14.23.071 Design Criteria For Accessory Dwelling Units (ADU)

14.23.071 Design Criteria For Accessory Dwelling Units (ADU).

A. Intent and Specific Design Criteria. Accessory dwelling units are a necessary and desirable use for all residential neighborhoods. Because of the increased density they represent and providing of an additional dwelling unit in a non-conventional way, it is important to have the units blend in with and complement the primary use on lots. It is also important to ensure that both residents of the accessory dwelling unit and main unit have adequate privacy. To do this, special design features are required. Additionally, it is important to promote compatibility and complementary design of accessory structures with primary structures in an area to protect the character of the neighborhood.

B. Design Requirements. In order to assure that the development of all accessory dwelling units and those accessory structures to which this section is applicable is consistent with policies of the Comprehensive Land Use Plan, the following special design features and provisions shall apply to all accessory dwelling units:

1. Size. An accessory dwelling unit shall be limited in size to fifty percent of the size of the main unit and not to exceed eight hundred fifty square feet in floor area, except as provided in subsection C of this section.

2. Density Calculations. For the purposes of calculating residential density, accessory dwelling units shall not count as a dwelling unit.

3. Only One ADU per Lot Permitted. There shall not be more than one accessory dwelling located on a lot in addition to the single-family dwelling.

4. Subordinate to Main Use. The accessory dwelling unit shall be clearly subordinate to the primary use as demonstrated in the building design and location. Design for this purpose shall include the following considerations:

a. Integration with Main Unit and Appearance. If the unit is integrated into the main unit, design shall present the overall appearance of the structure as an individual single-family residence. Designs which give the impression of a “duplex” shall not be permitted. A separate entrance to the accessory dwelling may be in view from public right-of-way, but should blend in to the primary unit in a way that does not indicate its function as an entrance to a separate unit.

b. Detached from Main Unit and Appearance. If the accessory dwelling is detached from the main unit, it shall be located in a position on the lot that presents a less dominant focus than the primary use. Design shall present the general impression that it is clearly an accessory building to the primary use.

c. Above the Garage and Appearance. If the unit is located on top of a detached garage, design shall complement the architectural style of the main residence while maintaining the primary unit as the main emphasis and focus for the lot.

5. Privacy for Residents Is a Main Focus. Maintain privacy of adjacent residences by using a combination of native and drought-tolerant landscaping, vegetated LID facilities, screening, fencing, and window and door placement to reduce the opportunity of accessory dwelling units having direct visibility into windows, porches and decks. Care shall be given to location of windows so that they do not intrude onto the private space of adjacent neighbors. If the garage and ADU are rear loaded, for enhanced security, windows are encouraged to provide eyes on the alley.

6. Driveway Consolidated. The driveway to a separate, detached accessory unit shall be consolidated with the existing driveway area.

7. Distance from Other Structures. For those accessory units that are detached, distance separation between the primary residence shall meet building code requirements.

8. Livability of Neighborhood. In order to ensure that an accessory dwelling unit fits into and contributes to the livability of the neighborhood, design and construction shall:

a. Roof Design. Ensure that roof breaks and pitch closely relate to the primary residence. Window proportions shall complement the accessory unit;

b. Materials. Use similar exterior materials (roof, siding and trim) and a color that complements the primary residence;

c. Height of Roof Ridge. In general, the roof ridge of the primary residence should be higher than the accessory dwelling unit. An exception is when the accessory dwelling unit is built onto the second story of an existing unit.

9. Parking. At least one parking space should be provided for the accessory dwelling unit. This parking may be provided in a garage, a parking space adjacent to the alley, or, if available, by on-street parking.

10. Pedestrian Access. A pedestrian walkway from the street or alley to the primary entrance of an accessory dwelling unit shall be provided. Such walkway may be shared with a driveway.

11. Accessory Structures. To promote compatibility and consistency of design and neighborhood aesthetics, all accessory structures requiring a building permit shall be required to have design review. Review shall ensure accessory structures are constructed of similar material and in a complementary design to primary structures on site and on immediately adjacent lots. Provided, a different design or material may be approved if it is demonstrated that the design and material will enhance the general character and appearance of the neighborhood and promote policies of the Comprehensive Land Use Plan. All applications for construction of such accessory structures shall demonstrate that the proposed structure will be in compliance with any protective covenants or other restrictions applicable to the property.

1. Intent. The intensity of use and impacts from an accessory dwelling unit is expected to be less than that of the primary dwelling, because it is intended to be accessory to the main unit and designed to be limited in scope. It is not designed to expect a double loading of full size residential units on lots intended for single-family development. This expectation is important in the overall planning of infrastructure and services to a subdivision. This design limitation protects the overall quality and character of the subdivision and the planned capacity of subdivision infrastructure, while still allowing for the extraordinary benefits and advantages the ADU is intended to provide. The accessory dwelling unit must necessarily be subordinate to the primary use.

To this purpose, limitations have been established for the size of the accessory dwelling units. However, there may be circumstances, applicable to the subject property and existing buildings, that require a smaller size than permitted to limit identified impacts. Alternately, the city realizes there may also be circumstances, applicable to existing structures and the subject property, that would make a larger size more practical or functional without compromising the intent or the subordinate nature of the proposed ADU.

2. Guidelines. To accommodate special circumstances the following guidelines have been developed to allow reasonable variation from the size standards of subsection (B)(1) of this section. When reviewing an accessory dwelling unit for size requirements the following guidelines and criteria shall be applied:

(1) Basis for Consideration. When a request is for an ADU of a size larger than the established maximum, the following situations may be valid reasons for the administrator to allow an increased size. Generally, this will involve the following situations where the proposed size of the ADU is logical given circumstances and if permitted would have no discernable impact on the appearance of the main unit or in meeting the intent of design requirements of this chapter:

(a) The ADU is located within the existing main unit, such as a basement unit, and the logical use of the floor area exceeds the square foot limitation;

(b) The ADU is located within the existing main unit and use of the area, rooms and configuration of existing space proposed for the ADU is more logical and functional than options of trying to reduce its size simply to fit the size standard;

(c) Special circumstances considering the configuration of the property and/or existing buildings make the increased size logical from a building or design standpoint and more functional.

(2) Mandatory Criteria for Increase in Size. Any request to increase the size must meet all of the following criteria:

(a) The proposed ADU can meet all other design expectations of this chapter and is subordinate to the main unit both functionally and in appearance.

(b) The proposed ADU will not have a discernable impact in the context of the neighborhood in which it is located, considering infrastructure, support services and neighborhood character.

(c) The increased size is logical from a design standpoint, given configuration of existing structures or organization of space, and is the least amount of size necessary to accommodate the circumstances.

(1) Compromise Design Expectations. Given the unique nature of the site and/or structures, the full size permitted for the ADU will compromise other design expectations needed to make the ADU subordinate to the main structure or meet the intents of this chapter;

(2) Impacts to Neighborhood Character, Infrastructure or Services. The proposed ADU while meeting the allowed size limit will have a discernable adverse impact in the context of the neighborhood in which it is located considering infrastructure, support services or neighborhood character;

(3) Not Logical Given Site Considerations. The proposed ADU, while meeting the allowed size limit, is not logical from a design standpoint given either configuration of existing structures, the organization of space, size of lot, or space available and the full size is not necessary to accommodate the intended use and function of an ADU. (Ord. 1539 §11, 2019; Ord. 1496 §7, 2016; Ord. 1367 §3, 2011).