Attached ADU (AADU) Permits in Lakewood
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 Lakewood
Set by the Lakewood fee schedule.
Lakewood fee scheduleLakewood prices an ADU's building permit on the value of the work, set by the Building Official: $805 for the first $50,000 plus $9.00 for each $1,000 more up to $100,000, and $1,255 for the first $100,000 plus $7.25 for each $1,000 more up to $500,000. Plan review is 65% of the building permit fee, one hour at the least, and the $6.50 state building code fee applies; a prescriptive residential mechanical permit is $240. Every permit application carries the City's $90 administrative base fee, mechanical permits excepted, and a 4% technology fee (2026 Fee Schedule). Apply through Lakewood's Online Permit Center (app.oncamino.com/
Review timeline
Not published by Lakewood.
What Lakewood asks for with an attached ADU
Every application (9)
- Residential building permit application, Online Permit Center
- Certificate of Water Availability & Fire Flow
- Pierce County septic approval packet
- Site address
- Pierce County parcel number
- Site plan
- Floor plan
- WSEC energy compliance, prescriptive path
- 2021 WA State Energy Code Form
Where the lot or the work calls for it
Where the ADU adds onto the house or changes its structure
- Drainage and Erosion Control Plan (Stormwater Pollution Prevention Plan)
- Tree Retention Plan
- Foundation plan
- Roof + floor framing plan
- Structural design notes (loads, materials, inspections)
- Structural Calculations
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 critical area, has a steep slope, is in a landslide hazard area, is in an erosion hazard area, is in a seismic hazard area, has a wetland, has a stream or is in a flood zone
- Geotechnical report
From the city’s own documents: City of Lakewood — Residential Building Permit Applications, Required Submittal Items Matrix (October 2025) · City of Lakewood Planning Division — No. P5, Site Plan Requirements (Revised April 15, 2025) · City of Lakewood Building Division — No. B5, Residential Construction Plan Components (Revised April 16, 2025), 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.