Mill Valley City Zoning Code
CHAPTER 20
16 RS DISTRICTS
§ 20.16.010 Scope of regulations.
The following regulations shall apply with respect to each lot in all RS districts.
§ 20.16.020 Permitted uses.
The following uses are permitted:
A.
One single family dwelling, including transitional and supportive housing structured as single family dwelling;
B.
No more than two roomers per single family dwelling;
C.
Residential facility, small and large;
D.
Home occupation;
E.
Accessory structures;
(Ord. 1182 § 5, April 2, 2002; Ord. 1188 § 7, June 2, 2003; Ord. 1264 § 16, November 3, 2014; Ord. 1331 § 2, November 15, 2021; Ord. 1351, 5/6/2024)
§ 20.16.025 Building permit-Conditions for issuance.
Prior to the issuance of a building permit in any RS-3A, RS-5A and RS-10A zoning district, the Planning Commission shall approve a site development plan fixing the location of all structures, roads, utilities and other improvements including site grading and landscaping.
(Ord. 841 § 3, April 30, 1975)
§ 20.16.030 Conditional uses.
The following uses are permitted subject to the securing of a conditional use permit:
A.
Schools, public and private, including kindergartens, nursery schools and day care centers. The term "day care center," as used in this section, means any institution, boarding home, day nursery or other place required to obtain a license under the provisions of Division 9, Part 4, Chapter 1 of the Welfare and Institutions Code of the State of California;
B.
Church;
C.
Private park or playground;
D.
Public utility structure;
E.
Parking lots when the lot is contiguous to any C district;
(784 § 1, February 20, 1973; Ord. 841 § 4, April 30, 1975; Ord. 1188 § 8, June 2, 2003)
§ 20.16.035 Large family day care homes.
Notwithstanding Sections 20.16.020 and 20.16.030 of this chapter, a large family day care home may be permitted in the RS district pursuant to a use permit issued under the authority of this section.
A.
Standards. The Director of Planning and Building shall issue a use permit to a large family day care home if the day care home meets the following standards and requirements as prescribed by state law:
1.
There shall be a minimum distance of 500 feet between the exterior property line of the site on which the large family day care home is located and the exterior property line of the nearest other licensed large family day care home.
2.
The operation of the large family day care home shall comply with all applicable noise regulations of this Code or the General Plan. The use of amplified music which can be heard from a public right-of-way or neighboring property is prohibited during hours of operation.
3.
In addition to the parking otherwise required for a single family home, one paved parking space, which may be tandem, shall be provided for each nonresident employee, nonresident aide and any other nonresident person engaged in the operation of the day care home. Unless such spaces are located in an existing driveway, such spaces shall be located on the premises outside of the exterior yard setback and shall conform to the requirements of Section 20.60.090 of this title.
4.
There shall be adequate parking for the loading and unloading of children. Loading and unloading shall be on site, or on the street side adjacent to premises. The applicant's driveway shall be sufficient for this purpose provided that the use of the driveway will not block the public right-of-way and all traffic laws are obeyed. Where street parking is available for residential uses, that shall be sufficient for this purpose provided that all traffic and parking regulations are obeyed and double parking is prohibited.
B.
Procedure. An application for a permit to operate a large family day care home shall be filed with the Director of Planning and Building in a form provided by the director. Such application shall be processed pursuant to the following procedures as required by state law.
1.
Notice. Notice of the director's decision to approve or deny a large family day care home shall be mailed, by United States mail, postage prepaid, to the applicants and all owners shown on the last equalized assessment roll as owning real property within 100 feet of the exterior boundaries of the proposed large family day care home 10 days prior to the effective date of the decision.
2.
Hearing. No public hearing on the application shall be held unless a hearing is requested in writing by the applicant or by an affected party owning real property within 100 feet of the exterior boundaries of the proposed large family day care home. The hearing, if requested, shall be conducted by the Zoning Administrator.
3.
Appeal. The applicant or any interested party may appeal the decision of the Director to the Planning Commission.
(Ord. 1215 § 2, November 20, 2006)
§ 20.16.040 Property development regulations.
The following property development regulations shall apply to all permitted uses within RS districts.
A.
Floor Area Calculations. These are the standards applied, along with other applicable development standards in this title and residential design guidelines, to effectively manage the height, bulk and mass of a given project in relation to the lot on which the project stands, in relation to surrounding structures on adjoining properties and in relation to the public realm (streets, sidewalks, open space, etc.).
1.
Adjusted floor area (as defined in Section 20.08.032) for a proposed project will be calculated as follows:
a.
The total gross floor area, measured from the outside faces of the structural walls, of all of the following will be totaled:
i.
All enclosed structures on the lot, including, but not limited to, the main dwelling structure, accessory structures, residential second units, and sheds that require a building permit. Enclosed patios, terraces and balconies are included, but basements, exterior areas under roof eaves or other cantilevered overhangs and non-enclosed spaces (e.g., balconies, decks and porches) or structures (e.g., gazebos and carports) are not included. A space is considered non-enclosed if it is substantially open on at least two sides (sides with guardrails are considered open).
ii.
All enclosed but undeveloped volumes which could be utilized in the future as floor area and have minimum dimensions of eight feet by 10 feet and seven feet headroom without additional excavation. All space horizontally contiguous to this minimum space which maintains at least a width of eight feet and seven feet head room without additional excavation will be included.
b.
The following will be subtracted from subparagraph 20.16.040(A)(1)(a) total above during the renovation or development of a single-family dwelling unit or two-unit project (see Chapter 20.91):
c.
A 50% premium (floor area multiplied by 1.5) will be added for floor area in interior spaces that has a height over 14 feet wherever the 14-foot height measurement is exceeded. The height will be measured as follows.
ii.
On a top floor, wherever the slope of the roof is equal to or greater than a ratio of four feet of rise to 12 feet of run, the height measurement shall be the vertical distance from the finished floor to the roof surface, except any roof surface higher than the midpoint elevation between the elevation of the roof ridge and the elevation of the roof surface at the point directly above the exterior wall surface of the structure shall be ignored and the midpoint elevation shall be considered the top measurement point for this area. If the slope of the roof does not continue linearly to a roof ridge (e.g., as with gambrel and mansard roof styles), then the midpoint elevation will be calculated using the projected intersection of the roof lines as the ridge elevation.
d.
Stair well or elevator shaft floor area shall only be counted once for a building regardless of the number of floors through which the stair well or elevator passes.
2.
The maximum amount of adjusted floor area allowed on a specific lot shall be calculated using the applicable floor area ratio based on effective lot area (as defined in Section 20.08.090) as follows:
3.
During the improvement of an existing single family dwelling, any enclosed but undeveloped volumes may be converted to habitable space and shall not be restricted to the maximum adjusted floor area as determined by Section 20.16.040(A)(2); provided that the conversion of the existing space does not change the existing height, bulk, mass or footprint of the structure and only if minimal excavation or modification of the existing grade is required.
4.
For any existing single family dwelling where the adjusted floor area which existed on May 6, 1991 exceeded or was within 100 square feet of the maximum adjusted floor area specified in this section, a building permit may be obtained for up to 100 square feet of additional floor area where the proposed addition complies with all other provisions of this title (e.g., no variances allowed). This additional floor area will only be available once per parcel.
B.
Maximum Building Height for Dwelling.
Twenty-five feet above natural grade.
Any single family dwelling, or portions of a single family dwelling, with more than twice all required yard setbacks may extend up to 35 feet above the natural grade.
Other exceptions to maximum height: See Section 20.60.060.
C.
Minimum Yard Setbacks.
Exterior: 15 feet.
Interior: One foot for every 1,000 square feet of effective lot area, but no less than five feet or more than 15 feet.
Exceptions to minimum yard setbacks: See Section 20.60.070.
D.
Minimum Lot Size and Width and Maximum Lot Coverage.
Zoning District | Minimum Lot Size * | Minimum Lot Width * | Maximum Lot Coverage % |
|---|---|---|---|
RS-6 | 6000 | 60 | 40 |
RS-7.5 | 7500 | 60 | 40 |
RS-10 | 10000 | 80 | 40 |
RS-15 | 15000 | 80 | 35 |
RS-20 | 20000 | 100 | 35 |
RS-30 | 30000 | 100 | 30 |
RS-43 | 43560 | 150 | 25 |
RS-3A | 3 acres | 150 | 10 |
RS-5A | 5 acres | 150 | 7 |
RS-10A | 10 acres | 150 | 4 |
* | See also Section 21.08.200 for minimum lot area and width requirements for lots with over 10% lot slope. |
(Ord. 1182 § 5, April 2, 2002; Ord. 1258 § 2, October 7, 2013; Ord. 1264 § 17, November 3, 2014; Ord. 1330 § 2, November 15, 2021)