The multi-family residential zones are intended to create and maintain medium and higher density residential neighborhoods that blend a range of housing types with a mix of unit sizes with a limited mix of neighborhood-scale commercial, office, and institutional uses. The City's goals include preservation of the existing stock of rental housing in these areas and provision of opportunities for development of new multi-family housing that increase the diversity of housing options within the City.
The purpose and intent of the City's multiple family zoning districts are as follows:
A. 
Miller Avenue "Passage" District. The Miller Avenue Passage district accommodates medium density residential, including mixed-use with offices or commercial and small-scale multi-family residential developments. Residential land use in these areas is intended to be small- to medium-scale multifamily residential developments, live-work, and mixed-use development.
B. 
Miller Avenue "Parkway" District. The Miller Avenue Parkway district accommodates medium and higher density residential in accordance with the adopted Land Use Map.
C. 
Miller Avenue "Marsh" and "Bayfront" Districts. The Marsh/Bayfront areas accommodate higher density residential, including larger two- to three-story multi-family residential complexes and large-lot condominium and townhouse developments. A major component of the Marsh District is the Red-woods senior housing, which is targeted for an Affordable Housing Overlay Zone to facilitate development of affordable senior housing for the City. The Pickleweed Apartments and Mill Creek Meadows are also located in the Marsh district.
The Bayfront District includes, but is not limited to, the Bayfront, Enchanted Knolls, Shelter Bay, Shelter Hill, and Plymouth Square developments.
(Ord. 1278 § 10, July 18, 2016)
The regulations of this chapter apply to all new development and changes of use within these zoning districts with the exception of existing single family dwellings. Existing single family dwellings in the multi-family residential zones are not considered nonconforming and can be altered and enlarged, if such additions meet the setback, height and other development standards of this Code.
New development and changes of use must meet both the multi-family development standards contained in this chapter as well as the City of Mill Valley Multi-Family Residential Design Guidelines. Additional standards contained throughout this title also apply as noted in "Additional Standards and Provisions" listed in the Use Table in Section 20.24.030.
(Ord. 1278 § 10, July 18, 2016)
The following uses are permitted in the RM-3.5 district:
A. 
One single family dwelling on any single holding of land.
B. 
Multiple family dwellings as shown in the following table:
3.5
1.
Min. land area per dwelling unit (sq. ft.)
3,500
2.
Max. lot coverage (%)
50
3.
Min. yards (setbacks)
 
 
(a) Exterior
15 feet
 
(b) Interior
1 foot per 1,000 sq. ft. of lot area from a minimum of 5 to a maximum of 10 feet
4.
Max. building height:
 
 
(a) At required setbacks to twice all required setbacks
25 feet
 
(b) More than twice all required setbacks
35 feet
5.
Min. usable open space (sq. ft. per dwelling unit)
 
 
(a) 1 or no bedrooms
450
 
(b) 2 bedrooms
450
 
(c) 3 or more bedrooms
450
6.
Densities shall be a minimum of 8 DU/acre and a maximum of 15 DU/acre.
7.
Supportive housing and transitional housing are permitted subject to those restrictions that apply to other residential dwellings of the same type in the same zoning district.
C. 
Residential facility, small.
D. 
Accessory structures.
E. 
A residential second unit as authorized by Chapter 20.90.
(Ord. 872 § 1, August 16, 1976; Ord. 975 § 1, April 20, 1981; Ord. 1093 § 5, March 19, 1990; Ord. 1188 § 10, June 2, 2003; Ord. 1264 § 18, November 3, 2014; Ord. 1278 § 10, July 18, 2016)
The following uses are permitted in the RM-3.5 district subject to the securing of a conditional use permit:
A. 
Office buildings;
B. 
Hospitals, clinics for the treatment of human ailments;
C. 
Funeral parlors;
D. 
Community centers;
E. 
Social halls, lodge and club buildings;
F. 
Horticultural nurseries;
G. 
Residential facility, large;
H. 
Single room occupancy (SRO) dwellings;
I. 
Nursing or rest homes;
J. 
Public utilities structures;
K. 
Day care centers for children;
L. 
Combined residential, commercial and/or business and professional office building;
M. 
Parking lots are permitted in all RM districts on lots contiguous to any C district upon the securing of a conditional use permit.
(Ord. 749 § 1, March 15, 1972; Ord. 865 § 1, April 5, 1976; Ord. 867 § 1, May 17, 1976; Ord. 872 § 2, August 16, 1976; Ord. 1188 § 11, June 2, 2003; Ord. 1264 § 19, November 3, 2014; Ord. 1278 § 10, July 18, 2016)
P = Permitted
CUP = Conditional Use Permit
N = Not permitted
Multi-Family Residential Zones
Bayfront (En. Knolls/Shelter Ridge) (RM-B)
Miller Ave Marsh (RM-M)
Miller Ave Passage (RM-PA)
Miller Ave Parkway (RM-P)
Additional Standards/ Provisions
Residential uses
Rental multi-family housing
P
P
P
P
 
For-sale multi-family housing
P
P
CUP
CUP
See Note 1
Home occupations
P
P
P
P
20.60.250
Accessory structures
P
P
P
P
20.60.075
Single room occupancy (SRO) dwellings
CUP
CUP
CUP
CUP
 
Residential facility, small
P
P
P
P
 
Residential facility, large
 
 
 
 
 
Nursing home
CUP
CUP
CUP
CUP
 
Mixed-use buildings combining residential, commercial, and/or business and professional office building
CUP
CUP
CUP
CUP
 
New single family dwellings
N
N
N
N
See Note 2
Existing single family dwellings
CUP
CUP
CUP
CUP
See Note 2
Live-work
N
N
CUP
CUP
 
Low Barrier Navigation Center
P
P
P
P
As regulated under Government Code Sections 65660-65668
Nonresidential uses
Office buildings
N
CUP
CUP
CUP
 
Hospitals, medical clinic or offices
CUP
CUP
CUP
CUP
 
Funeral parlors
CUP
CUP
CUP
CUP
 
Community centers
CUP
CUP
CUP
CUP
 
Social halls, lodge, or club buildings
CUP
CUP
CUP
CUP
 
Horticultural nurseries
CUP
CUP
CUP
CUP
 
Public utility structures
CUP
CUP
CUP
CUP
 
Day care centers for children
CUP
CUP
CUP
CUP
 
Schools
CUP
CUP
CUP
CUP
 
Public utility structures
CUP
CUP
CUP
CUP
 
Parking lots (not associated w/a use)
CUP
CUP
CUP
CUP
 
Notes:
1.
For-sale housing that is subject to Inclusionary Housing Ordinance (Chapter 20.80) is exempt from conditional use requirement per California Government Code Section 65589.4.
2.
Existing single family residences at the time of the adoption of these regulations shall be considered to be conditionally permitted uses and not be considered "nonconforming uses," and can be altered and enlarged, if such additions meet the setback, height, and other development standards of the single family residential (RS-6) zoning standards (Chapter 20.16).
(Ord. 1278 § 10, July 18, 2016; Ord. 1351, 5/6/2024; Ord. 1354, 9/16/2024)
A. 
Multi-Family Residential Development Base Standards.
Multi-Family Residential Zones
Miller Ave "Marsh" and Bayfront
(RM-M and RM-B)
Miller Avenue "Passage"
(RM-PA)
Miller Avenue "Parkway"
(RM-P)
Minimum Useable Outdoor Living Area (1)
 
 
 
Total required Outdoor Space:
100 s.f. per unit
400 s.f. per unit
400 s.f. per unit
Of required outdoor living space, the minimum Shared Outdoor Space per unit:
50 s.f. per unit for developments over 8 units
200 s.f. per unit for developments over 8 units
200 s.f. per unit for developments over 8 units
Of required outdoor living space, the minimum Private Outdoor Space per unit:
50 s.f.
200 s.f.
200 s.f.
Max. Lot Coverage
50%
45%
45%
Floor Area Ratio (FAR) (1)
Max.= 0.5
Max. = 0.4 for sites over 30,000 s.f.; Max. = 0.6 for sites under 30,000 s.f.
Max. = 0.4 for sites over 30,000 s.f. Max. = 0.6 for sites under 30,000 s.f.
Max. Height (2)
 
 
 
Height
Max. = 35 ft. (3 stories)
Max. = 35 ft. (3 stories)
Max. = 35 ft. (3 stories)
Transitional Height Limit (within 20 feet from abutting single family residential zones)
Max. = 25 ft. (2 stories)
Max. = 25 ft. (2 stories)
Max. = 25 ft. (2 stories)
Stepback (required on all sides above 2nd story)
n/a
1:1 ratio
1:1 ratio
Setbacks (1)
 
 
 
Exterior (front)
Habitable Structures: 15 ft.
Garage: 18 ft. (when not reduced per Section 20.60.080). 18 ft. to face of garage to remain clear.
Habitable Structures: 15 ft.
Garage: 18 ft. (when not reduced per Section 20.60.080). 18 ft. to face of garage to remain clear.
Habitable Structures: 15 ft.
Garage: 18 ft. (when not reduced per Section 20.60.080). 18 ft. to face of garage to remain clear.
Interior (side/rear)
Min. = 5 ft. for sites under 20,000 s.f.; Min.= 10 ft. for sites over 20,000 s.f.;
Min. = 5 ft. for sites under 20,000 s.f.; Min.= 10 ft. for sites over 20,000 s.f.;
Min. = 5 ft. for sites under 20,000 s.f.; Min.= 10 ft. for sites over 20,000 s.f.;
Parking (1, 2)
Parking per Section 20.60.090
Notes:
1.
See Section 20.24.040(B) for additional development standards.
2.
Height exceptions permitted per Section 20.60.060. Dormers, gables, etc. shall be within the stepback height limit.
B. 
Additional Development Standards.
1. 
Efficiency Units. Efficiency units (also known as "micro-units") shall be between 350 and 450 square feet, and shall be limited to 20% of the total units in any individual project site. A minimum of one efficiency unit shall be allowed on any site. Efficiency units shall count as 0.5 unit for purposes of density and parking.
2. 
Duplex. A duplex shall include two primary dwelling units, where either:
a. 
Both units are greater than 1,000 square feet; or
b. 
The square footage ratio between the two units is no greater than 2:3 (for example, if one unit were 900 square feet, the other would need to be at least 600 square feet).
3. 
Useable Outdoor Living Space. Useable outdoor living space shall be a minimum horizontal depth of six feet above the ground level and five feet by 10 feet at the ground level. Required yards less than 10 feet in width adjacent to a building or structure, and areas paved for the storage or movement of motor vehicles or bicycles cannot be considered usable outdoor living space. Accessory buildings or structures may be located within required usable outdoor area when the principal uses of such buildings or structures are accessory to those of the usable outdoor areas within which they are located.
4. 
Adjusted Floor Area—Parking Exclusions. The first 250 square feet of garage space for each parking space is excluded from the allowable FAR. Underground or partially underground parking is exempt from the FAR calculations if it meets the Basement definition in Section 20.08.038.
5. 
Reduced Standards for Narrow Lots. For lots 25 feet wide or less, the following shall apply:
a. 
Interior side and rear setbacks for lots of 25 feet or less in width is a minimum of three feet. A minimum five-foot setback will remain where windows are placed along the setback line. The five-foot setback will apply to the window and a five-foot section of the building wall on each side of the window. Exterior walls along the minimum setback line shall include a recess or offset of at least two feet for every 35 feet of wall (for a minimum of five feet).
b. 
Lots of 25 feet or less in width shall provide parking per dwelling unit as specified in Section 20.60.090(I)(7), but shall not be required to provide guest parking per Section 20.60.090(B)(7).
(Ord. 1278 § 10, July 18, 2016)