Williams-Ballin Revocable Trust et al Design Review (P6070)

The applicant requests Design Review approval to authorize the construction of additions to an existing primary residential structure (single-family residence) and the installation of certain detached residential accessory structures (barbeque, pool equipment area, bike shed, retaining wall, and sports court), all located on a developed lot in the unincorporated community of Kentfield.

The proposed additions to the existing single-family residence would total approximately 668 square feet and would be constructed across three levels on the southern front façade of the building. The approximately 668 square feet of proposed development would appear to result in a total building area of 3,721 square feet, a total floor area of 3,569 square feet, and a total floor area ratio of 30 percent on the 11,900-square-foot (0.27-acre) lot, as calculated pursuant to the applicable definitions set forth in Marin County Code Section 22.130.030 (Definitions of Specialized Terms and Phrases). The total floor area, maximum height, and minimum setbacks for each proposed addition are provided below and enumerated as items a through c.

1. The first addition would be located on the first and lowest level of the residence and would consist of 451 square feet of floor area. It would reach a maximum height of 11 feet, 3 inches above grade, and would maintain the following minimum setbacks: 67 feet, 4 inches from the southern front property line; 10 feet from the eastern side property line; 49 feet, 10 inches from the western side property line; and 89 feet, 4 inches from the northern rear property line.
2. The second addition would be located on the second level of the residence and would consist of 284 square feet of floor area. It would reach a maximum height of 18 feet, 9 inches above grade, and maintains the following minimum setbacks: 73 feet from the southern front property line; 10 feet from the eastern side property line; 50 feet, 9 inches from the western side property line; and 85 feet, 2 inches from the northern rear property line.
3. The third addition would be located on the third and highest level of the residence and would consist of 62 square feet of floor area. It would reach a maximum height of 22 feet, 5 inches above grade, and maintains the following minimum setbacks: 83 feet from the southern front property line; 10 feet from the eastern side property line; 39 feet, 9 inches from the western side property line; and 84 feet, 7 inches from the southern rear property line.

The proposed detached residential accessory structures consist of affixed improvements, including a barbeque, pool equipment area, retaining wall, bike shed, and sports court. The majority of these accessory structures would exceed a development standard established either by the governing Minimum Lot Size “-B2” Zoning District pursuant to Marin County Code Section 22.14.050, Table 2-11 (Minimum Lot Size “-B” Combining District Standards), or by the general development standards set forth in Marin County Code Chapter 22.20 (General Property Development and Use Standards). The sports court, however, requires Design Review irrespective of its conformance with development standards. The maximum height and/or minimum setbacks for each proposed site improvement are provided below and enumerated as items a through e.

1. The barbeque would be located within the minimum required 10-foot side yard setback for the Minimum Lot Size “-B2” Zoning District, maintaining a minimum distance of 4 feet, 6 inches from the western side property line. The maximum height of the barbeque cannot be determined from the submitted application materials.
2. The pool equipment area would be located within the minimum required 25-foot front yard setback for the Minimum Lot Size “-B2” Zoning District, maintaining a minimum distance of 13 feet, 7 inches from the southern front property line. The maximum height of the equipment to be installed cannot be determined from the submitted application materials.
3. The bike shed would be located within the minimum required 25-foot front yard setback for the Minimum Lot Size “-B2” Zoning District, extending 3 feet, 8 inches beyond the front property line. Pursuant to Marin County Code Section 22.130.030 (Definitions of Specialized Terms and Phrases), the floor area of the bike shed would not be included in the calculation of total floor area or total floor area ratio for the subject property. The maximum height of the shed cannot be determined from the submitted application materials.
4. The outward facing retaining wall, situated within the front yard and immediately adjacent to the sports court, would exceed the maximum height of 4 feet above grade established for such walls pursuant to Marin County Code Section 22.20.050(A)(1)(a) (Fencing and Screening Standards), reaching a maximum height of 6 feet above grade.
5. The sport court would be located within the front-yard of the property and would reach a maximum height of 8 feet, 6 inches above grade, calculated pursuant to the height measurement standards for parallel fences and walls established in Marin County Code Section 22.20.050(A)(4) (Parallel Fences and Walls), which accounts for the combined height of the 6-foot retaining wall and the 3-foot, 6-inch guard rail above it. The court would be located within the minimum required 25-foot front yard setback for the Minimum Lot Size “-B2” Zoning District, extending 2 feet, 5 inches beyond the front property line. 

The proposed residential development would include additional improvements to both the residence and the property. Improvements to the residence would include exterior modifications, such as new materials and finishes and changes to fenestration, as well as the construction of an attached accessory dwelling unit (ADU) with an attached porch that would appear to conform to the objective standards for a Category 1 ADU established in Marin County Code Section 22.32.120(A)(1)(C) (Category 1—Statewide Exemption). Improvements to the property would include recreational amenities such as a pool, spa, and outdoor kitchen area; access and hardscaping improvements, including reconfiguration of the parking area and entrance pathway and installation of a new vehicle gate; and landscaping and aesthetic enhancements, including the removal of a heritage coast live oak (Quercus agrifolia) that, according to the submitted arborist report, exhibits structural and health deficiencies and therefore qualifies for removal without permit approval pursuant to Marin County Development Code Section 22.62.040 (Exemptions).

Design Review approval is required pursuant to Sections 22.42.020(B), 22.54.045(F), and 22.32.130(B) of the Marin County Development Code because the project is located on a lot within a Conventional zoning district and would exceed 3,500 square feet of floor area with the proposed development; entails the construction of various detached residential accessory structures (barbeque, pool equipment area, bike shed, and retaining wall) that do not meet applicable height and setback requirements; and proposes a private, non-commercial outdoor sport court accessory to a residential use.

Land Use Info

Zoning: R1-B2 (Residential, Single-Family District, together with the Minimum Lot Size “-B2” Combining District)
Countywide Plan Designation: SF5 (Single-Family 5, Low-Density Residential Designation)
Community Plan (if applicable): Kentfield/Greenbrae Community Plan (1987)