ATHERON MUNICIPAL CODE
PROPOSED AMENDMENTS
SEPTEMBER 18, 2024
Text in Red reflects changing to existing (Black) text.
Chapter 17.30 USE DISTRICTS DESIGNATED
17.30.080 Zoning Overlay Districts
A zoning overlay district allows for specified uses to be developed on lots with an underlying zoning designation. The uses of land allowed by an overlay zone in each zoning district are listed in tables by zoning district category in subsequent chapters of this4 division. For the purposes of this title, the town is divided into the following classes of overlay districts as shown on the maps hereinafter included by reference:
A. Parker Avenue Overlay Districts (P)
B. Multifamily Overlay District (RM-10)
C. Multifamily Overlay District (RM-20/40)
Atherton Municipal Code – Proposed Amendments – September 2024
Chapter 17.32 RESIDENTIAL DISTRICT R1-A
17.32.030 Allowed Uses and Permit Requirements
Table 17.32.030-1 (Allowed Uses and Permit Requirements for Residential District R1A) identifies the allowed uses in the R-1A zoning district subject to the development standards of this chapter and all other provisions of this title. Allowed use provisions are symbolized in the table as follows:
P =Land use permitted by right
CUP=Land use permitted with approval of a conditional use permit Table 17.32.030-1. Allowed Uses and Permit Requirements for Residential District R-1A
Land Use
Zoning District
R-1A
Single-family dwelling1,3 P
Employee housing4 P
Group homes for persons with
disabilities
P
Home occupations P
Mobile and manufactured
housing8
P
Multifamily residential5, 6, 7 P
Second dwelling unit 2 P
Single room occupancy P
Churches and places of worship CUP
Public utilities or facilities CUP
Atherton Municipal Code – Proposed Amendments – September 2024
Notes:
1 Includes associated accessory uses, accessory buildings, and accessory structures (Note: Garages are accessory buildings).
2 Subject to compliance with section 17.32.040 (Development Standards) and chapter 17.52 (Accessory Dwelling Units).
3 Includes residential care facility (defined as a facility serving six or fewer persons).
4 Agricultural employee housing for six (6) or fewer employees shall be treated as a single-family structure pursuant to California Health and Safey Code Section 17021.5.
5 Shall only be permitted on lots with a Multifamily Overlay District (RM-10) designation. Subject to compliance with objective design standards in section 17.36 (Multifamily Overlay District RM-10).
6 Pursuant to Government Code Section 65651, 100% affordable housing that has 25% or 12 units of permanent supportive housing is principally permitted within the multifamily overlay.
7 Pursuant to Government Code Section 65660, a low-barrier navigation center is principally permitted on any parcel within the multifamily overlay. 8 Mobile homes and manufactured housing shall be constructed on a permanent foundation.
Atherton Municipal Code – Proposed Amendments – September 2024
Chapter 17.33 RESIDENTIAL DISTRICT R1-B
17.33.030 Allowed Uses and Permit Requirements
Table 17.33.030-1 (Allowed Uses and Permit Requirements for Residential District R1B) identifies the allowed uses in the R-1B zoning district subject to the development standards of this chapter and all other provisions of this title. Allowed use provisions are symbolized in the table as follows:
P =Land use permitted by right
CUP=Land use permitted with approval of a conditional use permit Table 17.33.030-1. Allowed Uses and Permit Requirements for Residential District R-1B
Land Use
Zoning District
R-1B
Single-family dwelling1,3 P
Employee housing4 P
Group homes for persons with
disabilities
P
Home occupations P
Mobile and manufactured
housing8
P
Multifamily residential5, 6, 7 P
Second dwelling unit 2 P
Single room occupancy P
Churches and places of worship CUP
Public utilities or facilities CUP
Notes:
1 Includes associated accessory uses, accessory buildings, and accessory structures (Note: Garages are accessory structures).
2 Subject to compliance with section 17.33.040 (Development Standards) and chapter 17.52 (Accessory Dwelling Units).
Atherton Municipal Code – Proposed Amendments – September 2024
3 Includes residential care facility (defined as a facility serving six or fewer persons).
4 Agricultural employee housing for six (6) or fewer employees shall be treated as a single-family structure pursuant to California Health and Safey Code Section 17021.5.
5 Mobile homes and manufactured housing shall be constructed on a permanent foundation.
Atherton Municipal Code – Proposed Amendments – September 2024
Chapter 17.34 PARK AND OPEN SPACE DISTRICT (POS)
17.34.030 Allowed Uses and Permit Requirements
Table 17.34.030-1 (Allowed Uses and Permit Requirements for POS District) identifies the allowed uses in the POS district subject to the development standards of this chapter and all other provisions of this title. Allowed use provisions are symbolized in the table as follows:
P =Land use permitted by right
CUP=Land use permitted with approval of a conditional use permit Table 17.34.030-1. Allowed Uses and Permit Requirements for POS District Land Use
Zoning District
POS
Agriculture P
Ecologic study P
Employee housing2 P
Group homes for persons with
disabilities1
P
Multiple-family residential 1 P
Permanent supportive housing1, P
Public park, recreation, or open
space uses
P
Single room occupancy 1 P
Uses of historic and cultural
value
P
Watershed land and
groundwater recharged land
P
Country clubs CUP
Home occupation CUP
Public utilities and facilities
uses and structures
CUP
Caretaker housing CUP
Atherton Municipal Code – Proposed Amendments – September 2024
1 Shall only be permitted on sites with a Multifamily Overlay District (RM-10) designation. Subject to compliance with objective design standards in section 17.XX (Multifamily Overlay District RM-10).
2 Agricultural employee housing must comply with California Health and Safety Code Section 17021.5.
3 Pursuant to Government Code Section 65651, 100% affordable housing that has 25% or 12 units of permanent supportive housing is principally permitted within the multifamily overlay.
4 The Town shall allow by-right a low-barrier navigation center on any parcel with an RM-10 or RM-20/40 overlay designation.
Atherton Municipal Code – Proposed Amendments – September 2024
Chapter 17.36 PUBLIC FACILITIES AND SCHOOLS DISTRICT (PFS)
17.36.030 Allowed Uses and Permit Requirements
Table 17.36.030-1 (Allowed Uses and Permit Requirements for PFS District) identifies the allowed uses in the PFS district subject to the development standards of this chapter and all other provisions of this title. Allowed use provisions are symbolized in the table as follows:
P =Land use permitted by right
CUP =Land use permitted with approval of a conditional use permit L/ER=Land use permitted with location and environmental review Table 17.36.030-1. Allowed Uses and Permit Requirements for PFS District Land Use
Zoning District
PFS
Public library P
Public school P
Town corporation yard P
Town hall and associated
community uses P
Accessory dwelling unit in
conjunction with multifamily
residential uses
P
Emergency shelters P4
Multiple-family residential
uses that accommodate
housing for very low- and lowincome households
associated with primary
nonresidential use of property
on same site
P5
Single room occupancy P5
Churches and places of
worship
CUP
Convents CUP
Atherton Municipal Code – Proposed Amendments – September 2024
Country clubs CUP
Residential associated with
primary nonresidential use of
property on same site1
CUP
Private schools CUP2,3
Public utilities and facilities,
uses, and structures
CUP
Transportation terminal
facilities
CUP
Notes:
1 Examples include dorms or teacher housing associated with school site, convent when associated with religious institutions, etc. and not located on sites with a multifamily overlay.
2 Where a master plan for a private school has been prepared and filed with the town for public record, any application for a conditional use permit shall be compared to the master plan for consistency with that document. All building and/or faculty changes, improvements, or new construction shall require a conditional use permit.
To that end, all conditional use permit applications shall include the following:
a. Maps and diagrams showing the proposal in relation to the master plan layout; b. History of student and faculty growth and projections of future growth, including an analysis of that growth’s consistency with the master plan projections; c. A traffic and parking analysis of the proposal and comparison to the master plan projections;
d. A circulation plan showing how the traffic and pedestrian circulation will function upon implementation of the proposals; and
e. Other information that might be required for specific proposals, such as noise analyses, lighting plans, landscape screening plans, heritage tree locations, and other similar information.
3 In addition to other conditions of approval, the planning commission shall require the following items where relevant:
Atherton Municipal Code – Proposed Amendments – September 2024
a. Identification of the approved uses and hours of operation; and b. Clustering of high intensity or noise-intense structures and uses (such as gymnasiums, theaters, athletic facilities) away from neighboring residential uses, where possible.
4 Emergency shelters shall be permitted only when located within the Town Civic Center property and pursuant to Section 17.36.060; defined as Lots 1, 2, 24, 25 and 26, Watlinton Park RSM (Resubdivision Maps) 5/8.
5 Where a master plan for a private school has been prepared and filed with the town for public record that includes multifamily residential uses that could accommodate housing for very low- and low-income households, such multifamily residential uses shall be subject to planning commission public hearing and review of the location, size, proximity to heritage trees and environmental aspects of the project but shall not result in the denial of the use.
5 Shall only be permitted on sites with a Multifamily Overlay District (RM-20/40) designation. Subject to compliance with objective design standards in section 17.XX (Multifamily Overlay District RM-20/40).
17.36.060 Standards for Emergency Shelter Operation
The objective and predictable standards listed below apply to emergency shelter operations permitted in the PFS District.
A. Size. Emergency shelters shall not exceed one thousand square feet in floor area.
B.A. Beds and Population. The maximum number of client beds permitted in each emergency shelter shall be three fifteen and the maximum client population permitted to be served nightly by the facility shall be threefifteen.
Any additional beds or population shall require a Conditional Use Permit.
C.B. Location. Each emergency shelter shall not be located within a onethousand-foot radius of another emergency shelter.
D.C. Parking. Parking will be provided at a number sufficient to accommodate staff and will not exceed the required parking standards for other uses in the PFS zone. At least one standard size car parking space per emergency shelter bed shall be provided within fifty feet of the emergency shelter.
Atherton Municipal Code – Proposed Amendments – September 2024
E. Waiting and Client Intake Areas. On-site waiting and client intake areas shall be located within the emergency shelter and shall not exceed two hundred fifty square feet in floor area.
F.D. Handicap Accessibility. Each emergency shelter shall be completely handicap accessible.
G. On-Site Management. Space for on-site management shall not exceed five hundred square feet and shall not include more than two beds.
H.E. Exterior Lighting. All exterior lighting shall be shielded or downlit so the source of light is not visible from other properties.
Atherton Municipal Code – Proposed Amendments – September 2024
Chapter 17.XX MULTI-FAMILY OVERLAY DISTRICT (RM-10)
17.XX.010 Purpose.
This chapter establishes development standards for multi-family uses in the residential multi-family overlay zone with a density of up to ten (10) units per acre. The purpose of this chapter is to establish objective criteria for the evaluation of multi-family housing so that it can be permitted by right on specific parcels that are identified in this document and in the Housing Element of the General Plan, or on additional parcels as designated by the City Council.
17.XX.020 Characteristics of the District.
The residential multi-family 10 overlay zone (RM-10) allows multi-family development of up to ten (10) units per acre on parcels zoned for single-family development (R-1A and R-1B), and park and open space (POS).
17.XX.030 Development Standards.
The approval of multi-family development on any parcel in the RM-10 overlay district shall be considered by right when the proposed development is in compliance with these standards. However, this does not preclude other actions that may require discretionary review (i.e. Lot Redesignations, Variances, or Special Structure Permits).
Accessory Buildings and Structures: see chapter 17.40.
A. Height
The maximum height for main buildings shall be thirty-forty (34) feet.
1. Vertical sidewalls and columns built at the setback line shall not exceed thirty (30) feet at the front setback, and twenty-one (21) feet at the side and rear setbacks. Sidewall and column height can exceed these limits with an additional setback that is increased by a ratio of one (1) foot for each one (1) foot increase in height. See figure 17.36.030-1 (Sidewall Height).
2. Height measurement: see chapter 17.42.030.
3. Dormers can exceed the vertical sidewall height and shall be in compliance with development standards in chapter 17.32.040(A)(4)(a and b).
Atherton Municipal Code – Proposed Amendments – September 2024
Figure 17.XX.030-1: Sidewall Height
B. Setbacks
A setback shall be required from all property lines.
There is an additional setback requirement on side and rear property lines that are adjacent to a parcel with an R-1 zoning designation. This requirement shall not apply if the adjacent parcel has an RM-10 overlay designation.
Minimum setback requirements are:
1. Front Yard.
Main building, interior, and corner lots: thirty (30) feet minimum. Where the main building height at the front yard setback is more than thirty (30) feet, the minimum front yard setback shall increase by a ratio of one (1) foot for each one (1) foot increase in height above thirty (30) feet. See figure 17.XX.030-2 (Front Setback).
Atherton Municipal Code – Proposed Amendments – September 2024
Figure 17.XX.030-2: Front Setback
2. Side Yard.
Minimum side yard requirements are shown in Table 17.XX.030.B.2-1; however, where the main building height at the side yard setback is greater than twenty-one (21) feet, the side yard setback shall increase by a ratio of one (1) foot for each one (1) foot increase in height above twenty-one (21) feet. See figure 17.XX.030-3 (Side/Rear Yard Setbacks).
Minimum side yards shall be required on each side of a lot as specified in the following Table:
Table 17.XX.030.B.2-1. Minimum Side Yard Requirements
LOT WIDTH Minimum Side Yard
From To Standard R-1-adjacent*
170’ or over 20’ 40’
165’ 170’ 20’ 38’
160’ 165’ 19’ 36’
155’ 160’ 18’ 34’
150’ 155’ 17’ 32’
145’ 150’ 16’ 30’
140’ 145’ 15’ 28’
140’ or less 15’ 25’
* R-1-adjacent setback does not apply to parcels with an RM-10 overlay designation.
Atherton Municipal Code – Proposed Amendments – September 2024
3. Rear Yard.
Minimum rear yard requirements are shown in Table 17.XX.030.B.3-1; provided, however, where the main building height placed at the setback is between twenty-one (21) and forty (40) feet, the rear yard shall be increased by a ratio of one (1) foot for each one (1) foot increase in height. See figure
17.XX.030-3 (Side/Rear Setbacks).
A minimum rear yard shall be required as specified in the following Table:
Table 17.XX.030.B.3-1. Minimum Rear Yard Requirements
LOT WIDTH Minimum Rear Yard
From To Standard R-1-adjacent*
170’ or over 20’ 50’
165’ 170’ 20’ 47’
160’ 165’ 20’ 44’
155’ 160’ 20’ 41’
150’ 155’ 20’ 37’
145’ 150’ 20’ 33’
140’ 145’ 20’ 29’
140’ or less 20’ 25’
* R-1-adjacent setback does not apply to parcels with an RM-10 overlay designation.
Figure 17.XX.030-3: Side/Rear Setbacks
Atherton Municipal Code – Proposed Amendments – September 2024
C. Floor Area Ratio
The maximum floor area ratio shall be fifty (50) percent of the lot size. Lots with a combining designation of POS shall designate a project site and floor area standards shall be applied. Habitable attic space and below grade parking shall not count towards floor area ratio.
D. Lot Coverage
The maximum lot coverage for buildings, including accessory buildings, shall be forty (40) percent of the lot size. The maximum coverage for all impervious surfaces, not including buildings, shall be twenty (20) percent. The maximum total coverage of all buildings and impervious surfaces shall be fifty (50) percent.
On properties with an underlying POS zoning designation the lot coverage requirement shall apply to any area of the site that facilitates the development of multifamily housing, including ancillary buildings and structures.
Table 17.36.030.C-1
Lot Coverage
Building Impervious Surface Lot
40% 20% 50%
E. Site Design
Requirements for design of the site are:
1. All building entries, including garages and parking areas, shall be connected with a pedestrian pathway that is at least three (3) feet in width.
2. Pedestrian pathways are prohibited within ten (10) feet of a property line adjacent to a parcel with an R-1 zoning designation and no RM-10 overlay.
3. The minimum distance between main buildings on the same lot is twenty (20) feet.
4. Communal outdoor kitchens, pools, and playgrounds shall not be allowed within any setback area.
5. Solid masonry walls or wood fencing shall be provided along all side and rear property lines with a minimum height of eight (8) feet.
6. Vehicle Access.
a. An entry to an underground parking garage is allowed within the front setback. Any grade change resulting from an underground driveway approach shall be set back eight (8) feet from the property line. b. Surface parking shall not be allowed within any setback.
Atherton Municipal Code – Proposed Amendments – September 2024
c. If a vehicle entry gate is provided, it shall be set back from the front property line for a minimum of twenty (20) feet so as to provide a space for vehicle queuing.
d. The maximum driveway width shall be twenty (20) feet and in conformance with minimum requirements for waste and recycling removal.
e. Driveways shall conform to the requirements of the Fire Marshal. f. Driveway visibility. All driveways that intersect with a public right-of-way shall maintain a vision triangle delineated by sides of 10 feet along the right-of-way and 10 feet perpendicular to the right-of-way measured from the edges of the driveway. Within this vision triangle, structures, landscaping, and other obstructions shall have a maximum height of 3 feet. Trees are permitted within the vision triangle provided their canopy maintains a clearance of 6 feet above ground level.
7. Pedestrian Access.
a. A pedestrian entry gate shall be required if a vehicle entry gate is provided.
b. A paved pedestrian pathway shall provide direct access to all entries to a main building and connect with a public pathway.
c. Pedestrian pathways shall be demarcated from driveways with decorative paving materials that include brick, patterned or colored concrete, stone blocks, and pavers.
8. Streetscape Design.
a. A public pathway shall be provided for the full length of the front property line.
b. The pathway shall be a minimum width of five (5) feet. c. The pathway shall meet ADA requirements and be free from obstruction.
d. The pathway shall be designed in compliance with the Bicycle and Pedestrian Master Plan.
e. Any tree removal to accommodate a pathway shall be in compliance with heritage tree protections provided in chapter 8.10.
F. Landscape Screening
All property lines shall provide a landscape screening area in conformance with chapter 17.50 and the standards in this section. Where standards conflict, the most restrictive standard shall apply.
1. Plantings shall be installed within ninety (90) days of the issuance of a building permit.
Atherton Municipal Code – Proposed Amendments – September 2024
2. Plantings shall reach a minimum height of twelve (12) feet within three (3) years of planting.
3. All trees and shrubs shall be evergreen.
4. If the property line is screened with existing landscaping that is at least twelve (12) feet tall and provides opaque screening, no new landscaping is required.
G. Building Massing
Minimum Building Massing requirements are:
1. The maximum aggregate length of all façade segments facing in a common direction shall not exceed one-hundred and twenty (120) feet per building, as measured wall-to-wall. Overlapping wall segments shall not be counted towards the aggregate. See Figure 17.XX.030-4a (Maximum Aggregate Façade Length).
Figure 17.XX.030-4a: Maximum Aggregate Façade Length
2. For any building façade facing the front of a lot and located on or within ten (10) feet of the setback, the maximum aggregate length shall be fifty-five (55) feet. Any portion of the front façade that causes the aggregate length to exceed fifty-five (55) feet shall be set back a minimum of ten (10) feet from the front setback line. See Figure 17.XX.030-4b (Maximum Aggregate Façade on Front Setback).
Atherton Municipal Code – Proposed Amendments – September 2024
Figure 17.XX.030-4b: Maximum Aggregate Façade on Front Setback
3. For any building façade facing the side of a lot and located on or within ten (10) feet of the setback, the maximum aggregate façade length shall be sixtyfive (65) feet. Any portion of the side façade that causes the aggregate length to exceed sixty-five (65) feet shall be set back a minimum of ten (10) feet from the side setback line. See figure 17.XX.030-4c (Maximum Aggregate Façade Length on the Setback).
Figure 17.XX.030-4c: Maximum Aggregate Façade Length on Side Setback Atherton Municipal Code – Proposed Amendments – September 2024
H. Façade Design
Minimum Façade Design requirements are:
1. Primary entries: A primary entry provides access to one or more units from the exterior of a main building and shall not be counted as floor area. A primary entry shall conform to the following standards:
a. Any main building shall be limited to a maximum of four (4) primary entries.
b. Primary entries shall face the lot interior or front property line. c. A maximum of two (2) primary entries can face a public right-of-way. d. A primary entry shall not encroach beyond the setback line, awnings and eaves are exempt from this requirement.
In addition to the standards in H.1, a primary entry shall be designed in accordance with one or more of the five frontage typologies listed in standards H.2 through H.6, below. Frontage typologies can be combined in which case all standards shall apply. If standards contradict, the most restrictive standard shall apply.
2. Common Entry: A common entry provides direct access to a lobby or common space on the ground floor, which provides access to individual units. See figure
17.XX.030-5 (Common Entry).
3. Stoop: A stoop is a small, raised entry that shall provide direct access to no more than two (2) units. A stoop shall conform with the following standards.
See figure 17.XX.030-6 (Stoop).
4. Porch: A porch is a fully covered structure that projects from or is included as part of the main building façade. A porch shall conform with the following standards. See figure 17.XX.030-7 (Porch).
5. Patio: A patio is a private space outside the front door of a unit that is defined by a low wall or hedge extending from the façade. See figure 17.XX.030-8 (Patio).
6. Frontage Court: A frontage court is an open-air space on the building frontage with primary entries oriented to the courtyard interior. A forecourt shall conform with the following standards. See figure 17.XX.030-9 (Frontage Court).
7. Balconies or decks shall not be allowed on walls that face an adjacent property developed with a single-family dwelling, or on portions of any perimeter wall within twenty-five (25) feet of the setback line from an R-1 parcel. Roof decks shall not be permitted. See figure 17.XX.030-10 (Balcony Placement).
Atherton Municipal Code – Proposed Amendments – September 2024
Table 17.XX.030.H.2-1. Common Entry Requirements
Common Entry
Minimum Maximum
Depth 18 inches 4 feet
Width 4 feet 12 feet
Height (Clear) 8 feet 12 feet
Weather protection shall be provided with a projection or recession for a minimum depth of eighteen (18) inches.
Figure 17.XX.030-5: Common Entry
Atherton Municipal Code – Proposed Amendments – September 2024
Table 17.XX.030.H.3-1. Stoop Requirements
Stoop
Minimum Maximum
Depth (Landing) 3 feet 8 feet
Width (Landing) 5 feet 8 feet
Width (Stairs) 4 feet 8 feet
Height (Landing) 1 foot 4 feet
Weather protection shall be provided with a projection or recession for a minimum depth of twelve (12) inches.
Figure 17.XX.030-6: Stoop
Atherton Municipal Code – Proposed Amendments – September 2024
Table 17.XX.030.H.4-1. Porch Requirements
Porch
Minimum Maximum
Depth 8 feet 15 feet
Width 15 feet 40 feet
Width (Stairs) 4 feet 8 feet
Height (Landing) 1 foot 4 feet
Height (Clear) 8 feet 12 feet
The entire porch area shall be covered.
Figure 17.XX.030-7: Porch
Atherton Municipal Code – Proposed Amendments – September 2024
Table 17.XX.030.H.3-1. Patio Requirements
Patio
Minimum Maximum
Depth (Landing) 5 feet 8 feet
Width (Landing) 15 feet 24 feet
Height (Landing) No Minimum 1 foot
Height (Fence/Wall) 1 foot 4 feet
A patio shall provide direct access to no more than two (2) units.
Figure 17.XX.030-8: Patio
Atherton Municipal Code – Proposed Amendments – September 2024
Table 17.XX.030.H.6-1. Frontage Court Requirements
Frontage Court
Minimum Maximum
Depth 15 feet 30 feet
Width 25 feet 40 feet
Height (above grade) No Minimum 1 foot
A frontage court shall provide direct access to no more than four (4) units.
The height of sidewalls facing the courtyard shall not exceed a 2:1 ratio to its depth or width.
Figure 17.XX.030-9: Frontage Court
Figure 17.XX.030-10: Balcony Placement
Atherton Municipal Code – Proposed Amendments – September 2024
8. Minimum Window Detail requirements are:
a. Windows shall be recessed at least two (2) inches from the exterior wall plane to the window glass. See figure 17.XX.030-11 (Window Detail Requirements).
b. Windowsills shall project a minimum of two (2) inches from the surrounding exterior wall plane. See figure 17.XX.030-11 (Window Detail Requirements).
c. All windowsills for non-sleeping rooms facing an R-1 district, located on the second floor or higher, shall be elevated a minimum of fifty-four (54) inches above the finish floor. See figure 17.XX.030-12 (Sill Height). d. Windows shall be vertically oriented and taller than they are wide. e. All privacy windows shall be translucent but not transparent, reflective glass is prohibited.
Figure 17.XX.030-11: Window Detail Requirements
Figure 17.XX.030-12: Sill Height
Atherton Municipal Code – Proposed Amendments – September 2024
I. Façade Material Requirements
The following materials shall be prohibited on any main building façade:
1. An exterior insulation finishing system (EIFS).
2. Aluminum lap siding
3. T1-11 siding
4. Vinyl siding
J. Roof and Eave Details
Minimum Roof and Eave Detail requirements are:
1. Roof eaves may encroach beyond the setback line up to a maximum of four (4) feet on the main building.
2. Roof parapets, when included, shall be a minimum of three (3) feet tall and may not exceed the maximum building height. Roof parapets shall be consistent in material and color with the main building.
3. Asphalt shingles are prohibited.
4. Any equipment placed on the rooftop of a building shall be screened entirely.
K. Site Lighting
Minimum Site Lighting requirements are:
1. No exterior lighting element shall be placed more than height of eight (8) feet above the ground plane unless required by the California Building Code. All exterior lighting shall be directed downward and fully shielded to restrain light to a minimum thirty (30) degrees beneath the horizontal plane of the light source. Lighting shall be arranged so that the light will not shine directly onto any adjacent lot.
2. Up-lighting of trees and permanent lighting within trees is prohibited.
L. Accessory Buildings
Where standards in this section conflict with chapter 17.40, the most restrictive standard shall apply.
1. Accessory Buildings
a. Accessory buildings shall not be allowed in the front setback. Accessory buildings in the side and rear setbacks shall be set back from the property line for a minimum of ten (10) feet. This requirement shall be fifteen (15) feet when adjacent to a parcel with an R-1 zoning designation.
b. A special structures permit shall be required for all sports courts, pools, and outdoor kitchens.
Atherton Municipal Code – Proposed Amendments – September 2024
2. Garages
a. All garages shall be completely enclosed and include a lockable garage door.
b. Materials and colors on garages shall be consistent with the materials and colors utilized on the main building(s).
3. Carports
a. Carports shall be enclosed on three sides.
4. Trash and Recycling Enclosures
a. Trash disposal and recycling areas shall be within an enclosure and shown on the site plan. Trash will be collected on the subject property. b. Each enclosure shall screen trash and recycling receptacles from public view.
c. Trash and recycling enclosures shall be a minimum of eight (8) feet high, constructed of solid wood or masonry painted the same color as the main building(s).
d. Trash and recycling enclosures shall have a gate and a roof. e. Trash and recycling enclosures are not permitted within the front setback.
5. Mailboxes
a. Mailboxes shall be outside of the public right-of-way. b. Projects with six (6) or more dwelling units shall cluster mailboxes in a common centralized location that is part of or within twenty-five feet of a residential building.
M.Parking Requirements
1. Vehicle Parking
Minimum parking requirements are:
a. All resident parking spaces shall be in a garage or below-grade. b. Resident parking spaces shall be provided at a minimum rate of one (1) parking space per bedroom up to a maximum of two (2) spaces per unit.
c. Up to three (3) resident spaces can be provided if all resident parking for the unit is located below grade.
d. Guest parking spaces shall be provided at a minimum rate of fourtenths (0.4) per unit. e. Total resident and guest parking shall not exceed two-and-a-half (2.5) total spaces per unit.
f. Surface parking areas are not permitted within any setback.
2. Bicycle Parking
Minimum bicycle parking requirements are:
Atherton Municipal Code – Proposed Amendments – September 2024
a. Resident bicycle parking shall be provided at a minimum rate of one (1) bicycle parking space per dwelling unit.
b. Bicycle parking facilities shall be located on the ground floor and shall not be located between the building and the street.
c. Bicycle parking that is placed below grade shall not be counted as contributing to the floor area.
Atherton Municipal Code – Proposed Amendments – September 2024
CHAPTER 17.37 MULTI-FAMILY OVERLAY DISTRICT (RM-20/40)
17.37.010 Purpose.
This chapter establishes development standards for multi-family uses in the residential multi-family overlay zone with a density of up to twenty (20) units per acre, and up to forty (40) units per acre, on lots with the RM-20 or RM-40 designation. The purpose of this chapter is to establish objective criteria for the evaluation of multi-family housing so that it can be permitted by right on specific lots that are identified in this document and in the Housing Element of the General Plan, or on additional lots as designated by the City Council.
17.37.020 Characteristics of the District.
The residential multi-family 20 overlay zone (RM-20) allows multi-family development of up to twenty (20) units per acre on identified portions of lots that are zoned as public facilities and schools (PFS) or public open space (POS). Development within the RM-20 district shall have minimum of twelve (12) units per acre.
The residential multi-family 40 overlay zone (RM-40) allows multi-family development of up to forty (40) units per acre on identified portions of the Menlo College Campus (zoned PFS).
Development within the RM-40 district shall have a minimum of twenty-four (24) units per acre.
17.37.030 Development Standards.
The approval of multi-family development on any parcel in the RM-20/40 overlay district shall be considered by right when the proposed development is in compliance with these standards. However, this does not preclude other actions that require discretionary review (i.e. lot redesignations, variances, or special structure permits). Adjoining parcels with a PFS zoning designation and RM-20 or RM-40 zoning overlay can be treated as a single parcel.
Accessory Buildings and Structures: see chapter 17.40.
Atherton Municipal Code – Proposed Amendments – September 2024
A. Height
The maximum height for main buildings shall be forty-eight (48) feet, provided that the vertical midpoint between the eave and the top of roof does not exceed forty-two (42) feet. If the main building has a flat roof, the maximum height is fortytwo (42) feet. See figure 17.XX.030-1 (Maximum Height).
Figure 17.XX.030-1: Maximum Height
1. Vertical sidewalls and columns built at the setback line shall not exceed thirty-four (34) feet. Vertical sidewalls and columns built at the setback line shall not exceed twenty-one (21) feet when facing an adjacent R-1 parcel. Sidewall and column height can exceed these limits with an additional setback that is increased by a ratio of one (1) foot for each one (1) foot increase in height. See figure 17.XX.030-2 (Sidewall Height).
2. Height measurement: see chapter 17.42.030.
3. Dormers can exceed the vertical sidewall height and shall be in compliance with development standards in chapter 17.32.040.(4).
Atherton Municipal Code – Proposed Amendments – September 2024
Figure 17.XX.030-2: Sidewall Height
B. Setbacks
A setback shall be required from all property lines.
Minimum setback requirements are:
1. The minimum spacing between any main buildings shall be twenty (20) feet.
2. General Setbacks:
a. The minimum setback from the property line is twenty (20) feet. See figure 17.XX.030-3A (Setbacks).
b. Where the height of a main building placed at the setback is between thirty-four (34) and forty-eight (48) feet, the setback shall be increased by a ratio of one (1) foot for each one (1) foot increase in height. See figure 17.XX.030-3A (Setbacks).
Atherton Municipal Code – Proposed Amendments – September 2024
Figure 17.XX.030-3A: Setbacks
3. R-1 Adjacent Setbacks:
a. The minimum setback from any property line that is adjacent to a parcel with an R-1 zoning designation shall be thirty (30) feet. See figure
17.XX.030-3B (R-1 Adjacent Setbacks).
b. Where the height of a main building placed at an R-1 adjacent setback is between twenty-one (21) and forty-eight (48) feet, the setback shall be increased by a ratio of one (1) foot for each one (1) foot increase in height. See figure 17.XX.030-3B (R-1 Adjacent Setbacks).
Figure 17.XX.030-3B: R-1 Adjacent Setbacks
Atherton Municipal Code – Proposed Amendments – September 2024
C. Lot Coverage
The maximum lot coverage for buildings, including accessory buildings, shall be forty (40) percent of the lot size. The maximum coverage for all impervious surfaces, not including buildings, shall be twenty (20) percent. The maximum total coverage of all buildings and impervious surfaces shall be fifty (50) percent.
On properties with an underlying PFS zoning designation the lot coverage requirement shall apply to any area of the site that facilitates the development of multifamily housing, including ancillary buildings and structures.
Table 17.XX.030.C-1
Lot Coverage
Building Impervious Surface Lot
40% 20% 50%
D. Site Design
Requirements for design of the site are:
1. Outdoor pools, kitchens, or playgrounds that are ancillary to the residential buildings shall not be allowed within any setback area.
2. Vehicle Access.
a. Direct ingress/egress to below grade parking or an accessory parking structure shall not be allowed on any street that is designated as a highway or a minor arterial in the Atherton General Plan. In lieu of this requirement, then the applicant may provide a traffic study that provides an alternative recommendation which the project implements.
b. Surface parking introduced as part of a new multifamily development shall not be allowed within any setback.
c. Driveway access shall only be provided from a local street, as designated in the Atherton General Plan, or from internal site circulation.
d. The maximum driveway width shall be twenty (20) feet. e. Driveways shall conform to the requirements of the Fire Marshal. f. Driveway visibility. All driveways that intersect with a public right-of-way shall maintain a vision triangle delineated by sides of 10 feet along the right-of-way and 10 feet perpendicular to the right-of-way measured from the edges of the driveway. Within this vision triangle, structures, landscaping, and other obstructions shall have a maximum height of 3 feet. Trees are permitted within the vision triangle provided their canopy maintains a clearance of 6 feet above ground level.
Atherton Municipal Code – Proposed Amendments – September 2024
3. Pedestrian Access.
a. All building entries shall be connected with resident parking areas by a pedestrian pathway that is at least five (5) feet in width. b. Pedestrian pathways are prohibited within ten (10) feet of a property line adjacent to a parcel with an R-1 zoning designation. c. Pedestrian pathways shall be demarcated with decorative paving materials that include brick, patterned or colored concrete, stone blocks, and pavers.
4. Streetscape Design.
a. A public pathway shall be provided for the full length of the site frontage with a street.
b. The pathway shall be a minimum width of five (5) feet. c. The pathway shall meet ADA requirements and be free from obstruction.
d. The pathway shall be designed in compliance with design guidelines provided in section 3.2 of the Bicycle and Pedestrian Master Plan. e. All trees removed to accommodate a pathway shall be replaced. Tree removal shall adhere to heritage tree protections provided in chapter
8.10. E. Landscape Screening
All property lines adjacent to new structures shall be screened according to the standards in chapter 17.50 and the standards in this section. Where standards conflict, the most restrictive standard shall apply.
1. Plantings shall be installed within ninety (90) days from the issuance of a building permit.
2. Plantings shall reach a minimum height of twelve (12) feet within three (3) years of planting.
3. All trees and shrubs shall be evergreen.
4. If the property line is screened with existing landscaping that is at least twelve (12) feet tall and opaque, no new landscaping is required.
F. Building Massing
Minimum Building Massing requirements are:
1. The maximum aggregate façade length: The aggregate length of all façade segments facing in a common direction shall not exceed one-hundred forty (140) feet per building, as measured wall-to wall. See figure 17.XX.030-4A (Maximum Aggregate Façade Length).
Atherton Municipal Code – Proposed Amendments – September 2024
Figure 17.XX.030-4A: Maximum Aggregate Façade Length
2. For any building façade located at the required setback or within ten (10) feet of a required setback, the maximum aggregate façade length shall be sixtyfive (65) feet. Any portion of the façade that causes the aggregate length to exceed sixty-five (65) feet shall be set back a minimum of ten (10) feet from the front setback line. See figure 17.XX.030-4B (Maximum Aggregate Façade on Setback).
Figure 17.37.030-4B: Maximum Aggregate Façade on Setback G. Façade Design
Minimum Façade Design requirements are:
1. Primary entries: A primary entry provides access to one or more units from the exterior of a main building and shall conform to the following standards:
a. A main building shall be limited to a maximum of four (4) primary entries.
Atherton Municipal Code – Proposed Amendments – September 2024
b. No primary entry shall face a highway as designated in the Atherton General Plan.
c. On building sides facing a local street, as designated by the Atherton General Plan, a maximum of three (3) primary entries shall be allowed.
In addition to the standards in G.1, a primary entry shall include one or more of the three frontage typologies listed in standards G.2 through G.4, below:
2. Common Entry: A common entry is a large opening that leads directly into a lobby or common space on the ground floor. A common entry shall comply with the following standards. See figure 17.XX.030-5 (Common Entry).
Table 17.XX.030.G.2-1. Common Entry Requirements
Common Entry
Minimum Maximum
Depth 2 feet 6 feet
Width 8 feet 16 feet
Height (Clear) 8 feet 14 feet
Weather protection shall be provided with a projection or recession with a minimum depth of four (4) feet.
A common entry shall provide access to all units within a main building.
Figure 17.XX.030-5: Common Entry
Atherton Municipal Code – Proposed Amendments – September 2024
3. Stoop: A stoop is a small, raised entry that shall conform with the following standards.
See figure 17.XX.030-6 (Stoop).
Table 17.XX.030.G.3-1. Stoop Requirements
Stoop
Minimum Maximum
Depth (Landing) 3 feet 8 feet
Width (Landing) 5 feet 8 feet
Width (Stairs) 4 feet 8 feet
Height (Landing) 1 foot 4 feet
Weather protection shall be provided with a projection or recession for a minimum depth of twelve (12) inches.
A stoop shall provide direct access to no more than two (2) units.
Figure 17.XX.030-6: Stoop
Atherton Municipal Code – Proposed Amendments – September 2024
4. Frontage Court: A frontage court is an open-air space on the building frontage with primary entries oriented to the courtyard interior. A forecourt shall conform with the following standards. See figure 17.XX.030-7 (Frontage Court).
Table 17.XX.030.G.4-1 Frontage Court Requirements
Frontage Court
Minimum Maximum
Depth 15 feet 30 feet
Width 25 feet 50 feet
Height (above grade) No Minimum 1 foot
A frontage court shall provide direct access to no more than four (4) units.
The height of sidewalls facing the courtyard shall not exceed a 2:1 ratio to its depth or width.
Figure 17.XX.030-7: Frontage Court
Atherton Municipal Code – Proposed Amendments – September 2024
5. Terrace: A terrace is an elevated area for pedestrian circulation along a building frontage that provides access to one or more primary entries. See figure 17.XX.030-8 (Terrace).
Table 17.XX.030.G.5-1 Terrace Requirements
Terrace
Minimum Maximum
Depth 10 feet 24 feet
Height (above grade) 1 foot 3 feet
Height (wall or railing) 30 inches 42 inches
Terrace stairs shall be spaced no more than twenty-five (25) feet apart.
A terrace shall provide direct access to no more than four (4) units.
Figure 17.XX.030-8: Terrace
Atherton Municipal Code – Proposed Amendments – September 2024
6. Balconies or decks shall not be allowed on walls that face an adjacent R-1 parcel, or on portions of any perimeter wall within twenty-five (25) feet of the setback from the R-1 parcel. Roof decks shall not be permitted. See figure 17.XX.030-9 (Balcony Placement).
Figure 17.XX.030-9: Balcony Placement
7. Minimum Window Detail requirements are:
a. Windows shall be recessed at least two (2) inches from the exterior wall plane to the window glass. See figure 17.XX.030-10 (Window Detail Requirements). b. Windowsills shall project a minimum of two (2) inches from the surrounding exterior wall plane. See figure 17.XX.030-10 (Window Detail Requirements).
Figure 17.XX.030-10: Window Detail Requirements
Atherton Municipal Code – Proposed Amendments – September 2024
c. All windowsills for non-sleeping rooms facing an R-1 district, located on the second floor or higher, shall be elevated a minimum of fifty-four (54) inches above the floor plate. See figure 17.XX.030-11 (Sill Height).
Figure 17.XX.030-11: Sill Height
d. Windows shall be vertically oriented and taller than they are wide. e. All privacy windows shall be translucent but not transparent, reflective glass is prohibited.
H. Façade Material Requirements
The following materials shall be prohibited on any main building façade:
1. An exterior insulation finishing system (EIFS).
2. Aluminum lap siding
3. T1-11 siding
4. Vinyl siding
I. Roof and Eave Details
Minimum Roof and Eave Detail requirements are:
1. Roof eaves may encroach into any yard not to exceed a maximum of four (4) feet on the main building.
2. Roof parapets, when included, shall be a minimum of three (3) feet tall and may not exceed the maximum building height. Roof parapets shall be consistent in material and color with the main building.
3. Asphalt shingles are prohibited
4. Any equipment placed on the rooftop of a building shall be screened entirely.
Atherton Municipal Code – Proposed Amendments – September 2024
J. Site Lighting
Minimum Site Lighting requirements are:
1. No exterior lighting element shall be placed above the height of eight (8) feet above the ground plane unless required by the California Building Code. All exterior lighting shall be directed downward and fully shielded to restrain light to a minimum thirty (30) degrees below the horizontal plane of the light source. Lighting shall be arranged so that the light will not shine directly onto any adjacent lot.
2. Up-lighting of trees and permanent lighting within trees is prohibited.
K. Accessory Buildings and Uses
Where standards in this section conflict with chapter 17.40, the most restrictive standard shall apply.
1. Accessory buildings
a. Accessory buildings shall not be allowed in a setback that faces a public right-of-way. Accessory buildings shall be set back from the property line for a minimum of five (5) feet, or a minimum of fifteen (15) feet on a property line that is adjacent to an R-1 parcel.
2. Trash and Recycling Enclosures
a. Trash disposal and recycling areas shall be within an enclosure and shown on the site plan.
b. Each enclosure shall screen trash and recycling receptacles from public view.
c. Trash and recycling enclosures shall be a minimum of eight (8) feet high, constructed of solid wood or masonry painted the same color as the main building(s).
d. Trash and recycling enclosures shall have a gate and a roof. e. Trash and recycling enclosures are not permitted within any setback.
3. Mailboxes
a. Projects with six (6) or more dwelling units shall cluster mailboxes in a common centralized location that is part of or within twenty-five feet of a residential building.
b. Mailboxes shall be located outside of the public right-of-way.
Atherton Municipal Code – Proposed Amendments – September 2024
L. Parking
Minimum Parking requirements are:
1. Vehicle Parking
a. There is no minimum resident or guest parking requirement for housing located within the PFS zone.
b. Total resident and guest parking shall not exceed one-and-a-quarter (1.25) spaces per unit.
c. Total resident and guest parking can be increased to a maximum of two (2) spaces per unit if all the resident and guest parking spaces are provided in a below-grade parking garage.
2. Parking Garage Design
a. No more than twenty-five (25) percent of any ground floor façade shall be dedicated to garage openings.
b. Garaged parking that is above grade shall be screened from a public right-of-way with livable space that has a minimum depth of twenty (20) feet.
c. Partially sub-grade parking shall not have an exposed façade that exceeds five (5) feet above grade and shall provide landscape screening with a minimum depth of ten (10) feet along the entire façade length.
3. Bicycle Parking
Minimum bicycle parking requirements are:
a. Resident bicycle parking shall be provided at a minimum rate of one (1) bicycle parking space per dwelling unit.
b. Bicycle parking facilities shall be located on the ground floor and shall not be located between the building and the street.
c. Bicycle parking that is placed below grade shall not be counted as floor area.