Addition permits in City of Sammamish: fees, timeline & requirements (2026)
Everything you need to know about pulling a home addition permit in City of Sammamish, Washington — when one is required, what it costs, how long review takes, what documents are required, and which inspections you can expect. Cited to Apply via MyBuildingPermit.com..
Free lookup, no account needed — your lot polygon, zoning, setbacks and overlays, cited to City of Sammamish's source.
When does a home addition need a permit in City of Sammamish?
Single-family/duplex additions require a building permit (MBP: Building → Single-Family Residential → Structure Addition). Demolitions, pools, retaining walls, and detached structures require separate permits. A Sewer Availability Certificate is required when the project exceeds 50% of the assessed value or adds plumbing fixtures.
In the source's own words
“Please note that demolitions, pools, retaining walls, and detached structures require submittal of a separate demolition or building permit.”Source ↗verified 2026-09-24
Required submittals
- Acceptance of Financial Responsibility (Affidavit of Applicant Status)
- Historic Resources Affidavit
- Legal Description
- Plan Set (existing + proposed)
- Project Narrative
- Residential Fixture Count Form
- Sewer Availability Certificate (when >50% assessed value or fixtures added)
Inspection sequence
- foundation/footing
- plumbing rough-in
- electrical rough-in
- mechanical rough-in
- framing
- insulation
- drywall
- final
Contractor specialties needed
general, electrical-01-or-02, plumbing, mechanical
Who can do this work in City of Sammamish?
Kolmo Construction is a licensed Washington general contractor — KOLMOL*753JS, active through April 10, 2027, bonded and insured — working throughout City of Sammamish and King County. Kolmo prepares the drawings and submittals, files the home addition permit with Apply via MyBuildingPermit.com., carries the project through review and inspections, and performs the construction. Call (206) 410-5100 for a City of Sammamish 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. Most WA cities use a uniform fee bracket (UBC Table 1-A) for the building permit; plan review fee is typically 65% of building permit fee.
Addition permit fee — Washington baseline, not City of Sammamish'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 Sammamish's adopted fee schedule, so this is not City of Sammamish'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 Sammamish'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 Sammamish 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: Apply via MyBuildingPermit.com. ↗
- 4. Track review. 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 Sammamish every month. We prepare the drawings and submittals, file with Apply via MyBuildingPermit.com., handle reviewer comments, and build the project.
Licensed WA general contractor KOLMOL*753JS · bonded & insured
Addition permits in City of Sammamish — FAQ
When does a home addition need a permit in City of Sammamish?
Single-family/duplex additions require a building permit (MBP: Building → Single-Family Residential → Structure Addition). Demolitions, pools, retaining walls, and detached structures require separate permits. A Sewer Availability Certificate is required when the project exceeds 50% of the assessed value or adds plumbing fixtures.
How much does a home addition permit cost in City of Sammamish?
For a $120,000 home addition project, the estimated City of Sammamish 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.