ADU & backyard cottage rules in Tacoma, WA
Tacoma rewrote its residential zones in 2025. Home in Tacoma, Phase 2 (Tacoma Municipal Code 13.06, effective February 1, 2025) replaced the old single-family districts with three Urban Residential zones, UR-1, UR-2 and UR-3, and most house lots in the city now sit in one of them.
What a zone allows is mostly a matter of floor area, coverage and setbacks. Tacoma limits a building by floor-area ratio instead of a flat size cap: in UR-1, 0.6 of the lot for one or two homes and 0.8 for three or more. Coverage runs from 60% in UR-1 to 70% in UR-3, and the smallest lot is 2,500 sq ft in all three. The table below is exactly what our engine reads.
Density bonuses exist for lots that include an affordable unit, which is why the table shows more than one density figure for each zone. Detached accessory units follow the state floor set by HB 1337 (see the guide linked below); the setbacks and coverage above still decide whether one fits on your lot.
The rules our engine reads for Tacoma
| Zone | Coverage | Height | Smallest lot | Setbacks front / side / rear | Also |
|---|---|---|---|---|---|
| UR-1 | 60% | 35 ft | 2,500 sq ft | 15 ft / 5 ft / 15 ft | one home per 1,500 sq ft of lot; floor area 0.6 of the lot for 1–2 units; 0.8 for 3 or more |
| UR-2 | 65% | 35 ft | 2,500 sq ft | 15 ft / 5 ft / 15 ft | one home per 1,000 sq ft of lot; floor area 0.8 of the lot for 1–2 units; 1.0 for 3 or more |
| UR-3 | 70% | 45 ft | 2,500 sq ft | 10 ft / 5 ft / 10 ft | one home per 750 sq ft of lot; floor area 1 of the lot for 1–2 units; 1.2 for 3 or more |
Rules checked 2026-10-25. Sources: Tacoma Municipal Code 13.06 — Home in Tacoma, Phase 2 (UR zones, effective 2025-02-01).
What this means for your lot
- Find your zone code on your parcel record or Tacoma'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 Tacoma?
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 Tacoma depends on its setbacks and coverage, which are in the table on this page.
How big can an ADU be in Tacoma?
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 Tacoma?
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. The local parking rule is not in our tables yet.
Do I have to live on the property to rent out an ADU in Tacoma?
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.