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][2][3]
Yes, you can build an ADU in Tacoma. A detached ADU can be up to 1,000 sq ft under current Washington and Tacoma zoning rules.
| Allowed Zones | Residential zones (most) |
| Max Size (Detached) | 1,000 sq ft living area |
| Max Size (Attached) | 1,000 sq ft living area |
| Max Size (JADU) | N/A (Washington does not use a separate JADU category) |
| Max Height | 35 feet |
| Max Units | Up to 2 ADUs per lot |
Setback Requirements [1][2][3]
Tacoma requires a rear setback of about 15 ft for a detached ADU, and no additional parking is required. Owner-occupancy is not required — you can rent it out without living on the property.
| Rear Setback | 15 feet (no setback required from an alley) |
| Side Setback | 5 feet (8 feet if the main entrance faces the side property line) |
| Front Setback | Per underlying zone; Confirm with Tacoma Permits |
| Parking Required | Not required (per Washington HB 1337) |
| Owner Occupancy | Not required |
| Min Lot Size | No minimum — allowed on any legally established lot regardless of size or width |
Permit Process & Fees
An ADU permit in Tacoma typically costs $1,800-$2,800 and takes 40-60 days, through a standard permit review.
| 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 [4][5]
Building an ADU in Tacoma typically costs $135,000-$270,000 ($125-$245 per sq ft); a garage conversion runs $65,000-$155,000.
| 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 |
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Rental Income Potential [6][7]
A 2-bedroom ADU in Tacoma rents for around $1,650-$2,300/mo, an estimated 7-9% annual return.
| 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.
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Recent Law Changes
What's Changed Recently
- Washington HB 1337 (effective July 2023): requires cities to allow up to 2 ADUs per lot, at least 1,000 sq ft each, no owner-occupancy (except short-term rentals), and parking limits near major transit
- Washington HB 1345 (signed March 2026, effective June 11, 2026): a county-option law allowing one detached ADU on rural parcels outside urban growth areas (up to 1,296 sq ft) — does not change Tacoma's in-city rules
- Tacoma allows two ADUs per lot, up to 1,000 sq ft each, with no off-street parking required
- Tacoma offers pre-approved (base model) DADU plans — one of the most homeowner-friendly programs in WA
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
ADU Builders in Tacoma
Looking for an ADU builder in Tacoma? ADU projects need a contractor experienced with local zoning, the permit process, and utility connections — not every general contractor has built one. We match Tacoma homeowners with experienced local ADU contractors who provide free, no-obligation quotes. Getting at least three bids typically saves 20-40% on the same scope.
Sources & References
All data on this page is sourced from official government records and verified market data. View our full methodology.
- Accessory Dwelling Units Tip Sheet — Tacoma Permits Planning Department — Accessed 2026-06-28
- Accessory Dwelling Units — Tacoma Permits Planning Department — Accessed 2026-06-28
- Washington HB 1337 (2023) — Washington State Legislature Government Data — Accessed 2026-06-28
- Angi — 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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How much does an ADU cost in Tacoma?
How much can I rent an ADU for in Tacoma?
Do I need parking for an ADU in Tacoma?
How long does it take to get an ADU permit in Tacoma?
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