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
| 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
| 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
| 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 (installed) |
Finance Your ADU Project
Most ADU projects are funded through HELOCs, construction loans, or cash-out refinancing. Compare rates from top lenders in minutes.
Compare ADU Financing Options →Rental Income Potential
| 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
Prefab ADUs can save 20-40% vs. traditional construction and cut build time in half. Compare top prefab manufacturers.
Compare Prefab ADUs →Recent Law Changes
What's Changed Recently
- 2024: Expanded ADU allowance in most residential zones
- 2023: Streamlined permitting process
- 2024: Increased max detached ADU size from 1,000 to 1,100 sq ft
- 2023: Added JADU provisions in select neighborhoods
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
Frequently Asked Questions
Can I build an ADU in Tacoma?
Yes. ADUs are allowed in Residential zones (most) in Tacoma. The maximum size for a detached ADU is 1,100 sq ft. No owner-occupancy is required.
How much does an ADU cost in Tacoma?
ADU construction in Tacoma typically costs $135,000-$270,000. Garage conversions run $65,000-$155,000, and prefab ADUs cost $100,000-$230,000 (installed).
How much can I rent an ADU for in Tacoma?
Average ADU rents in Tacoma are $1,300-$1,750/mo for a 1-bedroom and $1,650-$2,300/mo for a 2-bedroom unit.
Do I need parking for an ADU in Tacoma?
Optional. Check with Tacoma planning department for the latest Washington ADU parking rules, as many states have relaxed requirements in recent years.
How long does it take to get an ADU permit in Tacoma?
The permit review timeline in Tacoma is 40-60 days. Fees range from $1,800-$2,800.
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