I heard Seattle allows two ADUs per lot. Is that true everywhere or only in some zones?

Question

Marcus Golen · Accepted Answer

Yes — under Seattle’s 2019 ADU reform, most single-family lots in NR1, NR2, NR3, LR, and RSL zones can have one AADU + one DADU (two ADUs total) on the same lot, with no owner-occupancy requirement. Exceptions: lots in environmentally critical areas, some shoreline overlays, and parcels under 3,200 sqft may be limited. Always pull a Property Report from SDCI Maps before assuming two ADUs are feasible.

Answer

No. Seattle removed the owner-occupancy requirement in 2019. You can build an ADU as a pure investment property and rent both the main house and the ADU. Bellevue, Kirkland, and Redmond have similar rules — but Mercer Island and a few smaller cities still require owner-occupancy. Confirm on the city’s own ADU page befo

Answer

In NR1/NR2/NR3 zones: 5 ft side setback, 5 ft rear setback (or 0 ft if the DADU is on an alley with vehicular access), and 6 ft minimum separation from the main house. In LR zones, side and rear setbacks drop to 5 ft with no main-house separation requirement. Maximum DADU height is 18 ft for a single-story footprint, 2

Answer

As of 2026, Kirkland allows one ADU per single-family lot (AADU or DADU, not both) in RSA-1, RSA-4, and RSA-6 zones. Maximum DADU size: 1,000 sqft or 50% of main house, whichever is smaller. Height cap: 18 ft. No owner-occupancy. Lot minimum 5,000 sqft for DADUs, no minimum for AADUs. Permit timeline runs 14–22 weeks.

Answer

Redmond allows DADUs in R-4, R-5, R-6, and R-8 zones with a 6,000 sqft lot minimum and a maximum DADU size of 1,000 sqft. Height cap is 18 ft. Owner-occupancy is not required since 2022. Redmond’s permit timeline runs 16–24 weeks and is more design-review heavy than Seattle, especially for lots in tree retention areas.

Answer

Yes — Seattle removed the lot-size minimum for DADUs in 2019. The constraint becomes footprint math: setbacks (5 ft sides + 5 ft rear) and lot coverage (35% in NR1, 45% in LR) usually leave a 16x24 ft DADU footprint on a 3,200 sqft lot. That fits a 380–450 sqft single-story or 600–750 sqft two-story DADU. You may need

Answer

In Seattle, an ADU can be a short-term rental only if you (the operator) live on-site in either the main house or the ADU. You cannot operate two unhosted STRs from one property. You also need a Short-Term Rental Operator License ($75/year) and the unit must be registered. STRs that don’t meet the on-site requirement f

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