Attached ADU (AADU) Permits in City of Lynnwood
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.
Drops the placement canvas on your parcel for attached adu (aadu) scope. Live setback + coverage + easement checks; packet generation when you’re ready.
Permit fees in City of Lynnwood
Fee schedule not yet aggregated — check the City of Lynnwood fee schedule directly.
City of Lynnwood fee scheduleFull Construction Permit (Addition/Alteration) fees. A new ADU connection commonly also triggers a ONE-TIME sewer and/or water connection charge from the utility that serves the property — called a general facility charge, a capacity charge or a system development charge depending on the utility. WHICH UTILITY AND WHICH CHARGE IS A PER-PROPERTY FACT, not a city or county one, and a single lot can sit inside a city for permitting and outside its sewer district. Ask the utility that will actually serve the ADU; this charge is often the largest single line in an ADU budget after construction.
Review timeline
Timeline not yet aggregated — the per-parcel page shows the live estimate.
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.
- Separate address / unit number — required by USPS + 911 dispatch.