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40.260.020 Accessory Dwelling Units
A. Purpose.
An accessory dwelling unit (ADU) is an additional smaller, subordinate dwelling unit on a lot with, or in, an existing or new house. These units are intended to provide for a greater range of choices of housing types in single-family and multifamily residential districts. Accessory dwelling units are intended to:
1. Provide for a range of choices of housing in the county;
2. Provide additional dwelling units, thereby increasing densities with minimal cost and disruption to existing neighborhoods;
3. Allow individuals and smaller households to retain large houses as residences; and
4. Enhance options for families by providing opportunities for older or younger relatives to live in proximity while maintaining a degree of privacy.
B. Applicability.
Accessory dwelling units on residential lots. A house with an accessory dwelling unit is different from a duplex because the intensity of use is less due to the limitations of size and number of bedrooms, and it has the appearance of a single-family structure. An accessory dwelling unit that meets the requirements of this subsection may be allowed in the R1-20, R1-10, R1-7.5, R1-6, R1-5 zones or on any multifamily-zoned (Residential (R) or Office Residential (OR)) lot developed with an existing single-family dwelling, except as noted herein.
C. Development Standards.
1. No more than one (1) accessory dwelling unit per legal lot is permitted and it must be accessory to a single-family residence. A lot of record lawfully occupied by two (2) or more single-family residences per Section 40.200.050 shall not be permitted to have an accessory dwelling unit, unless the lot is short platted under Chapter 40.540 of this code. If a short plat is approved, an accessory
dwelling unit for each dwelling unit is permitted only if all dimensional standards of the underlying zone and all other provisions of this section are met.
2. No accessory dwelling unit shall be permitted on a lot of less than five thousand (5,000) square feet.
3. The applicant must apply for a building permit for an accessory dwelling unit. An accessory dwelling unit shall comply with applicable building, fire, and health and safety codes. An accessory dwelling unit cannot be occupied until a certificate of occupancy is issued by the building department.
4. An accessory dwelling unit may be created through:
a. Internal conversion within an existing dwelling;
b. The addition of new square footage to the existing house or to a garage and any addition thereto is located at least forty (40) feet back from the front property line;
c. Conversion of an existing garage if the garage is set back at least forty (40) feet from the front property line;
d. Inclusion in the development plans for, or as part of, the construction of a new single-family detached dwelling unit; or
e. A separate detached dwelling unit on the same lot as the primary dwelling unit when the accessory unit is located at least ten (10) feet behind the most distant back or side wall or other structural element of the primary dwelling unit structure.
f. Mobile homes are not considered an accessory dwelling unit for the purposes of this subsection.
5. An accessory dwelling unit shall conform to existing zoning requirements for the primary residence, including, but not limited to lot coverage, front, side and rear setbacks.
6. Building height is limited to twenty-five (25) feet for a detached accessory dwelling unit. Building height requirements of the underlying zone do apply to the accessory dwelling unit for internal conversion or structural addition to the existing primary dwelling.
7. The addition of an accessory dwelling unit shall not make any lot, structure or use nonconforming within the development site. All setbacks for the zone shall be met except as allowed in Section 40.200.070 or Section 40.550.020.
8. For purposes of this section, an accessory structure (such as a garage or other outbuilding, but not a detached accessory dwelling unit) which contains an accessory dwelling unit may not cover more than ten percent (10%) of the total site area.
9. The total gross floor area of an accessory dwelling unit shall not exceed forty percent (40%) of the area of the primary dwelling’s living area. The living area of the primary unit excludes unhabitable floor area and garage or other outbuilding square footage whether attached or detached.
10. An accessory dwelling unit shall not contain more than one (1) bedroom.
11. Parking. No minimum on-site parking spaces are required for an accessory dwelling unit in areas with on-street parking available. On-street parking is defined as parking spaces legally available for parking of vehicles. Posted time- or day-restricted parking spaces are not considered as available for purposes of this section.
12. One (1) parking space for the accessory dwelling unit is the minimum required if on-street parking is not available. If no parking space is available on-site, or on-street, a joint agreement for off-site parking may be presented in accordance with Section 40.340.010(A)(5).
13. The exterior appearance of an addition or detached accessory dwelling unit shall be architecturally compatible with the primary residence. Compatibility includes coordination of architectural style, exterior building materials and colors, roof form and pitch, window style and placement, other architectural features and landscaping. See Section 40.260.020(D).
14. For an accessory dwelling unit created by internal conversion or by an addition to an existing primary dwelling, only one (1) entrance may be located on the front of the house, unless the house contained additional front doors before the conversion. Secondary entrances should be located on the side or rear of the primary residence to the extent possible.
15. An accessory dwelling unit shall not be located in a dwelling or on a lot where a Type II home business is operating.
16. An accessory dwelling unit shall connect to public sewer and water.
17. A home or lot which has an accessory dwelling unit which was established prior to adoption of this ordinance may be approved for a building permit subject to the provisions of Chapter 40.530.
18. Accessory dwelling units shall be subject to impact fees at the same rate as those imposed for multifamily dwelling units.
19. Owner Occupancy. Prior to issuance of a building permit establishing an ADU, the applicant shall record as a deed restriction in the County Auditor’s office a certification by the owner under oath in a form prescribed by the responsible official that one (1) of the dwelling units is and will continue to be occupied by the owner of the property as the owner’s principal and permanent residence for as long as the other unit is being rented or otherwise occupied. The owner shall maintain residency for at least six (6) months out of the year, and at no time receive rent for, or otherwise allow to be occupied, the owner-occupied unit if absent for the remainder of the year. Falsely certifying owner occupancy shall be considered a violation of the zoning ordinance and is subject to the enforcement actions described in Title 32.
(Amended: Ord. 2005-04-12)
D. Design Standards.
1. Exterior Finish Materials. Plain concrete, concrete block, corrugated metal or plywood are prohibited if they are not the predominant exterior finish material on the primary dwelling, unless these materials duplicate or reflect the predominant finish.
2. Roof Slopes. For buildings over fifteen (15) feet in height, the slope of the accessory dwelling unit roof must be the same as that of the predominant slope of the primary dwelling structure.
3. Historic Structures. If an accessory dwelling unit is on the same lot as or within a historic structure which has been designated on the national, state or local historic register, the following design guidelines are applicable:
a. Exterior materials should be of the same type, size and placement as those of the primary dwelling structure.
b. Trim on edges of elements of accessory structures and additions should be the same as those of the primary structure in type, size and placement.
c. Windows in any elevation which faces a street should match those in the primary structure in proportion, i.e., same height, width and orientation (horizontal or vertical).
d. Pediments and Dormers. Each accessory dwelling unit over twenty (20) feet in height should have either a roof pediment or dormer if one (1) or the other of these architectural features are present on the primary dwelling.