Tacoma offers reasonable ADU regulations with by-right approval in most residential zones. The city has been increasingly supportive of accessory dwelling units as a housing solution, with streamlined permitting and modest size limits.
Zoning & Size Requirements [1]
| Allowed Zones | Residential zones (most) |
| Max Size (Detached) | 1,100 sq ft |
| Max Size (Attached) | 900 sq ft |
| Max Size (JADU) | 750 sq ft |
| Max Height | 35 feet |
| Max Units | 1 ADU per lot |
Setback Requirements [1]
| Rear Setback | 10 feet |
| Side Setback | 3 feet |
| Front Setback | 15 feet |
| Parking Required | Optional |
| Owner Occupancy | Not required |
| Min Lot Size | 3,500 sq ft |
Permit Process & Fees
| Approval Process | Building permit with streamlined review |
| Review Timeline | 40-60 days |
| Permit Fees | $1,800-$2,800 |
| Impact Fees | $500-$900 |
| Plan Check | 2-3 weeks |
| Pre-Approved Plans | Available for common types |
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Construction Costs [2][3]
| Average Build Cost | $135,000-$270,000 |
| Cost per Sq Ft | $125-$245 |
| Garage Conversion | $65,000-$155,000 |
| Prefab ADU (Installed) | $100,000-$230,000 |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders.
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Rental Income Potential [4][5]
| Avg Rent (1 Bedroom) | $1,300-$1,750/mo |
| Avg Rent (2 Bedroom) | $1,650-$2,300/mo |
| Short-Term Rental | Restricted to primary residence owners |
| Est. Annual ROI | 7-9% annual return |
Explore Prefab ADU Options
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Recent Law Changes
What's Changed Recently
- HB 1337 full implementation (2026): All urban growth areas must allow 2 ADUs per lot
- Seattle eliminated single-family zoning: Up to 4 homes per lot in NR zones
- No owner-occupancy requirement statewide (HB 1337 provision)
- Washington ADU permit fee caps now in effect for units under 1,000 sq ft
Tips for Building an ADU in Tacoma
- Tacoma's lower property costs vs. Seattle create better cash flow potential
- Proximity to Seattle makes it attractive for commuters; strong rental demand
- Streamlined permitting means faster project timelines
- Short-term rental restrictions; focus on long-term tenant base
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Accessory Dwelling Units — Tacoma Permits Planning Department — Accessed 2026-02-24
- HomeAdvisor — ADU Construction Cost Data Market Data — Accessed 2026-02-24
- Angi — Local ADU Contractor Costs Market Data — Accessed 2026-02-24
- Zillow Rental Manager — Market Rent Data Market Data — Accessed 2026-02-24
- HUD Fair Market Rents Government Data — Accessed 2026-02-24
- ADU Tip Sheet — Tacoma Planning Department — Accessed 2026-02-24
- Washington ADU Legislation (HB 1337) Government Data — Accessed 2026-02-24
Frequently Asked Questions
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