18A.37.120 Accessory Dwelling Unit (ADU).
A. The establishment of an ADU shall be subject to the following general requirements:
1. One ADU shall be allowed per lot of record as an accessory use in conjunction with any detached single-family structure in all zones. ADUs shall not be included in density calculations.
2. An ADU shall be converted to another permitted use or shall be removed if one of the two dwelling units is not owner occupied.
3. An ADU shall be permitted as a second dwelling unit attached to, or detached from, the principal dwelling.
4. A detached ADU may be any dwelling permitted in the applicable land use classification.
5. New construction of a detached ADU or conversion of an existing detached structure to an ADU shall not be permitted within the required front, side, or rear yard setback. An exception to the required rear yard setback may be allowed if the rear yard abuts an alley.
6. If an ADU is created by constructing a new detached structure, the building height of the ADU shall not be greater than the principal dwelling's building height, unless the ADU is above a detached garage.
B. Size. An ADU shall be no greater than 1,000 square feet when located in an Urban Growth Area. When located outside an Urban Growth Area, the size may increase to 1,250 square feet.
1. The following areas shall be counted when calculating the size of an ADU: any area with a ceiling height of 7 feet or more; all bathroom and basement areas with a ceiling height of 6 feet, 8 inches or more; and any areas with sloped ceilings where 50 percent of said area has a ceiling height of 5 feet or more.
2. When calculating the square footage of an attached ADU, all measurements shall be taken from the interior walls.
3. When calculating the square footage of a detached ADU, all measurements shall be taken from the exterior walls and shall include each level of the structure, excluding only the garage, covered porches, and any levels not accessed by a permanent stairway structure.
C. Design. The following standards shall apply when the separation between the principal dwelling and proposed accessory dwelling is less than 100 linear feet:
1. The entrance to an attached ADU shall not be directed toward any front yard unless utilizing an existing doorway.
2. Detached ADUs shall be no closer to the front lot line than the front edge of the principal dwelling. This provision shall not apply to waterfront lots regulated pursuant to Title 18S PCC, Development Policies and Regulations – Shorelines.
3. Parking. One off-street parking space shall be required for the ADU in addition to off-street parking required for the principal dwelling pursuant to PCC 18A.35.040, Off-Street Parking.
D. Application. Any owner occupant seeking to establish an ADU shall apply for approval in accordance with established procedures. These procedures shall include:
1. The owner occupant shall apply for a Building Permit for an ADU. A complete application form must demonstrate that all size thresholds and design standards are met.
2. An affidavit affirming that the owner will occupy the principal dwelling or the ADU and agreeing to all the general requirements as provided in this Section is required.
3. Prior to occupancy of the ADU, the owner occupant shall record a notice on the property title acknowledging the existence of the ADU with the Pierce County Auditor. Such notice shall be in a form as specified by the Department and shall include as a minimum:
a. The legal description of the property which has been approved for an ADU;
b. The applicability of the restrictions and limitations contained in this Section;
c. A copy of the County-approved floor plan and site plan; and
d. The property owner's signature on the notice, which shall be notarized prior to recording the notice.