Chapter 17.102
ACCESSORY DWELLING UNITS*
Sections:
17.102.020 Locations permitted.
17.102.040 Criteria for approval for conditionally permitted accessory dwelling units.
17.102.050 Design and development standards.
* Prior legislation: Ordinances 2554, 2673 and 2728.
17.102.010 Purpose.
This chapter provides for accessory dwelling units in certain districts and on lots developed or proposed to be developed with single-family dwellings. Such accessory dwellings contribute to a diversified housing stock and increase affordability of housing while preserving neighborhood stability and property values. (Ord. 2784 § 2 (Att. A), 2011)
17.102.020 Locations permitted.
One accessory dwelling unit per single-family detached dwelling unit is permitted or conditionally permitted in residential zoning districts as determined by the district regulations. (Ord. 2784 § 2 (Att. A), 2011)
17.102.030 Permit procedures.
A. The following accessory dwelling units shall be permitted accessory uses within the applicable zoning districts subject to administrative approval of a building permit:
1. Any detached accessory dwelling unit substantially compliant with ADU Templates 1 through 4 as included in “Accessory Dwelling Units, A Guide for Property Owners for ADU Development” as determined by the director.
2. Any detached accessory dwelling unit meeting the residential design standards as permitted for the main residence in the zoning district and compliant with the size standards contained in Table 17.102.A.
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If the area of the lot is: |
Net floor area of accessory unit shall not exceed: |
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6,000 – 8,000 sq. ft.: |
The lesser of 50% of the primary residence or 600 sq. ft. |
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8,001 – 11,000 sq. ft.: |
The lesser of 50% of the primary residence or 800 sq.ft. |
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Greater than 11,000 sq. ft.: |
The lesser of 50% of the primary residence or 1,000 sq. ft. |
3. Any attached accessory dwelling unit located within the same structure as the primary residence provided it meets the size standards contained in Table 17.102.B. Such structure shall have only one front door so as to maintain the appearance of a single-family residence.
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If the area of the house is: |
Net floor area of accessory unit shall not exceed: |
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Under 2,000 sq. ft.: |
50% of the primary residence |
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2,000 – 2,999 sq. ft.: |
The lesser of 40% of the primary residence or 1,000 sq. ft. |
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3,000 – 4,999 sq. ft.: |
The lesser of 30% of the primary residence or 1,200 sq.ft. |
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5,000 sq. ft. or more: |
The lesser of 20% of the primary residence or 1,500 sq. ft. |
B. The following accessory dwelling units shall be conditionally permitted accessory uses within the applicable zoning districts subject to a conditional use permit granted by the hearing examiner.
1. Conversion of an existing accessory structure, noncompliant with the accessory structure setbacks, on an otherwise compliant lot may be conditionally permitted without a variance. Under no circumstance may the accessory structure encroach onto adjacent private or public property or exceed 1,000 square feet of living area.
2. A detached accessory dwelling unit not meeting the requirements in subsection (A) of this section shall be conditionally permitted within the zoning districts specified in BMC 17.102.020 provided the size does not exceed 1,000 square feet. (Ord. 2970 § 1 (Exh. A), 2021; Ord. 2784 § 2 (Att. A), 2011)
17.102.040 Criteria for approval for conditionally permitted accessory dwelling units.
Before approval of a conditional use permit for a detached accessory dwelling unit, the hearing examiner shall find that:
A. Exterior design of the accessory unit is compatible with the existing residence on the lot through architectural use of building style, height, construction materials, colors, landscaping, and other methods that conform to acceptable construction practices.
B. The location and design of the accessory unit maintains a compatible relationship to adjacent properties and does not significantly impact the privacy, light, air, solar access or parking of adjacent properties.
C. The structure generally limits the stairs, decks, entry doors, and major windows to the walls facing the primary residence, or to the alley or street and away from adjacent properties where applicable.
D. Conversion of an existing accessory structure into a dwelling unit does not result in encroachment into the setback where none existed before conversion, and does not increase any existing encroachment into the setback. (Ord. 2970 § 1 (Exh. A), 2021; Ord. 2784 § 2 (Att. A), 2011)
17.102.050 Design and development standards.
All accessory dwelling units must conform to the following standards:
A. The side yard and rear yard setbacks for detached accessory dwelling units shall not be less than as determined by BMC 17.104.010. Detached accessory dwelling units shall not be forward of the primary unit in relation to any public street. Detached accessory dwelling units are not eligible for variances to setbacks.
B. Attached accessory dwelling units shall meet the same setbacks as a main building in the zoning district. Attached accessory dwelling units are not eligible for variances to setbacks.
C. The majority property owner must occupy either the primary or accessory dwelling as his or her principal place of residence.
D. When an accessory dwelling unit is adjacent to a side street or alley, every effort shall be made to orient the accessory dwelling unit toward the side street or alley with the front access door and windows facing the side street or alley. No preference is given to either the side street or alley in regard to building orientation.
E. Parking shall be located off of an alley wherever feasible. Parking shall be provided for the ADU as required by this code. Parking does not need to be in an enclosed building.
F. The design of the accessory unit shall relate to the design templates, or the applicable residential design standards, or the design of the primary residence by use of compatible exterior wall materials, window types, door and window trims, roofing materials and roof pitch.
G. The site plan shall provide open space and landscaping that are useful for both the accessory dwelling unit and the primary residence. Landscaping shall provide for the privacy and screening of adjacent properties.
H. For new construction, exterior walls facing a street or alley that are over 24 feet in length shall be articulated by at least two feet.
I. Detached accessory dwelling units are limited to 28 feet in height. (Ord. 2784 § 2 (Att. A), 2011)
17.102.060 Design bonus.
A lot coverage bonus shall be provided for use of superior design. A five percent increase above the base impervious surface lot coverage allowance for the zoning district shall be available. A bonus shall be awarded by the director for a detached ADU that includes five of the following design elements:
A. A covered front porch or entry;
B. Gable-ended or shed-style dormers;
C. A stepped or articulated roof ridge line, not achieved with dormers;
D. Architectural projections on wall planes such as a bay window or pop-out;
E. Window mullions in a traditional pattern;
F. Prominent window and door trim that exceeds the standards in Chapter 17.121 BMC;
G. Use of brick, stone or cultured stone as a design accent;
H. Knee braces on gable ends;
I. Decorative detail element not included above as approved by the director. (Ord. 2784 § 2 (Att. A), 2011)
17.102.070 Deed restrictions.
Before obtaining a certificate of occupancy for an accessory dwelling unit, the property owner shall file with the county recorder a declaration of restrictions containing a reference to the deed under which the property was acquired by the present owner and stating that:
A. The accessory unit shall not be converted to a condominium or sold separately.
B. The unit is restricted to the approved size.
C. The occupancy or use permit for the accessory unit shall be in effect only so long as either the main residence, or the accessory unit, is occupied by the majority owner of record as the owner’s principal place of residence.
D. The above declarations are binding upon any successor in ownership of the property; lack of compliance shall be cause for code enforcement and/or revoking the occupancy or use permit.
E. The deed restrictions shall lapse upon removal of the accessory unit. (Ord. 2784 § 2 (Att. A), 2011)