Chapter 17.10
ACCESSORY DWELLING UNITS
Sections:
17.10.040 Development standards.
17.10.010 Established.
There is established the accessory dwelling unit (ADU) and the standards and regulations by which ADUs may be permitted therein. (Ord. 20-02 §2(part)).
17.10.020 Purpose.
An accessory dwelling unit (ADU) is a smaller, subordinate dwelling unit on a lot with, or in, an existing or new single-family residence. 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:
A. Provide for a range of choices of housing in the city;
B. Provide additional dwelling units, thereby increasing densities with minimal cost and disruption to existing neighborhoods; and
C. Enhance options for families by providing opportunities for older or younger relatives to live in proximity while maintaining a degree of privacy. (Ord. 20-02 §2(part)).
17.10.030 Applicability.
Accessory Dwelling Units on Residential Lots. A single-family residence with an accessory dwelling unit is different from a duplex because the intensity of use is less due to the limitations of size, and it has the appearance of a single-family structure. An accessory dwelling unit that meets the requirements of this section may be allowed in the R-1, R-2, and rural residential zones. (Ord. 20-02 §2(part)).
17.10.040 Development standards.
A. No more than one 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 or more single-family residences shall not be permitted to have an accessory dwelling unit.
B. Lots must have a minimum of one thousand five hundred square feet of available property to be allowed to build a detached ADU. All new detached ADUs must meet the required setbacks for their appropriate zone and requirements of subsection (D)(5) of this section.
C. The design standards shall conform to all applicable building, electrical, mechanical, fire and any other applicable codes as adopted within the Colfax Municipal Code.
D. An accessory dwelling unit may be created through:
1. Internal conversion within an existing dwelling;
2. The addition of new square footage to the existing house or to a garage and any addition thereto and is located at least twenty feet back from the front property line;
3. Conversion of an existing garage if the garage is set back at least twenty feet from the front property line;
4. Inclusion in the development plans for, or as part of, the construction of a new single-family detached dwelling unit; or
5. A separate detached dwelling unit on the same lot as the primary dwelling unit when the accessory unit is located at least ten feet behind the most distant back or side wall or other structural element of the primary dwelling unit structure and placed on a permanent foundation;
6. Mobile or movable tiny homes are not considered an accessory dwelling unit for the purposes of this section.
E. 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.
F. Building height is limited to twenty-five 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.
G. Reserved.
H. For purposes of this section, an accessory structure which contains an accessory dwelling unit may not cover more than ten percent of the total site area.
I. The total gross floor area of an accessory dwelling unit shall be a minimum of three hundred square feet but not exceed eight hundred square feet or forty percent of the primary dwelling’s living area. The primary living area must be one thousand square feet or more. The living area of the primary unit excludes uninhabitable floor area and garage or other outbuilding square footage whether attached or detached.
J. Reserved
K. Parking. One off-street parking space is required for all ADUs. A driveway permit will be required per the terms of Chapter 12.08.
L. Reserved.
M. 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, window style and placement, other architectural features and landscaping.
N. For an accessory dwelling unit created by internal conversion or by an addition to an existing primary dwelling, only one entrance may be located on the front of the house, unless the house already contains an additional front door before the conversion. Secondary entrances should be located on the side or rear of the primary residence to the extent possible.
O. An accessory dwelling unit shall not be located in a dwelling or on a lot where a home occupation is operating.
P. An accessory dwelling unit shall connect to the existing service lines prior to connecting to public sewer and water. A pre-inspection of existing water and sewer lines will be required to ensure each are of proper size and material. The property owner may be required to upgrade existing water and sewer lines to accommodate the additional usage. The owner of the property will be responsible for payment of utility services and will be charged at the multi-unit rate.
Q. Accessory dwelling units shall be subject to building fees at the same rate as those imposed for single-family dwelling units.
R. Owner Occupancy. Prior to issuance of a building permit establishing an ADU, the owner shall sign and record as a deed restriction in the county auditor’s office a certification by the owner under oath in a form prescribed by the city that one 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 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(s). Sale or ownership of such unit separate from the primary residential unit is prohibited. (Ord. 20-02 §2(part)).
17.10.045 Design standards.
A. 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.
B. Roof Slopes. For buildings over fifteen 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.
C. 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:
1. Exterior materials should be of the same type, size and placement as those of the primary dwelling structure.
2. 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.
3. 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).
4. Pediments and Dormers. Each accessory dwelling unit over twenty feet in height should have either a roof pediment or dormer if one or the other of these architectural features are present on the primary dwelling. (Ord. 20-02 §2(part)).