Issaquah's fee: it walks the standard valuation table most Washington cities adopt by reference, as a rough guide. The real numbers are in City of Issaquah's fee schedule ↗. Impact/utility fees may apply separately.
How to apply yourself
- 1. Confirm your parcel's zoning & overlays. Run an address lookup for your City of Issaquah home addition — we'll pull your specific lot polygon, zoning, setbacks, and any shoreline/ECA/historic overlays.
- 2. Assemble submittals (11).
- 3. Submit through the city portal: Community Planning & Development ↗
- 4. Track review (typical: 45–120 days). Respond to reviewer comments promptly.
- 5. Pay issuance fees (Plan-review fee scales with valuation per UBC Table 1-A. State surcharge $6.50 per building permit. Trade permits (E/P/M) separate. Apply via https://mybuildingpermit.com.) and pick up the permit. Inspection card travels with the job.
Or have Kolmo do it
We pull home addition permits in City of Issaquah every month. We prepare the drawings and submittals, file with Community Planning & Development, handle reviewer comments, and build the project.
Licensed WA general contractor KOLMOL*753JS · bonded & insured
Addition permits in City of Issaquah — FAQ
When does a home addition need a permit in City of Issaquah?
A permit is required for all single-family/duplex new construction and additions; no exemption is published. Setback / form / intensity per IMC 18.404.
How much does a home addition permit cost in City of Issaquah?
For a $120,000 home addition project, the estimated City of Issaquah permit fee is about $1,830.99 — building fee $1,105.75 + plan review $718.74 + surcharges. Fees scale with project valuation per the city schedule.
How long does City of Issaquah take to review a home addition permit?
Typical review window: 45–120 days.