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Accessory Dwelling Units

ADU drawing

Accessory Dwelling Units (ADUs) offer a unique housing opportunity that aligns with Kirkland’s community goals of preserving neighborhood character, increasing housing affordability, create a wider range of housing options within the community, enable seniors to stay near family as they age, and facilitate better use of the existing housing fabric within our neighborhoods.

On March 17, 2020, City Council approved O-4715 and O-4716 that updated existing ADU regulations.  Following this, the Houghton Community Council voted unanimously to approve both ordinances.

ADU Regulations – Summary Table 


Attached ADU (AADU) 

Accessory dwelling units that are added to or included within the principal unit. 

Detached ADU (DADU) 

Accessory dwelling units that are located in a detached structure. 


Maximum size of 1,200 square feet.1 

FAR exemption for DADUs 

Portion (500-800 sq. ft.) of square footage of DADU is exempt from FAR if located 10 feet from and behind principal unit (see KZC 115.42).  

Number of ADUs 

Two – both may be either attached or detached.2

Applicants planning on two attached ADUs should contact the Planning and Building Department at (425) 587-3600 for additional Building Code assistance.


Must conform to development standards, i.e. lot coverage, setbacks, etc., for single-family dwellings in the applicable use zone. 1, 3, 4, 5 

Owner Occupancy 

Not required 


One ADU: none 

Two ADUs: one required, with exceptions (available street parking within 600 feet or property is located within ½ mile of frequent transit). 

Separate ownership 

Allowed for DADUs.  DADUs may not be subdivided from principle unit.6

ADUs on lots created through small lot and historic subdivisions 

Allowed.  DADUs on history lots must be located behind the historic residence. 

Required yards (setbacks): 

Same as underlying zoning.  DADUs may be located within 5 feet of an alley.  DADUs without alley access may be located no closer than 5 feet from the rear property line as long as the portion of the DADU in the reduced setback is no taller than 15 feet. 

1 See additional size limitations for accessory structures in Kirkland Zoning Code (KZC) Section 115.08

2 Any property within the Residential-L Shoreline Environment is only allowed one (1) ADU 

3 Except as modified by KZC 115.42 and KZC 115.115.3.o. 

4 DADUs located on lots approved using the historic preservation subdivision regulations must be located behind the historic residence.   

5 DADUs shall be located landward of the principal residence on any property located within the Residential-L and M/H Shoreline Environments pursuant to KZC 83.200.3. 

6 Separate ownership is not allowed on properties within the Residential-L Shoreline Environment.  ADUs within M/H Shoreline Environment may have separate ownership subject to a Substantial Development Permit.   Any ADU created within the M/H Shoreline Environment under separate ownership will require a pedestrian pathway meeting the requirements of KZC 83.420.

Can I build an ADU on my property?

Accessory Dwelling Units are allowed subordinate to a principle unit, including units approved through the City’s Cottage, Carriage and Two/Three-Unit Homes regulations.  ADUs must meet the underlying zoning including, but not limited to, setbacks, lot coverage, height, and floor area ratio as described in the zoning code.  Key regulations include:

  • A property’s underlying zoning, which includes regulations like allowed uses, setbacks, lot coverage, height, etc.
  • Accessory structure regulations (in addition to Accessory Dwelling Unit regulations).

The Kirkland Zoning Code may be found online herelinks to external site.

What is my zone?

You may find your property’s zoning two ways:

Kirkland’s Zoning Map:  This is a standalone zoning map that describes the zoning districts within Kirkland’s City limits. 

Kirkland’s Geographic Information System (GIS) maplinks to external site.  This map provides links to a property’s zoning and a useful property report that includes information on a property’s size, sewer district, water district, and mapped environmental areas that may be affecting the property.

The City provides a Public GIS browser tutorial Document (PDF) to learn how to use this interactive map.

You may also ask City Staff for assistance by submitting questions through Our Kirkland portal.

 How do I apply for an ADU permit?

Application forms, instructions, and fees may be found at Development Service Center’s All Forms, Publications, & Fees webpage. 

All permits can be submitted through MyBuildingPermitlinks to external site.

For assistance contact:

  • Online:  Submit your question through the Our Kirkland portal.
  • Planning and Building:  (425) 587-3600
  • Public Works:  (425) 587-3800
  • Fire:  (425) 587-3661

Are there useful resources I should consider before I design my ADU?

If you are considering developing an ADU here are some useful links to resources outside of the City.  While these are complementary and useful resources some information may not be consistent with City of Kirkland’s development regulations and policies for ADUs.  You should be familiar with City’s ordinances and regulations prior to submitting for a permit.

AARP’s All About Accessory Dwelling Unitslinks to external site provides A Step by Step Guide to Design Development, links to videos, articles, and additional links to web resources.

A Regional Coalition for Housing (ARCH):  Provides an ADU webpagelinks to external site that features information on how to select an architect, contractor, and provides an overview on lending assistance.









    Planning & Building Department
    123 5th Avenue, Kirkland WA 98033

    General Inquiries:
    Contact us via the: 
    Our Kirkland Customer Service Portal
    T. 425.587.3600 | F. 425.587.3232