ADU & backyard cottage rules in Kent, WA
Kent renamed its residential zones in 2025. The ReCode (Ordinance 4517, effective July 30, 2025) turned the old SR districts into NR zones: SR-1 became NR-L, SR-3 became NR-S, SR-6 became NR-2 and SR-8 became NR-3. A parcel record may still carry the old name; the lot area is the same.
Kent is one of the few cities whose code gives a backyard cottage its own, looser setbacks. A detached ADU in the rear half of the lot may sit within 2 feet of the side and rear lines (KCC 15.08.350), while the front setback stays the zone's. A detached ADU is also capped at 24 feet tall whatever the zone allows the house.
Parking is one off-street space per ADU, unless the lot is within a half-mile walk of a major transit stop (KCC 15.05.040). Every NR zone allows up to four homes per lot under the middle-housing law, HB 1110.
The table shows the zone standards and, where Kent sets them, the detached ADU setbacks.
The rules our engine reads for Kent
| Zone | Coverage | Height | Smallest lot | Setbacks front / side / rear | Detached ADU setbacks | Also |
|---|---|---|---|---|---|---|
| NR-L | 30% | 35 ft | 34,700 sq ft | 20 ft / 15 ft / 15 ft | 20 ft / 2 ft / 2 ft | up to 4 homes per lot |
| NR-S | 45% | 35 ft | 9,600 sq ft | 10 ft / 5 ft / 5 ft | 10 ft / 2 ft / 2 ft | up to 4 homes per lot |
| NR-2 | 50% | 28 ft | 5,700 sq ft | 10 ft / 5 ft / 10 ft | 10 ft / 2 ft / 2 ft | up to 4 homes per lot |
| NR-3 | 55% | 35 ft | 4,000 sq ft | 10 ft / 5 ft / 20 ft | 10 ft / 2 ft / 2 ft | up to 4 homes per lot |
Rules checked 2026-10-25. Sources: Kent City Code 15.04.170, residential development standards (Ord. 4517, 2025).
What this means for your lot
- Find your zone code on your parcel record or Kent's zoning map, then read its row above: the setbacks and the lot coverage limit decide how much of the lot a second home can use.
- Whether a cottage fits is a question of room, not permission: setbacks, what is already built, trees and slope leave a buildable area. The 3D check places a home inside it and tells you when it breaks a rule.
- Washington's HB 1337 sets the floor in urban areas — two ADUs per lot, no owner-occupancy rule, and a size cap no lower than 1,000 sq ft — so the local table above is what is left to check.
Common questions
Can I build a detached ADU (backyard cottage) in Kent?
Washington's HB 1337 requires cities and counties that plan under the Growth Management Act to allow two ADUs per lot in urban growth areas, in any mix of attached and detached. Whether one fits on your lot in Kent depends on its setbacks and coverage, which are in the table on this page.
How big can an ADU be in Kent?
State law does not allow a cap below 1,000 sq ft of floor area. The local cap is not in our tables yet — check the code.
Do I need parking for an ADU in Kent?
1 off-street space per ADU unless within a 1/2-mile walk of a major transit stop (KCC 15.05.040). State law allows no more than one space per unit on lots under 6,000 sq ft and two on larger lots, and none within a half-mile walk of a major transit stop.
Do I have to live on the property to rent out an ADU in Kent?
No. HB 1337 bars cities and counties from requiring the owner to live on the property or in the ADU.
Check your address in 3D · Washington's ADU law, HB 1337
General information from public sources, not legal advice. Codes change and cities differ — confirm with your permit office before you design or build.