An accessory dwelling unit (ADU) is a habitable living unit that provides the basic requirements of shelter, heating, cooking (a stove and sink), and sanitation (with a toilet and shower), located on the same lot and subordinate to an existing single-family dwelling in size and height. An ADU must have separate water and sewer connections to a public water and sewer system. An ADU must have a separate address.

(Code 2020, § 17.19.010; Ord. No. 1495, § 1, 3-16-2023)

The installation of an ADU in new and existing single-family dwellings (hereinafter "principal units") shall be allowed in the single-family R1 zone subject to specific development, design, and owner-occupancy standards. Any additional living unit not meeting the definition above or the standards and criteria below are not permitted.

The purpose of allowing ADUs is to:

1.

Provide homeowners with a means of obtaining, through tenants in either the ADU or the principal unit, rental income, companionship, security, or services.

2.

Provide homeowners with a means of providing shelter for others who may be unable to provide for their own living and care needs. An example may be an aging family member needing housing and proximity to caregivers.

3.

Add affordable housing units to the existing housing.

4.

Make housing units available to moderate-income people who might otherwise have difficulty finding homes within the city.

5.

Develop housing units in single-family neighborhoods that are appropriate for people at a variety of stages in the life cycle.

6.

Protect neighborhood stability, property values, and the single-family residential appearance of the neighborhood by ensuring that ADUs are installed under the conditions of this chapter.

(Code 2020, § 17.19.020; Ord. No. 1495, § 1, 3-16-2023)

ADUs shall meet the following standards and criteria:

1.

An ADU must have a separate entrance from the principal unit.

2.

An ADU must have a separate address from the principal unit. Internal units will be addressed with a fractional number (½) and detached or attached to a principal unit shall have a letter designation (A) added to the principal unit's address.

3.

Detached or attached additional dwelling units must include addressing signage on any sight-obscuring fence between the entry and the public sidewalk.

4.

Signage indicating dogs on premises must be posted if the entry to an ADU is within a fenced area also utilized for pets. This signage is necessary because an ADU may be located in a side or read yard where pets are commonly kept and an emergency responder should be informed of the pet's presence upon arrival to a fenced area.

5.

Certification by the city public works director or their designee that the water supply and sewage disposal facilities are adequate and separated to provide separate metering and billing for the projected number of residents.

6.

An ADU may be within, attached to, or detached from the principal unit or existing accessory structures, such as a garage.

7.

An ADU may be developed with either an existing or a new principal unit to be constructed and occupied concurrently with the ADU.

8.

Only one internal or one attached and one external ADU may be created for a maximum of two ADU units per principal unit.

9.

The existing lot must meet the minimum lot size standards in the underlying zone to be eligible for an ADU. Nonconforming undersized lots are not eligible for an ADU.

10.

To maintain the character of the neighborhood, the lot coverage for the ADU, principal unit, and accessory structures in total is limited to the lot coverage allowed in the base zone. No additional lot coverage is allowed for an ADU.

11.

An ADU total square footage is limited to 40 percent of the principal structure's area, up to a maximum of 800 square feet. An ADU must contain at least 300 square feet of living space.

12.

Height limitations for accessory structures do not apply to ADUs. The maximum allowed height for an ADU is 25 feet in height for a detached ADU and 35 feet for attached ADU addition to the principal unit. Additions within the footprint of the principal unit shall be limited by the maximum height for structures in the base zone.

13.

Walkway access to the public street is required either through dedicated access or shared access with the principal unit. Walkways must be marked with the ADU address at the right-of-way frontage. Walkway accesses must be kept clear of obstacles to allow for emergency personnel access.

14.

The required walkway to the ADU must be lit to a minimum of one-half footcandle.

15.

The design and size of the ADU shall conform to all applicable standards in the building, plumbing, electrical, mechanical, fire, health, and any other applicable codes as adopted and amended in the city. When there are practical difficulties involved in carrying out the provisions of this chapter, the city administrator or their designee may grant modifications for individual cases through a Type 1 administrative review (KMC section 16.03.100.10) using the approval criteria in chapter 16.09 conditions for granting variances.

16.

To encourage the development of housing units for people with disabilities, the city administrator or their designee may allow reasonable deviation from the stated requirements to install features that facilitate accessibility. Such facilities shall be in conformance with the standards adopted in KMC title 14.

17.

Off-street parking shall be provided per Table 17.44.020(B), in addition to that which is required for the principal unit. Required parking shall be onsite and shall not include on street parking. Parking spaces include garages, carports, or off-street areas reserved for vehicles.

18.

Setbacks for all accessory dwelling units shall be subject to the standards in the base zone.

(Code 2020, § 17.19.030; Ord. No. 1495, § 1, 3-16-2023; Ord. No. 1511, § 7, 3-21-2024)

ADUs created prior to March 16, 2023, shall be registered with the building official for inclusion into the certificate of occupancy program. Application for registration must contain the name of the owner, the address of the unit, the floor area of the two dwelling units, a plot plan of the property, evidence of the date of establishment of the unit, evidence of the use for the six-month period prior to the application for registration, and a signature of the owner.

(Code 2020, § 17.19.040; Ord. No. 1495, § 1, 3-16-2023)

System development charges for water and sewer connections shall apply to an accessory dwelling unit at one-third the residential rate rounded to the nearest dollar.

(Code 2020, § 17.19.050; Ord. No. 1495, § 1, 3-16-2023)

Application for a building permit for an ADU shall be made to the building official in accordance with the permit procedures established in KMC title 14.

(Code 2020, § 17.19.060; Ord. No. 1495, § 1, 3-16-2023)