ADU Permits in Tacoma
Rules for detached (DADU) and attached (AADU) accessory dwelling units in Tacoma, Pierce 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 Tacoma 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
Four city base models, from a 300 sq ft studio to two bedrooms over a garage.
Tacoma permit-process facts
ADU permit fees
Set by the Tacoma fee schedule.
Fee scheduleTacoma's ADU land use permit is $1,330 (Table 4). The building permit is a combination building, mechanical and plumbing permit (Table 8-4): 1.31% of the ICC building valuation for new construction, or 2.81% for an ADU built as an addition, with plan review at 45% of that fee, and a site development permit (grading and erosion control) at 65% of the building permit fee with its own plan review at 45%. Table 1 adds the technology (5%), emergency preparedness (5%) and reserve fund (2%) surcharges, and the natural resources program (5%) on building permits. Apply via aca-prod.accela.com/
Review timeline
Typical: 21–60 business days
Measured, detached ADU: half issued within 138 days of application, 80% within 25575 permits, last 12 months. Source: City of Tacoma residential building permits (Accela Permit Data, City of Tacoma open data).
HB 1337 conformance
Tacoma 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 Tacoma’s ADU rules as Kolmo reads them; an address’s own page adds its setbacks, easements and critical-area buffers. Source: tacomapermits.org, last verified 2026-04-29.
ADU permits in Tacoma — FAQ
Does Tacoma allow detached ADUs (DADUs)?
Yes. Washington's HB 1337 (RCW 36.70A.681) requires Tacoma 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 Tacoma?
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)). Tacoma's own maximum may be higher — the per-parcel page shows it with the city's code citation.
How long does ADU permit review take in Tacoma?
Tacoma's ADU permits typically review in 21–60 business days. Pre-approved standard plans (where available) cut this further.
How long does it actually take to get a detached ADU permit in Tacoma?
75 permits issued in the last 12 months: half were issued within 138 days of application and 80% within 255 (over-the-counter and plan-reviewed together; the City's records do not separate them). Measured by Kolmo from City of Tacoma residential building permits (Accela Permit Data, City of Tacoma open data).