Attached ADU (AADU) Permits in Everett
An ADU built inside or attached to the primary residence — basement conversion, garage conversion, or bump-out addition. Lower cost; constrained by the primary footprint.
Free lookup: your lot’s zoning and setbacks, with an attached ADU placed on it to move and turn.
Permit fees in Everett
Set by the Everett fee schedule.
Everett fee scheduleEverett sets an ADU's valuation at $193 a square foot and prices the building permit on it: $818.75 plus $21.75 for each $1,000 over $25,000 up to $50,000, $1,362.50 plus $20.75 for each $1,000 over $50,000 up to $100,000, and $2,400 plus $8.75 for each $1,000 over $100,000 up to $500,000. Plan review adds 75% of that fee and Planning's review 10%, plus the $6.50 state building code fee. For a new dwelling unit the mechanical permit is the $130 base fee plus $60 for up to 1,000 square feet of conditioned floor space or $90 up to 2,000; plumbing is $130 plus $20 for each fixture; and the City's electrical permit is $100 under 1,000 square feet or $150 up to 2,000. The transportation impact fee for an ADU is $3,115, but a net increase of one ADU triggers none; ADUs pay no school impact fee; the parks impact fee ($1,133 for a studio or one bedroom, $2,268 for two, $3,401 for three or more) is halved for one or two ADUs added to a lot whose house stays. Where the ADU takes a new 3/4-inch City water meter, water and sewer system development fees are $9,433 ($5,159 water, $4,274 sewer), and new impervious area pays $0.3624 a square foot in stormwater system development fees.
Review timeline
Typical: 30–90 business days
Measured, every ADU type: half issued within 312 days of application, 80% within 45475 permits, last 12 months. Source: City of Everett building permits, data.everettwa.gov dataset 3w3u-656c (residential types).
What Everett asks for with an attached ADU
Every application (10)
- Residential Building permit application (Accessory dwelling unit (ADU or DADU)), online permitting portal
- Submittal Checklist Worksheet, completed and signed
- Site address
- Legal description (from Snohomish County Assessor)
- Snohomish County tax parcel ID
- Site plan
- Site Work permit, applied for at the same time
- Floor plan
- WSEC energy compliance, prescriptive path
- Energy Code Compliance Worksheets: the City's Residential Energy Code compliance checklist and WSU's 2021 forms
Where the lot or the work calls for it
Where the ADU adds onto the house or changes its structure
- Foundation plan
- Roof + floor framing plan
- Structural design notes (loads, materials, inspections)
Where the ADU adds onto the house or changes its outside walls, windows or roof
- Typical building / wall section
- Building elevations N/S/E/W
- Major materials schedule
Where the work changes the outside walls, windows or roof
- Glazing + door schedule (NFRC U-factor / SHGC)
Where the lot has a wetland, has a stream or has fish and wildlife habitat
- Critical Area/Mitigation Report (EMC 19.37)
Where the lot has a steep slope or is in a landslide hazard area
- Geotechnical report
From the city’s own documents: City of Everett — Residential Building Permit Submittal Checklist, Subtype: Accessory Dwelling Unit (ADU or DADU) (Updated 06/01/2026), last read October 22, 2026. An address’s own page checks its lot for slopes, flood zones and critical areas.
AADU-specific requirements
- Egress on every bedroom — IRC R310 net clear opening ≥5.7 sf; sill ≤44″ from floor.
- Smoke + CO alarms — interconnected throughout primary + AADU per IRC R314/R315.
- 1-hr separation — required between AADU and primary in some cases; otherwise a continuous draft stop.
- Independent kitchen + bath — full plumbing + cooking provision in the AADU.
- Address or unit number — the city or county assigns addresses; ask the permit center whether the unit gets its own.