Does Yakima County, WA have its own adu rules ordinance?

No. Yakima County, WA does not appear to have a local adu rules ordinance, Washington state law applies instead. The rules summarized on this page come from Revised Code of Washington.

Key Facts Ordinance Text Full Breakdown Violations FAQ Sources More in Yakima County

Yakima County, WA Accessory Structures: ADU Rules (2026)

Few Restrictions

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

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

Key Facts

State Law: HB 1337 / RCW 36.70A.681
How Many: Two ADUs, UGA lots
Minimum Size Cap: At least 1,000 sq ft
Owner-Occupancy: Cannot be required
Parking: None within half-mile transit

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 Yakima County, WA rules below cover local size, height, and setback requirements.

Summary

Washington's HB 1337 (RCW 36.70A.681) requires Yakima County to allow at least two accessory dwelling units on lots within its urban growth areas, cannot cap ADUs below 1,000 square feet, and cannot require owner-occupancy.

City-specific rules exist: Yakima has its own adu rules rules that differ from Yakima County's county-level regulations. If you live in Yakima, check the city-specific page instead.

The city or county may not require the owner of a lot on which there is an accessory dwelling unit to reside in or occupy the accessory dwelling unit or another housing unit on the same lot.

Source: Revised Code of WashingtonView official code

Full Breakdown

HB 1337 (2023), codified at RCW 36.70A.681, directs GMA-planning jurisdictions like Yakima County to allow at least two accessory dwelling units on lots within urban growth areas that permit single-family homes. The county may not set a maximum ADU size below 1,000 square feet, may not require the owner to live on-site, and may not require off-street parking for ADUs within one-half mile walking distance of a major transit stop. Impact fees on an ADU are capped at 50 percent of those on the principal unit. Rural lots outside a UGA follow Yakima County's rural zoning. Any ADU still needs a building permit under the state building code.

Violations & Fines

Building or occupying an ADU without a county building permit is enforced under RCW 19.27 with stop-work orders. County provisions that conflict with RCW 36.70A.681 are unenforceable.

Frequently Asked Questions

Can I build an ADU in unincorporated Yakima County?

On a lot within an urban growth area that allows single-family homes, yes. HB 1337 requires the county to allow at least two ADUs, up to at least 1,000 square feet each.

Do I have to live on the property?

No. Under RCW 36.70A.681 the county cannot require the owner to reside in or occupy the ADU or the main home.

Sources & Official References

[1]Revised Code of Washington

Other rules in Yakima County

Fence Regulations: Height LimitsSome Restrictions Shed & Carport RulesFew Restrictions Tiny HomesSome Restrictions Parking Rules: Loading ZonesSome Restrictions Parking Rules: Driveway RulesSome Restrictions Parking Rules: EV ChargingSome Restrictions Fence Regulations: Retaining WallsSome Restrictions Fire Regulations: Propane StorageSome Restrictions

All Yakima County rules

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

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ADU Rules in Cities Across Yakima County

Yakima, WA