A. Applicability. This section applies to any secondary attached or detached dwelling and details the standards required to ensure these dwelling types remain incidental and subordinate to the principal permitted dwelling.
B. General Standards.
1. Principal Dwelling: A principal permitted dwelling with a valid zoning certificate and certificate of occupancy, or a principal permitted dwelling under construction with a valid building permit, must be present on the subject property.
2. Number Allowed: No more than one permanent additional dwelling including, but not limited to, an additional farm dwelling, caretaker dwelling, or a secondary dwelling shall be permitted on a property. Conversion of an existing attached garage or basement of the principal permitted dwelling counts as the allowed one permanent additional dwelling.
3. Occupancy: Either the principal dwelling or the secondary dwelling must be continuously occupied by at least one (1) person having ownership interest in the subject property.
4. Property Size: The subject property shall have a minimum property size of at least six thousand (6,000) square feet.
5. Dimensional Standards. All secondary dwellings shall meet the dimensional standards for the applicable zoning district.
C. Design Standards.
1. Size. A secondary dwelling may be between three hundred fifty (350) square feet up to a maximum of one thousand two hundred (1,200) square feet or sixty percent (60%) of the square footage of above-ground living space of the principal dwelling, whichever is less. Garage and/or shop space included in an accessory structure containing a secondary dwelling shall not count against the allowed square footage of the secondary dwelling.
a. Sixty percent (60%) Calculation: The square footage of covered outdoor space, basements or attached/detached garages associated with the principal dwelling must be excluded from the sixty percent (60%) calculation.
2. Bedrooms: Secondary dwellings are limited to a maximum of three (3) bedrooms. A bedroom includes enclosed conditioned spaces over seventy (70) square feet with a privacy door and separate means of egress.
3. Parking. Off street parking shall be provided as per section 8-4G-6 of this title in addition to the required off street parking for the principal dwelling.
4. Appearance. The secondary dwelling should be complementary with the principal permitted dwelling in that it:
a. Has a similar roof pitch; and
b. Has a compatible color scheme.
5. Facilities. The secondary dwelling shall have separate kitchen and bathroom facilities from the principal permitted dwelling.
6. Utilities: The secondary dwelling shall be provided with utilities which may be metered separately - including gas, electric, communications, water and sewer all subject to the approval of applicable utility companies and public agencies.
7. Entry: Secondary dwellings shall be provided with a primary point of ingress and egress separate from the principal dwelling.
8. Emergency Access: Secondary dwellings shall be provided with a separate address, a unique identifier, or other means to enable emergency service providers to identify and distinguish the dwelling unit from the principal dwelling. Adequate physical access for emergency services to both the principal and secondary dwellings shall be provided.
9. Foundation: Secondary dwellings shall be placed on a foundation.
D. Additional Standards for Detached Secondary Dwelling Units.
1. Location: A secondary dwelling shall not be located in the front yard unless the principal dwelling, and its address indicator can remain unobscured, and one or more of the following can be demonstrated:
a. The depth of the lot or parcel is two hundred fifty feet (250') or less; or
b. The configuration of the property and location of the principal dwelling would preclude the location of the secondary dwelling to meet the required back yard and/or side yard setbacks.
2. Outdoor Space. A minimum of 50 square feet of outdoor space like a porch, patio, or balcony shall be provided for the exclusive use of the residents of the dwelling. This square footage shall not count against the allowed square footage of the secondary dwelling.
E. Conversion of an existing structure.
1. An existing garage, basement or a detached accessory structure may be converted into a secondary dwelling, provided that the conversion or structure meets the standards of this section, except for the requirements of section 8-5-3-40.C.4.
2. If such conversion requires exterior work and/or an addition to the existing garage, basement, or detached accessory structure such exterior work and/or addition should be complementary to the existing building construction.
3. Such conversion shall comply with all applicable requirements of the Ada County building code, as set forth in title 7, chapter 2 of this code, any applicable plumbing or electrical code requirements, and any applicable off-street parking requirements for both the principal and secondary dwellings.
F. Deed Restriction. A recorded deed restriction is required ensuring compliance with the following requirements and shall be submitted prior to issuance of a certificate of occupancy or final building permit inspection.
1. Document Requirements: The deed restriction or covenant shall address the following topics:
a. The secondary dwelling shall not be sold or owned separately from the principal dwelling.
b. The secondary dwelling may be utilized as habitable space, only so long as either the principal dwelling or the secondary dwelling is occupied by at least one individual with ownership interest in the property.
c. In the event that a minimum of one (1) person having ownership interest in the property ceases to occupy a dwelling on the property, the secondary dwelling shall automatically become non-habitable space, shall not be used as a dwelling and shall not be rented or leased for any purpose.
d. The above restrictions shall be binding upon any successor in ownership of the property as long as the secondary dwelling exists on the property. (Ord. 389, 6-14-2000; amd. Ord. 715, 12-3-2008; amd. Ord. 902, 10-2-2019; Ord. 970, 3-13-2024)