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Tacoma, WA Accessory Structures: ADU Rules (2026)

Some Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

ADU rules in Tacoma, WA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.

Key Facts

ADUs per lot: 2 allowed
Habitable area cap: 1,000 sq ft
Parking: None required
ADU-specific height limit: None (follows housing type)

ADU Eligibility Quick-Check

An Accessory Dwelling Unit (ADU) is a smaller, independent living unit on the same lot as a single-family home: converted garages, detached cottages, basement or attic conversions, and attached additions all qualify. Most states have streamlined ADU permitting since 2020, but local rules still control size, height, and setback.

Is your lot zoned single-family or multi-family residential?
Does your lot have at least 1,200 sq ft of buildable space?
Is your existing home owner-occupied (in most states this is not required, but some require it for ADU permits)?
Will the ADU stay under your state's size cap (commonly 850-1,200 sq ft for detached)?
Can you provide one off-street parking space (waived in many states within 0.5 mi of transit)?

If you answered 'yes' to most of these, you likely qualify in Washington under recent ADU streamlining laws. The Tacoma, WA rules below cover local size, height, and setback requirements.

Summary

Tacoma allows two accessory dwelling units per residential lot, each capped at 1,000 square feet of habitable area, with no parking required.

Number. Two ADUs shall be allowed per residential lot as a subordinate use in conjunction with any new or existing residential development in the City of Tacoma. … The habitable area of ADUs, excluding any garage area and other non-living areas, shall be limited to a maximum of 1,000 square feet. … No off-street parking is required for ADUs.

Source: Tacoma ADU Tip SheetView official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4946110; v22 updated 2026-07-28).

Full Breakdown

Title 13's ADU standards, TMC § 13.06.080A, let a property owner build two ADUs per residential lot in any Residential Zoning District, attached or detached, on lots of any size or width, subject to setback, height, and amenity-space rules for the underlying housing type. Habitable area, excluding garage space, is capped at 1,000 square feet, and no off-street parking is required. Washington's 2023 middle-housing law (HB 1110) and ADU law (HB 1337) require cities to permit ADUs on generous terms statewide; Tacoma's two-ADU allowance implements, and exceeds, that state floor.

Violations & Fines

Building without a permit or exceeding the 1,000-square-foot habitable-area cap can result in a stop-work order and code enforcement action under Title 13's ADU standards.

Frequently Asked Questions

How many ADUs can I build in Tacoma?

Two per residential lot, attached or detached, under TMC § 13.06.080A.

Is there a size limit?

Yes: habitable area, excluding garage space, is capped at 1,000 square feet.

Sources & Official References

[1]Tacoma Municipal Code — Chapter 13.06, Zoning (eCode360)

Other rules in Tacoma

Fence Regulations: Height LimitsSome Restrictions Shed & Carport RulesSome Restrictions Parking Rules: RV & Boat ParkingSome Restrictions Tiny HomesSome Restrictions Garage ConversionsSome Restrictions Parking Rules: Loading ZonesSome Restrictions Parking Rules: Driveway RulesSome Restrictions Parking Rules: Preferential Parking DistrictsSignificant Restrictions Fence Regulations: Material RestrictionsSignificant Restrictions

All Tacoma rules

How Tacoma compares: Easiest Cities to Build an ADU·Compare Tacoma to another location·View the Washington accessory structures overview

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ADU Rules in Nearby Cities

How other cities in this county handle adu rules.

Lakewood, WA