January 22, 2026865March 3, 20263315

I, Bernard Dean, Chief Clerk of the House of Representatives of the State of Washington, do hereby certify that the attached is ENGROSSED HOUSE BILL 1345 as passed by the House of Representatives and the Senate on the dates hereon set forth.

Chief Clerk

Secretary of State

State of Washington

EHB 1345.PLENGROSSED HOUSE BILL 1345Passed Legislature2026 Regular Session69th Legislature2025 Regular SessionRepresentatives Low, Peterson, Tharinger, Nance, and GregersonRead first time 01/16/25.Referred to Committee on Housing.Establishing limitations on detached accessory dwelling units outside of urban growth areas. AN ACT Relating to establishing limitations on detached accessory dwelling units outside of urban growth areas; amending RCW 36.70A.696; and adding a new section to chapter 36.70A RCW. Sec. 1. A new section is added to chapter 36.70A RCW to read as follows:

(1) Counties that are required or choose to plan under this chapter may allow detached accessory dwelling units outside of urban growth areas if the county meets the requirements in subsections (2) and (3) of this section, and such detached accessory dwelling units are subject to development regulations that include the following limitations:

(a) No parcel may have more than one accessory dwelling unit, whether attached or detached;

(b) The detached accessory dwelling unit must be subject to the water supply requirements of RCW 19.27.097 and any groundwater mitigation requirements adopted by the county or department of ecology;

(c) The combined water withdrawal for the detached accessory dwelling unit, the principal unit, and any other domestic uses on the parcel may not exceed the use limitations in RCW 90.44.050 for domestic use;

(d) Withdrawals of water by each dwelling unit on the parcel must be metered;

(e) The applicant must provide documentation that the existing or proposed sewage or septic system is capable of handling the additional demand placed upon it by the detached accessory dwelling unit;

(f) The gross floor area of the detached accessory dwelling unit may not exceed the gross floor area of what could be authorized by the county as an expansion of the principal unit to create an attached accessory dwelling unit; however, in no case may the gross floor area be greater than 1,296 square feet. Floor areas exclude garages, porches, and unfinished basements;

(g) The detached accessory dwelling unit must utilize the same driveway or other means of ingress and egress as the principal unit;

(h) The detached accessory dwelling unit must be sited within 150 feet of the principal unit;

(i) The detached accessory dwelling unit may be the existing principal unit if the existing principal unit meets the requirements of this subsection, is a single-family dwelling unit, and a new principal unit that is a single-family dwelling unit is constructed on the same parcel;

(j) The detached accessory dwelling unit must not be allowed on nonconforming lots under one acre; and

(k) A parcel may not be subdivided for the purposes of avoiding the limits on development regulations described in this subsection.

(2) In addition to the requirements in subsections (1) and (3) of this section, counties that allow detached accessory dwelling units outside of urban growth areas must have the following code enforcement measures in place:

(a) A voluntary county code compliance process through which the owner of an unpermitted detached accessory dwelling unit may bring the unpermitted detached accessory dwelling unit into compliance with applicable regulations. In such a case, a permit penalty of at least double the normal permit fee must be applied;

(b) Owners who do not seek voluntary compliance and are found to have constructed or placed a detached accessory dwelling unit without all required permits must be subject to a civil infraction of at least $1,000 and must be required to remove the detached accessory dwelling unit or ensure that it meets all existing development regulations, if applicable. A penalty of at least triple the normal permit fee must be applied if the accessory dwelling unit remains and meets all existing development regulations; and

(c) Any owner who does not seek voluntary compliance and has received a civil infraction for constructing or placing an accessory dwelling unit without all required permits must be prohibited from receiving any permits for the placement or construction of new accessory dwelling units for a period of at least three years.

(3) In addition to the requirements in subsections (1) and (2) of this section, counties that allow detached accessory dwelling units outside of urban growth areas must take the following actions to account for detached accessory dwelling unit development:

(a) The county must track and annually report to the department the number of detached accessory dwelling unit permits completed;

(b) Utilizing the data collected and reported in (a) of this subsection, the county must update its comprehensive land use plan during its next required review and all subsequent reviews required under RCW 36.70A.130(5) to properly account for the number of detached accessory dwelling units completed since the effective date of this section and the projected development over the next 20-year planning period so that the housing units will not exceed the underlying densities for the comprehensive plan designations and zones outside of urban growth areas;

(c) The county must limit future amendments to its comprehensive land use plan under (b) of this subsection such that these amendments may not occur more than once every five years; and

(d) The county must include the following limits on population growth targets in its comprehensive plan:

(i) If the county is a rural county as defined in RCW 43.160.020, the county may allocate no more than 10 percent of its rural population target to detached accessory dwelling units; and

(ii) If the county is not a rural county as defined in RCW 43.160.020, the county may allocate no more than seven percent of its rural population target to detached accessory dwelling units.

(4) Subsection (1) of this section is in addition to other county authority enumerated in this chapter and does not:

(a) Affect or modify the validity of any county ordinance authorizing accessory dwelling units adopted prior to the effective date of this section;

(b) Exclude other means of authorizing accessory dwelling units in urban or rural areas, if consistent with this section; or

(c) Exclude other innovative techniques under RCW 36.70A.070(5)(b), 36.70A.090, or 36.70A.177, if consistent with this section.

 Sec. 2. RCW 36.70A.696 and 2023 c 334 s 2 are each amended to read as follows:Accessory dwelling units—Definitions.

The definitions in this section apply throughout RCW 36.70A.697, 36.70A.698, 36.70A.680, and 36.70A.681, and section 1 of this act unless the context clearly requires otherwise.

(1) "Accessory dwelling unit" means a dwelling unit located on the same lot as a single-family housing unit, duplex, triplex, townhome, or other housing unit.

(2) "Attached accessory dwelling unit" means an accessory dwelling unit located within or attached to a single-family housing unit, duplex, triplex, townhome, or other housing unit.

(3) "City" means any city, code city, and town located in a county planning under RCW 36.70A.040.

(4) "County" means any county planning under RCW 36.70A.040.

(5) "Detached accessory dwelling unit" means an accessory dwelling unit that consists partly or entirely of a building that is separate and detached from a single-family housing unit, duplex, triplex, townhome, or other housing unit and is on the same property.

(6) "Dwelling unit" means a residential living unit that provides complete independent living facilities for one or more persons and that includes permanent provisions for living, sleeping, eating, cooking, and sanitation.

(7) "Gross floor area" means the interior habitable area of a dwelling unit including basements and attics but not including a garage or accessory structure.

(8) "Major transit stop" means:

(a) A stop on a high capacity transportation system funded or expanded under the provisions of chapter 81.104 RCW;

(b) Commuter rail stops;

(c) Stops on rail or fixed guideway systems, including transitways;

(d) Stops on bus rapid transit routes or routes that run on high occupancy vehicle lanes; or

(e) Stops for a bus or other transit mode providing actual fixed route service at intervals of at least fifteen minutes for at least five hours during the peak hours of operation on weekdays.

(9) "Owner" means any person who has at least 50 percent ownership in a property on which an accessory dwelling unit is located.

(10) "Principal unit" means the single-family housing unit, duplex, triplex, townhome, or other housing unit located on the same lot as an accessory dwelling unit.

(11) "Short-term rental" means a lodging use, that is not a hotel or motel or bed and breakfast, in which a dwelling unit, or portion thereof, is offered or provided to a guest by a short-term rental operator for a fee for fewer than 30 consecutive nights.

2023 c 334 s 2; 2021 c 306 s 2; 2020 c 217 s 2. Findings—Intent—2023 c 334: See note following RCW 36.70A.680. Findings—Intent—2020 c 217: "(1) The legislature makes the following findings:(a) Washington state is experiencing a housing affordability crisis. Many communities across the state are in need of more housing for renters, across the income spectrum. Accessory dwelling units are frequently rented at below market rate, providing additional affordable housing options for renters.(b) Accessory dwelling units are often occupied by tenants who pay no rent at all; among these tenants are grandparents, adult children, family members with disabilities, friends going through life transitions, and community members in need. Accessory dwelling units meet the needs of these people who might otherwise require scarce subsidized housing space and resources.(c) Accessory dwelling units can meet the needs of Washington's growing senior population, making it possible for this population to age in their communities by offering senior-friendly housing, which prioritizes physical accessibility, in walkable communities near amenities essential to successful aging in place, including transit and grocery stores, without requiring costly renovations of existing housing stock.(d) Homeowners who add an accessory dwelling unit may benefit from added income and an increased sense of security.(e) Siting accessory dwelling units near transit hubs and near public amenities can help to reduce greenhouse gas emissions by increasing walkability, shortening household commutes, and limiting sprawl.(2) The legislature intends to promote and encourage the creation of accessory dwelling units as a means to address the need for additional affordable housing options." [2020 c 217 s 1.]