Accessory Structures in Tacoma, WA: What Residents Actually Need to Know

If you live in Tacoma or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. Tacoma has 9 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

Tiny Homes

Tacoma is one of Washington's most tiny-home-friendly cities. Tiny houses on a permanent foundation 400 square feet or less are permitted under IRC Appendix Q, adopted statewide in Washington effective July 1, 2021, and applied in Tacoma through TMC 2.02. Tiny homes are most commonly permitted as Detached Accessory Dwelling Units (DADUs) under TMC 13.06.150, with the Home In Tacoma zoning package effective February 1, 2025 expanding allowed locations.

Key details: Building Code: TMC 2.02 + IRC Appendix Q. Appendix Q Effective: July 1, 2021 (statewide). DADU Code: TMC 13.06.150. DADU Side Setback: 5 ft (8 ft if entry faces side). DADU Rear Setback: 15 ft (0 ft from alley).

Placing a tiny home as a permanent dwelling without a building permit, occupying a tiny house on wheels as a permanent residence on a residential lot, or violating ADU setback or size limits can trigger code enforcement under TMC 2.02 and 13.06.150, a stop-work order, and revocation of any related occupancy approval. Confirm penalty amounts with PDS at 253-591-5030.

If you are coming from a city with tighter rules, you will find Tacoma gives residents more flexibility on tiny homes.

Carport Rules

Tacoma treats carports as detached accessory structures under TMC Title 13.06 (Land Use Regulatory Code) and Title 2.02 (Building Code, adopting the 2018 IRC). A building permit is required for any new accessory structure 200 square feet or larger. Where vehicular access is not from an alley or side street, a garage or carport must be set back at least 5 feet behind the front facade of the house.

Key details: Code: TMC 13.06, TMC 2.02. Permit Threshold: 200+ sq ft. Max Height: 15 ft. Max Combined Size: 85% footprint / 15% lot / 1,000 sf. Front-Access Setback: 5 ft behind front facade.

Building a carport without a required permit, exceeding the 15-foot height, placing the carport in front of the main dwelling, or violating the 5-foot front-facade setback can trigger code enforcement under TMC 2.02 and 13.06 and a stop-work order from PDS. Confirm penalty amounts with Planning and Development Services at 253-591-5030.

ADU Permits

Tacoma permits attached (AADU) and detached (DADU) accessory dwelling units ministerially under Tacoma Municipal Code 13.06.150. Washington HB 1337 (2023, codified at RCW 36.70A.681-696) requires Tacoma to allow up to two ADUs on every residential lot. Permits are issued by Planning and Development Services (PDS), and review is a Type I administrative process — no public hearing, no design review.

Key details: Code Section: TMC 13.06.150. ADUs Per Lot: Up to 2 (HB 1337). Review Type: Type I administrative. Decision Window: 60 days (RCW 36.70B.080). Max DADU Size: 1,000 sq ft or 85% of primary.

Constructing an ADU without permits triggers a PDS Notice of Violation under TMC 2.02 and 13.06, a stop-work order, and double permit fees on legalization. TMC 1.82 sets civil infraction penalties; continued violation may result in monetary penalties accruing daily and a recorded property lien. Confirm specific penalty amounts with Planning and Development Services at 253-591-5030.

If you are coming from a city with tighter rules, you will find Tacoma gives residents more flexibility on adu permits.

ADU Impact Fees

Under RCW 36.70A.681(1)(g) (HB 1337), Tacoma may not charge impact fees on ADUs under 1,000 square feet, and impact fees on ADUs 1,000 sq ft and over are capped at 50% of the fee imposed on the primary dwelling. Standard PDS permit fees, TPU water/sewer capacity charges, and Pierce County school impact fees still apply where authorized.

Key details: Under 1,000 sq ft: No impact fees (RCW 36.70A.681). 1,000+ sq ft: Capped at 50% of primary dwelling. Permit Fees: ~$4-10K typical. TPU Capacity Charges: Apply (not impact fees). School Fees: Subject to HB 1337 cap.

Failure to pay TPU general facility charges or school impact fees blocks permit issuance and final inspection. Unpaid fees become a lien on the property. A city demand for a prohibited ADU impact fee may be challenged under RCW 36.70A.681 — the Washington Growth Management Hearings Board has jurisdiction. Confirm specific penalty amounts with PDS at 253-591-5030.

Tacoma is more permissive than most cities when it comes to adu impact fees. That said, there are still limits.

ADU Rental Restrictions

Tacoma allows long-term rental of ADUs without restriction. Short-term rentals (stays under 30 days) of ADUs require a Tacoma Business License and, where the property has both a main dwelling and an ADU, only one of the two units may be used as a short-term rental at any given time. RCW 36.70A.681 prohibits Tacoma from outright banning ADU rentals.

Key details: Long-Term Rental: Allowed; rental license required. STR (Under 30 Days): Business license required. Both Units as STR: Prohibited (only one). 3+ Rooms STR: Transient Accommodation License. Combined Lodging Tax: ~19.5%.

Operating an STR without a business license violates TMC 6A.10 — civil penalties apply per occurrence. Renting both the primary dwelling and the ADU short-term simultaneously violates TMC 13.06.150 and is subject to PDS code enforcement. Lodging tax evasion is referred to the Washington Department of Revenue. Confirm specific penalty amounts with Tacoma Tax and License at 253-591-5252.

ADU Owner Occupancy

Tacoma does not require owner-occupancy for ADUs. Washington HB 1337 (codified at RCW 36.70A.696) prohibits all Washington cities from imposing owner-occupancy on ADUs permitted on or after July 23, 2023. TMC 13.06.150 has been updated to remove any owner-occupancy condition. No deed restriction is required.

Key details: Owner-Occupancy: Not required. State Law: RCW 36.70A.696. Code Section: TMC 13.06.150. Deed Restriction: None required. Rental License: Required (TMC 6A.30).

There is no penalty for non-owner-occupancy of an ADU itself. Failure to obtain a Tacoma rental business license under TMC 6A.30 or to comply with the Rental Housing Code under TMC 1.95 can result in administrative citations. Confirm specific penalty amounts with Tacoma Tax and License at 253-591-5252 and with Planning and Development Services at 253-591-5030.

Tacoma is more permissive than most cities when it comes to adu owner occupancy. That said, there are still limits.

ADU Rules

Tacoma allows two ADUs per lot in zoning districts that permit residential development. Both attached and detached ADUs (DADUs) are permitted. Living area is limited to 1,000 square feet. No parking is required for ADUs. Tacoma offers pre-approved DADU plans.

Key details: Allowed: 2 ADUs per lot. Max Size: 1,000 sq ft living area. Parking: Not required. Owner Occupancy: Not required (HB 1337). Pre-Approved Plans: Available for DADUs.

Unpermitted ADUs face code enforcement. Tacoma encourages legalization of existing unpermitted ADUs through its permitting program.

Shed Rules

Tacoma allows sheds and accessory structures on residential property. Small structures under 200 square feet generally do not require a building permit. Sheds must meet setback requirements and cannot be used for habitation.

Key details: No Permit: Under 200 sq ft, one story. Setbacks: Must meet zoning requirements. Use: Storage only, not habitation. Stormwater: May apply for new impervious area.

Sheds violating setbacks or exceeding size limits without permits face code enforcement notices.

If you are coming from a city with tighter rules, you will find Tacoma gives residents more flexibility on shed rules.

Garage Conversions

Tacoma permits garage conversions to living space including ADUs. Washington State's ADU laws (HB 1337) streamline conversions. Building permits are required. No replacement parking is needed when converting a garage to an ADU.

Key details: Permit: Building permit required. Parking: No replacement required for ADU conversion. Ceiling Height: 7 feet minimum. State Law: HB 1337 streamlines conversions. Energy Code: Must meet current requirements.

Unpermitted conversions require retroactive permitting. Non-compliant spaces must be corrected to meet habitability standards.

The Bottom Line

Compared to many U.S. cities, Tacoma gives residents more room on accessory structures. 5 of the 9 rules here are rated permissive. But permissive does not mean unregulated. There are still requirements, and the city does enforce them when violations are reported.

All of the above reflects Tacoma's municipal code as of our last review. If you need specifics on fines, exemptions, or filing requirements, the detailed ordinance pages linked above have the full breakdown.