ADU Rules in Tacoma, WA (2026)
ADU rules, permit requirements, size limits, and fees for Tacoma, WA. Source-cited from official municipal code.
Yes, ADUs are allowed in Tacoma, WA.
Tacoma, WA permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. State and local law actively preempts local restrictions, making ADU approval a streamlined ministerial process. In Tacoma, the City of Tacoma Planning and Development Services — Building handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Tacoma.
ADU Size Limits
ADU Size Limits in Tacoma: Detached ADU: up to 1000 sq ft (max height: 24 feet). Attached ADU: 1000 sq ft. Washington does not use the California JADU concept. Tacoma allows detached and attached ADUs per TMC Chapter 13.06 and Washington HB 1337 requirements. Up to 2 ADUs permitted per lot. ADU maximum size is 1,000 sqft or 60% of primary dwelling floor area, whichever is smaller, in standard single-family zones.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 1000 sq ft | 24 feet |
| Attached ADU | 1000 sq ft | Same as primary dwelling height limit per zone |
Permit Fees
ADU Permit Fees in Tacoma: Plan check fee: $200–$900. Building permit fee: Based on construction value — typically $500–$2,500. Impact fees: Varies — Tacoma charges utility connection and possibly transportation fees. School fees: None or N/A. Total estimated permit cost: $1,000–$5,000 total fees. Tacoma's ADU fees are lower than Seattle's but higher than Spokane's. Tacoma Public Utilities (TPU) connection fees for electric service; Pierce County for water/wastewater in some areas. Contact Tacoma Planning for current fee schedule.
| Fee Type | Amount |
|---|---|
| Plan Check | $200–$900 |
| Building Permit | Based on construction value — typically $500–$2,500 |
| Impact Fees | Varies — Tacoma charges utility connection and possibly transportation fees |
| School Fees | None |
| Total Estimate | $1,000–$5,000 total fees |
Permit Timeline
Tacoma ADU Permit Timeline: Tacoma Planning and Development Services: plan review typically 3-6 weeks. Tacoma processes ADU permits ministerially per HB 1337 requirements. Construction 4-10 months. Apply through the City of Tacoma Planning and Development Services — Building online permit portal. Phone: (253) 591-5030.
Setback Requirements
ADU Setback Requirements in Tacoma: Front setback: Same as zone standard. Side setback: 5 feet. Rear setback: 5 feet. Detached ADU setbacks: minimum 5 ft from side and rear property lines per TMC Chapter 13.06 and HB 1337. Front setback follows zone standard. Tacoma lots along alleys (common in older neighborhoods like Proctor, North End) may allow ADUs near the alley.
Parking Requirements
Parking Requirements: No additional parking required for ADUs within 0.25 miles of a major transit stop per Washington HB 1337. Tacoma operates Sound Transit Link Light Rail, Pacific Avenue BRT, and Pierce Transit bus service — transit proximity waiver applies to many neighborhoods. 1 space otherwise.
Restrictions & Requirements
- ADU must be on same lot as primary residence
- Up to 2 ADUs allowed per lot per Washington HB 1337
- ADU cannot be sold separately from the primary lot
- Must comply with TMC Chapter 13.06 setback and coverage standards
- JBLM proximity: some areas near the base may have noise overlay zones — check with Tacoma Planning
How Many ADUs Are Allowed?
Number of ADUs Allowed in Tacoma: Single-family lots: 2 ADUs per single-family lot per Washington HB 1337. Multifamily properties: Subject to zone density provisions. Washington HB 1337 requires at least 2 ADUs per single-family lot. Tacoma has complied with state law.
Single-Family Lots
2 ADUs per single-family lot per Washington HB 1337
Multifamily Properties
Subject to zone density provisions
State Law & Preemption
State Preemption: Washington House Bill 1337 (2023) requires all Washington cities and counties to allow at least 2 ADUs per single-family residential lot by-right. Removes owner-occupancy requirements statewide. Limits off-street parking requirements for ADUs within 0.25 miles of a major transit stop. Effective July 23, 2023. Tacoma has updated its Municipal Code to comply with HB 1337. Washington does not use the California JADU concept.
Historic District Considerations
Historic District Requirements: Tacoma has 5 historic districts where additional design review may be required for ADU construction. Design review approval is required before obtaining a building permit for properties in historic overlay zones. Tacoma has several significant historic districts including the Stadium District (surrounding Stadium High School, a former château turned school), the North Slope Historic District, Old Town Historic District, and the Broadway Historic District. Tacoma was once called 'The City of Destiny' for its expected railroad dominance — much of this era's architecture is preserved in historic districts. Certificate of Appropriateness required for exterior changes in designated zones. The Tacoma Landmarks Preservation Commission oversees historic review. Look up historic district boundaries at: https://www.cityoftacoma.org/government/city_departments/planning_and_development_services/land_use_and_planning/historic_preservation
Frequently Asked Questions
Can I build an ADU in Tacoma?
Yes. Tacoma, WA allows accessory dwelling units. On a single-family lot you can build 2 ADUs per single-family lot per Washington HB 1337.
How big can an ADU be in Tacoma?
The maximum size for a detached ADU in Tacoma is 1,000 square feet.
How long does it take to get an ADU permit in Tacoma?
The typical ADU permit timeline in Tacoma is Tacoma Planning and Development Services: plan review typically 3-6 weeks. Tacoma processes ADU permits ministerially per HB 1337 requirements. Construction 4-10 months.. Total estimated permit fees are $1,000–$5,000 total fees.
Do I need extra parking for an ADU in Tacoma?
No, Tacoma does not require additional parking for ADUs.
Do I have to live on-site to have an ADU in Tacoma?
No, owner-occupancy is not required for ADUs in Tacoma.
Source: Tacoma Municipal Code Chapter 13.06 — Land Use Regulatory Code; Washington HB 1337 (2023). Last verified April 6, 2026. View source