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 while protecting the character of the residential neighborhood.

B.    Applicability.

1.    Accessory dwelling units 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, subject to the requirements of this section.

2.    A lot of record lawfully occupied by two (2) or more single-family residences per Section 40.200.050 does not qualify for an ADU, unless the lot is short platted under Chapter 40.540. If a short plat is approved, an ADU for each dwelling unit is permitted only if all dimensional standards of the underlying zone and all other provisions of this section are met.

3.    An ADU shall not be located in a dwelling or on a lot where a Type II home business is operating.

C.    Development Standards.

1.    No more than one (1) ADU per legal lot is permitted and it must be accessory to a single-family residence.

2.    No accessory dwelling unit shall be permitted on a lot of less than five thousand (5,000) square feet. An ADU shall not contain more than one (1) bedroom.

3.    ADUs require building permits to ensure compliance with applicable fire, health, and safety codes.

4.    An ADU 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;

c.    Conversion of an existing garage;

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 ADU for the purposes of this subsection.

5.    An ADU shall conform to the standards of the zone, including, but not limited to lot coverage and setbacks.

6.    Building height is limited to twenty-five (25) feet for a detached ADU. Additions to existing dwellings shall meet the height requirements of the zone.

7.    Allowable Size.

    The total gross floor area of an ADU shall not exceed eight hundred (800) square feet or forty percent (40%) of the area of the primary dwelling’s living area, whichever is less, with the following exceptions for large lots with large primary dwellings:

a.    On lots zoned R1-10 that are at least ten thousand (10,000) square feet, the maximum square footage of an ADU is one thousand (1,000) square feet, or forty percent (40%) of the area of the primary dwelling’s living area, whichever is less; and

b.    On lots zoned R1-20 that are at least twenty thousand (20,000) square feet, the maximum square footage of an ADU is fifteen hundred (1,500) square feet, or forty percent (40%) of the area of the primary dwelling’s living area, whichever is less.

    The living area of the primary unit excludes unhabitable floor area and garage or other outbuilding square footage whether attached or detached. If the primary dwelling is less than seven hundred and fifty (750) square feet, the ADU may be up to three hundred (300) square feet even though this exceeds forty percent (40%) of the primary dwelling unit’s living area. The absolute minimum area of an ADU is determined by the building code.

8.    Parking.

    One parking space shall be provided for the ADU. Parking may be provided by the following methods:

a.    On site;

b.    On-street parking; provided, that the parking space is legally available and along the ADU lot’s street frontage. Posted-time or day-restricted parking spaces do not qualify as legally available for the purposes of this section; or

c.    If no parking space is available on-site or on-street, a joint agreement for off-site parking may be used subject to Section 40.340.010(A)(5).

9.    An ADU shall connect to public sewer and water unless a sewer waiver is obtained under Section 40.370.010.

10.    ADUs shall be subject to impact fees at the same rate as those imposed for multifamily dwelling units.

11.    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.    The exterior appearance of an addition or detached ADU 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. The responsible official may approve variations as necessary to accommodate proposed energy efficient building features into the ADU.

2.    New entrances for an ADU created by internal conversion or by an addition to an existing primary dwelling shall be located on the side or rear of the primary residence unless it can be demonstrated that no feasible alternative exists.

3.    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.

4.    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.

5.    Historic Structures. If an ADU 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.

6.    Accessibility. To encourage the development of ADA-accessible housing units, the responsible official may allow reasonable deviation from the requirements of this section for features that facilitate accessibility.

E.    Process.

    Accessory dwelling units require Type I site plan review under Section 40.510.010. Building permits may be submitted at the same time as the site plan review.

(Amended: Ord. 2010-08-06)