ADU Permits in Lynnwood
Rules for detached (DADU) and attached (AADU) accessory dwelling units in Lynnwood, Snohomish County.
Free lookup. We’ll resolve your zoning, setbacks, and which ADU types are allowed on your specific parcel.
Choose an ADU type for your parcel
State law (RCW 36.70A.681) requires Lynnwood to allow two ADUs on a lot in a single-family zone — one attached and one detached, two attached, or two detached — except on lots with critical areas or their buffers. An address’s own page checks its lot’s zoning.
DADU — Detached
Backyard cottage with its own foundation and roof. Most flexibility on layout.
AADU — Attached
Part of the house or built onto it: a converted basement or garage, or an addition.
Pre-approved plans
Detached ADU designs city staff have already reviewed and approved.
Lynnwood permit-process facts
ADU permit fees
Set by the Lynnwood fee schedule.
Fee scheduleLynnwood prices an ADU's building permit on the value of the work, by the ICC valuation table or the square footage, whichever is greater: $1,181.86 for the first $50,000 plus $12.62 for each $1,000 more up to $100,000, and $1,812.71 for the first $100,000 plus $10.32 for each $1,000 more up to $500,000. Plan review is 65% of that fee. For new construction, the plumbing and mechanical permits are each 10% of the building permit fee; in an addition they are $257 for up to 4 fixtures or pieces of equipment and $22 for each one more. The City issues the electrical permit, priced for new construction on its electrical valuation table, $114 up to $1,000. A 2.5% technology fee is added (LMC 3.104).
Review timeline
Not published by Lynnwood.
HB 1337 conformance
Lynnwood permits at least two ADUs per single-family lot, with no owner-occupancy requirement and parking limits that respect the HB 1337 ceilings.
These are Lynnwood’s ADU rules as Kolmo reads them; an address’s own page adds its setbacks, easements and critical-area buffers. Source: app.leg.wa.gov, last verified 2026-09-07.
ADU permits in Lynnwood — FAQ
Does Lynnwood allow detached ADUs (DADUs)?
Yes. Washington's HB 1337 (RCW 36.70A.681) requires Lynnwood to allow at least two accessory dwelling units on a lot in a single-family zone within the urban growth area, attached or detached in any combination, except on lots with critical areas or their buffers.
What is the maximum ADU size in Lynnwood?
State law bars a city from setting a maximum ADU size below 1,000 sq ft of gross floor area (RCW 36.70A.681(1)(f)). Lynnwood's own maximum may be higher — the per-parcel page shows it with the city's code citation.