Building an ADU or backyard cottage in Kirkland

What you can build in Kirkland

Kirkland's ADU rules are in Kirkland Zoning Code (KZC) 115.07, summarized on the city's ADU Regulations page. You can have two ADUs, and "both may be either attached or detached." Kirkland calls a unit added to or inside the house an attached ADU (AADU), and one in a separate building a detached ADU (DADU).

If you plan two attached ADUs, the city asks you to call the Planning and Building Department at 425-587-3600 for building code help. Properties in the Residential-L Shoreline Environment are allowed only one ADU.

For the state rules, see our Washington ADU law page. For areas outside city limits, see our King County page. [1]

Size, setbacks and height

An ADU can be up to 1,200 square feet. The Planning Director may approve more square footage if an attached ADU is on a single floor inside the existing house.

ADUs "must conform to development standards, i.e. floor area ratio, lot coverage, setbacks, etc., that regulate the primary dwelling unit," with some exceptions in the zoning code. On shoreline properties in the Residential-L and M/H Shoreline Environments, a DADU must sit landward of the house.

State law says a city can't cap ADU size below 1,000 square feet or roof height below 24 feet (or below the house's limit, if lower). Check your lot's zone and limits with a city planner before you design. [1][2][4]

Parking

No off-street parking is required within one-half mile of a major transit stop. The city says its current major transit stop is the Stride (I-405) bus rapid transit station, with future stops along King County Metro's RapidRide K Line.

Elsewhere, one off-street space is required for the first ADU, unless on-street parking is available within 600 feet or the property is within a half mile of frequent transit (service every 15 minutes during commute hours).

A 2025 state law, RCW 35.21.994, says a city "may not require any minimum parking requirements" for "Residences under 1,200 square feet," with some exceptions. It doesn't apply to cities of 30,000 people or fewer. Kirkland has 98,860 people, according to the state's April 1, 2026 estimate, so it is in the group of cities of 50,000 or more, which must put the law in place within 18 months of July 27, 2025 (that is, by January 27, 2027). The city's ADU page still lists the one-space rule above, so ask the city which parking rule applies to your ADU. [1][5][6]

Fees and impact fees

Kirkland's development fees rose 2.7 percent on January 1, 2026. Park, fire and transportation impact fees for ADUs are being phased in over three years starting July 2025. The city says "Complete ADU building permit applications received on or after July 1, 2026 will be charged impact fees," and "ADUs 800 square feet or less in size will continue to be exempt."

Kirkland's July 2026 impact fee notice lists these rates for an ADU over 800 square feet, for applications deemed complete from July 1 to December 31, 2026:

• Park impact fee: $2.59 per square foot
• Transportation impact fee: $2.26 per square foot
• Fire impact fee: $0.38 per square foot
• School impact fee: $0 in the city's ADU examples

For an 801-square-foot ADU, that comes to about $4,190. The rates rise again on January 1 and July 1, 2027. State law caps ADU impact fees at 50 percent of the impact fees for the main house. Kirkland also has water, sewer and stormwater capital facility charges; ask Public Works at 425-587-3800 which charges apply to your ADU. Current fee schedules are on the city's forms, publications and fees page. For budgeting, see our ADU cost guide. [4][7][8][9]

Pre-approved DADU plans

Kirkland's gallery of pre-approved ADU plans has detached designs by local architects, from about 476 to 1,132 square feet. You contact the designer and pay a fee set by the designer of up to $1,000 to use the plan. You don't submit the building plans themselves; city staff add the registered plan set to your permit.

A pre-approved plan can get expedited review, but not if the lot is in shoreline jurisdiction, a geologic or seismic hazard area, or needs critical area review. To qualify, the project also must:

• Add or replace less than 2,000 square feet of impervious area
• Connect to an available public storm system, and to public sewer or the house's existing side sewer
• Need no new water meter or service upgrade
• Add no new driveway, parking area or garage, and not change the curb cut or sidewalk

The city says pre-approved plans can be ready for permit approval in "as little as a few weeks." [9][10][11]

Selling or splitting off an ADU

An ADU "may be segregated in ownership from the primary dwelling unit," except on properties in the Residential-L Shoreline Environment. In the M/H Shoreline Environment, separate ownership needs a Substantial Development Permit. A DADU may also be placed on its own "unit lot" through a unit lot subdivision.

The city notes that making an ADU legally separable, such as by condo-izing it, takes upfront legal and permitting steps. [1][12]

Renting it out

Renting out any unit in Kirkland requires a business license. You also need a State of Washington business license.

Kirkland's short-term rental rules (stays under 30 days) apply mainly to single-family homes. You can rent a registered ADU short-term after getting both licenses. Whether you can do so without limit, or for no more than 120 days a year, depends on whether the owner or an authorized agent lives on the property as a primary residence continuously or at least 245 days a year. A property manager living within 15 miles must be named for days when neither is there. For business license questions, call 425-587-3145. [9][13][14]

Permit steps in Kirkland

1. Check what's possible on your lot

   Look at zoning, lot size, slopes, streams, trees, setbacks and height limits. Call a city planner at 425-587-3600 or ask through Our Kirkland. Projects near lakes, streams, slopes or wetlands may need extra review. [2][3]

2. Choose a pre-approved plan or a custom design

   Pick a detached design from the pre-approved plan gallery and license it from the designer, or hire a designer for custom plans. [9][10]

3. Set up your permit account

   Create an account on MyBuildingPermit.com, where you submit plans, track progress and schedule inspections. For a pre-approved DADU, choose Kirkland, Building, New Construction, Pre-Approved Detached Accessory Dwelling Unit. [3][9]

4. Prepare and submit your documents

   For a pre-approved DADU, submit a site plan with the plan Registration ID, a Supplemental Building Information Form, an ADU Registration Application and a plumbing worksheet, plus a survey, geotechnical report, rodent abatement letter, fire sprinkler permit or demolition permit when needed. The ADU registration is recorded with the King County Recorder's Office, and you pay the recording fee before the certificate of occupancy. [3][9]

5. Build and pass inspections

   Once the permit is approved, build and schedule inspections on MyBuildingPermit.com. [3]

6. Final inspection and move-in

   After the final inspection you receive a certificate of occupancy. If you will rent the unit, get a business license and follow landlord and rental rules. [3][13]

Pre-approved and sample plans

• Pre-Approved Detached ADU Plans

  City-reviewed DADU designs you license from the designer for up to $1,000; projects that meet site and utility criteria qualify for expedited review. [9][10]

Who to call

• Kirkland Planning and Building Department

  ADU zoning and building code questions, pre-approved plans

  425-587-3600

  123 5th Avenue, Kirkland, WA 98033

  [2][9]

• Kirkland Fire Department

  Fire code questions for ADUs

  425-587-3661

  [9]

• Kirkland Public Works Department

  Utility fees and public improvement requirements

  425-587-3800

  [9]

• Kirkland Business Licensing

  Business licenses for rental units, including short-term rentals

  425-587-3145

  [9][14]

Questions people ask