Can I Build ADU in Tacoma, WA? (2026)
Find out if you can build a adu in Tacoma, WA. Rules, permit requirements, costs, and next steps.
Yes, ADUs are allowed in Tacoma, WA. California state law ensures by-right approval.
An Accessory Dwelling Unit (ADU) is a secondary housing unit on a residential lot — also called a granny flat, in-law suite, or backyard cottage. In Tacoma, WA, ADUs are permitted by right under state law, making them one of the most accessible ways to add housing on your property. ADUs can be detached, attached to the main home, or created by converting an existing garage or accessory structure.
ADU Rules in Tacoma
ADU Rules in Tacoma: Detached ADU max size: 1000 sq ft. Attached ADU max size: 1000. Setbacks: 5 ft side, 5 ft rear. Owner-occupancy: No owner-occupancy requirement per Washington HB 1337, which explicitly removes owner-occupancy requirements statewide effective July 23, 2023.. State preemption applies: WA law requires Tacoma to approve compliant ADUs by right.
Costs & Fees
ADU permits in Tacoma: Total estimated permit cost: $1,000–$5,000 total fees. Contact the City of Tacoma Planning and Development Services — Building for current fee schedule.
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.
Next Steps
Next steps for building an ADU in Tacoma: 1. Review full ADU rules including size limits, setbacks, and parking. 2. Apply for an ADU permit through the City of Tacoma Planning and Development Services — Building at https://permits.cityoftacoma.org/. 3. Hire a licensed contractor familiar with WA ADU requirements.
City of Tacoma Planning and Development Services — Building
Phone: (253) 591-5030
Website: https://www.cityoftacoma.org/government/city_departments/planning_and_development_services
Online Permits: https://permits.cityoftacoma.org/
Frequently Asked Questions
Can I build an ADU on my Tacoma property?
Yes. Washington HB 1337 (2023) requires Tacoma to allow at least 2 ADUs per single-family lot by-right, without owner-occupancy requirements. ADUs are limited to 1,000 sqft. No owner-occupancy requirement. Tacoma has updated its Municipal Code to comply with state law. The permit must be processed ministerially. Contact Tacoma Planning and Development Services for specific requirements.
How does Tacoma's housing market compare to Seattle?
Tacoma's housing is significantly more affordable than Seattle — median home prices are roughly 25-35% lower. Tacoma is in the Seattle-Tacoma-Bellevue MSA and many residents commute to Seattle via Sound Transit's Sounder commuter train or light rail. This makes Tacoma attractive for buyers priced out of Seattle. The downtown has undergone significant revitalization with museums (Museum of Glass, Tacoma Art Museum), restaurants, and the University of Washington Tacoma campus.
What is Joint Base Lewis-McChord and how does it affect Tacoma's housing?
Joint Base Lewis-McChord (JBLM) is a combined Army (Fort Lewis) and Air Force (McChord Air Force Base) installation located adjacent to Tacoma, making it one of the largest military installations on the West Coast. JBLM has approximately 40,000 active duty personnel plus families — creating enormous housing demand in Tacoma and Pierce County. Military housing allowances often support higher rental rates in Tacoma neighborhoods near transit routes to JBLM. For ADU investors, JBLM creates stable rental demand.
Who provides electricity in Tacoma?
Most of Tacoma is served by Tacoma Public Utilities (TPU), a city-owned utility. This distinguishes Tacoma from areas served by Puget Sound Energy. TPU rates are generally competitive and the city-owned structure can be more flexible on solar interconnection. For solar installations, you'll need an electrical permit from Tacoma Planning and an interconnection agreement with TPU. Some Tacoma areas near city limits may be served by Puget Sound Energy — verify your service provider.
What should I know about Tacoma's hillside neighborhoods?
Tacoma has many neighborhoods on hills with views of Puget Sound and Mount Rainier. These hillside neighborhoods (North End, Proctor District, Stadium District) are highly desirable but come with geologically hazardous area designations on many properties. Landslide risk affects some hillside lots — geological reports may be required for building permits near steep slopes. Tree removal near steep slopes requires additional review. The views are spectacular but the slopes require careful due diligence before construction.
Source: City of Tacoma Planning and Development Services — Building — Building Regulations. Last verified April 6, 2026. View source