17.08.060 Accessory dwelling units (ADU).
A. Purpose. The purpose of this section is to regulate the establishment of ADUs in order to:
1. Make it possible for adult children to provide care and support to a parent or other relatives in need of assistance; and/or
2. Provide increased security and companionship for homeowners; and/or
3. Provide the opportunity for homeowners to gain the extra income necessary to help meet the rising costs of home ownership; and/or
4. Provide for the care of disabled persons within their own homes; and/or
5. Provide for a more diverse and affordable housing stock.
B. Development Standards. All ADUs within the town must comply with the following requirements:
1. An ADU may be attached to, included within, or detached from, the principal unit in any zone which allows a single-family housing unit, duplex, triplex, townhome, or other housing unit.
2. An ADU may be located within any zone when utilized as a caretaker’s quarters for public utility facilities.
3. Two accessory dwelling units are allowed on lots that are located in zoning districts which allow for single-family homes in the following configurations:
a. One attached ADU and one detached ADU;
b. Two attached ADUs; or
c. Two detached ADUs, which may be comprised of either one or two detached structures.
4. ADUs may be developed on any lot that meets the minimum lot size required for the principal unit.
5. ADUs must meet all development standards applicable to the principal unit, including maximum site coverage, minimum yard requirements, and height limitations, with the following exceptions:
a. Detached ADUs may be sited at a lot line if the lot line abuts a public alley, unless the town routinely plows snow on the public alley.
b. ADUs converted from existing structures, including but not limited to detached garages, will be allowed, even if they violate current code requirements for setbacks or lot coverage.
6. Public street improvements shall not be required as a condition of permitting accessory dwelling units.
7. Required off-street parking spaces including garages, carports, or off-street areas reserved for vehicles which may be in tandem, shall be calculated as follows:
a. Only one off-street parking space per unit is required on lots smaller than 6,000 square feet before any zero lot line subdivisions or lot splits;
b. Two off-street parking spaces per unit are required on lots greater than 6,000 square feet before any zero lot line subdivisions or lot splits.
c. Exceptions. ADUs within one-half mile walking distance of a major transit stop shall not be required to meet off-street parking space requirements.
8. In order to encourage the development of housing units for people with disabilities, the town planner in consultation with the building official may allow reasonable deviation from the stated requirements to install features that facilitate accessibility.
C. ADUs shall not be allowed on lots designated with critical areas or their buffers as designated in RCW 36.70A.060, or to a watershed serving a reservoir for potable water if that watershed is or was listed, as of the effective date of the ordinance codified in this section, as impaired or threatened under Section 303(d) of the federal Clean Water Act, unless deemed a compatible use as determined by the town planner in consultation with the building official.
D. Compliance With Applicable Codes and Permits. ADU construction shall conform to all codes which are required for any new residential construction. An approved building permit is needed prior to construction and a certificate of occupancy will be required prior to occupancy of the ADU.
1. Exception. Applicable impact fees for an ADU are limited to 50 percent of the impact fees that would be imposed on the principal unit.
E. Sewer and Water Connections. The ADU shall be served by the existing primary residence’s sewer and water connections and meters, unless a septic system is approved for wastewater disposal.
F. Subdivision/Sale. The ADU, or the land on which the ADU is located, shall not be subdivided, sold, or otherwise segregated in ownership from the primary residence or the land on which the primary residence is located without completion of a subdivision or short subdivision process, as approved by the town of South Prairie, or an approved condominium process.
G. ADUs shall not be utilized for short-term rentals. [Ord. 631 § 1 (Att. A), 2023.]