Atherton City Zoning Code

Division II

Districts and Development Standards

17.30.010 Designation of Districts.

For the purposes of this title, the town is divided into the following classes of districts as shown on the maps hereinafter included by reference:

A. Residential district R-1A.

B. Residential district R-1B.

C. Parks and open space district (POS District).

D. Public facilities and school district (PFS District). (Ord. 582 § 1 (Exh. A), 2009)

17.30.020 Zoning Plan.

The designations, locations, and boundaries of the districts established are delineated on the map entitled “Atherton Zoning Plan,” dated as amended from time to time. This zoning map and all notations and information thereon are made a part of this chapter by reference. (Ord. 630 § 1, 2018; Ord. 582 § 1 (Exh. A), 2009)

17.30.030 Allowed Uses Generally.

Land use provisions are established in this title by the zoning district applied to a site. The uses of land allowed in each zoning district are listed in tables by zoning district category in subsequent chapters of this division. Permitted or conditional uses listed in the various district regulations are specific and no other uses shall be allowed. (Ord. 582 § 1 (Exh. A), 2009)

17.30.040 Similar Use Determination.

When a use is not specifically listed in this title, the planning commission may determine that the use is similar to a listed use by following the conditional use procedure specified in chapter 17.12 (Conditional Use Permit). Such similar use shall be categorized as a conditional use. In making such a determination, the planning commission shall make all of the following findings:

A. The proposed use will be consistent with the general plan.

B. The proposed use will be consistent with the purposes of the applicable zoning district.

C. The characteristics of and activities associated with the proposed use are equivalent to one or more of the listed uses and will not have a higher level of activity or population density than the uses listed in the district. (Ord. 582 § 1 (Exh. A), 2009)

17.30.050 Certain Commercial-Residential Uses Prohibited.

No new commercial-residential uses are permitted anywhere in the Town of Atherton. Such prohibited uses include hotels, motels, boardinghouses, and transient guest quarters, including bed and breakfasts. (Ord. 582 § 1 (Exh. A), 2009)

17.30.060 Interpretation of District Boundaries.

Whenever any uncertainty exists as to the boundary of any district shown on the zoning plan, it shall be the responsibility of the town planner to interpret the boundaries of the district. In making such a determination, the following rules shall apply:

A. When a boundary line is indicated as following a street or similar right-of-way, it shall be interpreted as following the centerline of that right-of-way.

B. Where a boundary line is indicated as approximately following a lot line, the boundary line shall be interpreted to follow that lot line.

C. Where a boundary line divides a lot or crosses unsubdivided property, the location of such boundary shall be interpreted as being the closest lot line. (Ord. 582 § 1 (Exh. A), 2009)

17.30.070 Legal Lots.

Any existing lot, legally created, may be used for uses allowed in the district even if it does not meet the current building site area or dimension standards established in title 16 (Subdivisions). All new lots shall be consistent with the development standards in chapter 16.24 (Design). No subdivision shall be approved that would increase the nonconformity of an existing parcel or any nonconforming use on the parcel. (Ord. 582 § 1 (Exh. A), 2009)

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 this 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). (Ord. 669 § 4, 2024)

17.32.010 Purpose.

This chapter identifies the allowed use and permit requirements and development standards for the residential district R-1A. The intent of this district is to implement the residential land use categories of the town’s general plan. It is designed to designate land for the development of residential uses consistent with the development regulations set forth in this title. (Ord. 582 § 1 (Exh. A), 2009)

17.32.020 Characteristics of the District.

Residential district R-1A provides for the development of single-family residential uses at a density of one dwelling unit per lot. It allows for new subdivisions with a minimum lot size of one acre. Second dwelling units are permitted, consistent with the development standards of this title. Home occupations are also appropriate for this district, consistent with the development standards of this title. Other uses, including churches and public utilities and facilities, may be allowed upon issuance of a conditional use permit. (Ord. 582 § 1 (Exh. A), 2009)

17.32.030 Allowed Uses and Permit Requirements.

Table 17.32.030-1 (Allowed Uses and Permit Requirements for Residential District R-1A) 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

Land Use	Zoning District
Land Use	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 unit²	P
Single-room occupancy	P
Churches and places of worship	CUP
Public utilities or facilities	CUP

1Includes associated accessory uses, accessory buildings, and accessory structures (Note: Garages are accessory buildings).

2Subject to compliance with section 17.32.040 (Development Standards) and chapter 17.52 (Accessory Dwelling Units).

3Includes residential care facility (defined as a facility serving six or fewer persons).

4Agricultural employee housing for six or fewer employees shall be treated as a single-family structure pursuant to California Health and Safety Code Section 17021.5.

5Shall only be permitted on lots with a Multifamily Overlay District (RM-10) designation. Subject to compliance with objective design standards in chapter 17.35 (Multifamily Overlay District RM-10).

6Pursuant to Government Code Section 65651, a one hundred percent affordable housing development that provides twenty-five percent of its total units, or twelve units, as permanent supportive housing, is principally permitted within the multifamily overlay.

7Pursuant to Government Code Section 65660, a low-barrier navigation center is principally permitted on any parcel within the multifamily overlay.

8Mobile homes and manufactured housing shall be constructed on a permanent foundation.

(Ord. 669 § 4, 2024; Ord. 591 § 9, 2010; Ord. 582 § 1 (Exh. A), 2009)

17.32.040 Development Standards.

The following minimum and maximum requirements shall apply in the R-1A district. The town planner will review development applications against these standards to determine compliance with applicable zoning regulations.

A. Height. The maximum building heights permitted are provided below. See also chapter 17.42 for height measurement.

1. The standard maximum height for main buildings shall be thirty feet; provided, that vertical sidewalls and columns may not exceed twenty-two feet; and provided further, that these standard maximum heights may be increased, but in no event to exceed thirty-four feet for main buildings nor to exceed twenty-eight feet for vertical sidewalls and columns, as follows:

a. The main building, vertical sidewalls, and columns height may be increased in any case where the front, rear, and side yards as measured to the area(s) having the increased vertical height, are increased above the standard setbacks by a ratio of at least five feet for each one-foot increase of height; and

b. Increased height for a main building (but not to exceed thirty-four feet) or for vertical sidewalls or columns (but not to exceed twenty-eight feet) shall be permitted upon approval of a special structure permit.

2. Accessory structures: see chapter 17.40.

3. Detached garages: see chapter 17.40.

4. Consistent with the sidewall height limit for the R-1A zone, dormers that exceed or are otherwise built above the sidewall height limit for the structure, as measured from the extension of the eave line across the width of the dormer, shall be developed consistent with the following standards (see figures 17.32.040-1a (Dormers) and 17.32.040-1b (Excessive Dormers)).

a. The maximum combined length of all dormers on a side or elevation of a building shall not exceed fifty percent of the total length of the respective side or elevation of the building to which they are associated (see figure 17.32.040-1b (Excessive Dormers)).

b. The face of the dormer shall be a minimum of two feet below the ridge line (see figure 17.32.040-2 (Dormer Height and Placement)).

B. Lot Size Requirements. New lots created in the R-1A district shall be consistent with the lot size requirements established in section 16.24.050 (Lot Size Requirements).

C. Maximum Floor Area Ratio. The maximum floor area ratio shall be eighteen percent of the lot size except for those lots smaller than forty-three thousand five hundred sixty square feet (one acre), which shall be determined by the following equation:

Floor area in square feet = (lot size in square feet × 0.163) + 726 square feet, with a minimum allowable floor area of 2,250 square feet.

The floor area above the first floor of the main building for all lots shall not exceed seven and one-half percent of the lot size.

The following conditions shall not be included in floor area calculations:

1. Structures, open on all sides, with substantially open roofs (e.g., trellis) (see figure 17.32.040-3 (Substantially Open Roof)), with the following provisions:

a. No more than one side of the structure shall be attached to the main building and no more than one side of the structure may be enclosed by small structural features (e.g., outdoor kitchens/barbeques, fire pits/fireplaces, cabinets); provided, that on the side with the structural feature at least fifty percent of the side is still open (see figure 17.40.040-2 (Attached Trellis Exempt from Floor Area Requirement); or

b. No more than two sides shall be partially enclosed with small structural features (e.g., outdoor kitchens/barbeques, fire pits/ fireplaces, cabinets); provided, that at least fifty percent of both sides is still open and the other two sides are completely open; and

2. Roofed areas completely open on two or more sides up to five percent of the maximum allowed floor area for the lot plus five hundred square feet (e.g., awning, patio cover, covered walk).

D. Front and Rear Yards. Minimum front and rear yard requirements are:

1. Main building, interior, and corner lots: sixty feet minimum; provided, however, on lots of record prior to adoption of Ordinance No. 146 (April 16, 1946) with a depth of less than two hundred feet, the front and rear yards shall each be thirty percent of the lot depth with a minimum of thirty feet; provided further, where main building heights are between thirty feet and thirty-four feet, the front and rear yards shall be increased by a ratio of five feet for each one-foot increase in height.

2. Accessory structures: as provided in chapter 17.40.

3. The property owned by the City and County of San Francisco, known as the Hetch Hetchy property, over which the owner of adjacent property with contiguous frontage has reserved surface rights, may be utilized by the adjacent property owner for setback calculation purposes. The adjacent property owner may calculate setbacks to the original property line prior to the acquisition by the City and County of San Francisco, or, in the case of properties subdivided after that date, to the centerline of the Hetch Hetchy property.

4. Second Dwelling Units. As provided in chapter 17.52.

E. Side Yards. Minimum side yard requirements are as shown in Table 17.38.010; provided, however, where main building heights are between thirty feet and thirty-four feet with the issuance of a special structure permit, the side yards shall be increased by a ratio of five feet for each one-foot increase in height.

1. The property owned by the City and County of San Francisco, known as the Hetch Hetchy property, over which the owner of adjacent property with contiguous frontage has reserved surface rights, may be utilized by the adjacent property owner for setback calculation purposes. The adjacent property owner may calculate setbacks to the original property line prior to the acquisition by the City and County of San Francisco, or, in the case of properties subdivided after that date, to the centerline of the Hetch Hetchy property.

2. Second Dwelling Units. Minimum side yard requirements are as provided in chapter 17.52.

F. Accessory Structure Area. Maximum area permitted for all accessory structures, exclusive of pools, tennis courts, garages, carports, drives, and other paved surfaces, on a building site shall not exceed the ratio of one thousand two hundred square feet of accessory structure for each forty-three thousand five hundred sixty square feet of lot area.

G. Eaves. Roof eaves may encroach into any yard not to exceed a maximum of four feet on the main building and not to exceed one foot on an accessory building.

1. There is no limitation on the maximum number of kitchens for the main dwelling.

2. One kitchen may be within an approved second dwelling unit that is located within the main dwelling building setback lines. (Ord. 627 § 1, 2017; Ord. 591 §§ 2, 3, 2010; Ord. 582 § 1 (Exh. A), 2009)

17.33.010 Purpose.

This chapter identifies the allowed use and permit requirements and development standards for the residential district R-1B. The intent of this district is to implement the residential land use categories of the town’s general plan. It is designed to designate land for the development of residential uses consistent with the development regulations set forth in this title. (Ord. 582 § 1 (Exh. A), 2009)

17.33.020 Characteristics of the District.

Residential district R-1B provides for the development of single-family residential uses at a density of one dwelling unit per lot. It allows for new subdivisions with a minimum lot size of one acre. Second dwelling units are permitted, consistent with the development standards of this title. Home occupations are also appropriate for this district, consistent with the development standards of this title. Other uses, including churches and public utilities and facilities, may be allowed upon issuance of a conditional use permit. (Ord. 582 § 1 (Exh. A), 2009)

17.33.030 Allowed Uses and Permit Requirements.

Table 17.33.030-1 (Allowed Uses and Permit Requirements for Residential District R-1B) 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

Land Use	Zoning District
Land Use	R-1B
Single-family dwelling¹^,³	P
Employee housing⁴	P
Group homes for persons with disabilities	P
Home occupations	P
Mobile and manufactured housing⁵	P
Second dwelling unit²	P
Single-room occupancy	P
Churches and places of worship	CUP
Public utilities or facilities	CUP

1Includes associated accessory uses, accessory buildings, and accessory structures (Note: Garages are accessory structures).

2Subject to compliance with section 17.33.040 (Development Standards) and chapter 17.52 (Accessory Dwelling Units).

3Includes residential care facility (defined as a facility serving six or fewer persons).

4Agricultural employee housing for six or fewer employees shall be treated as a single-family structure pursuant to California Health and Safety Code Section 17021.5.

5Mobile homes and manufactured housing shall be constructed on a permanent foundation.

(Ord. 669 § 4, 2024; Ord. 591 § 10, 2010; Ord. 582 § 1 (Exh. A), 2009)

17.33.040 Development Standards.

The following minimum and maximum requirements shall apply in the R-1B district. The town planner will review development applications against these standards to determine compliance with applicable zoning regulations.

A. Height. The maximum building heights permitted are provided below. See also chapter 17.42 for height measurement.

1. Main buildings: twenty-eight feet; provided, that neither vertical side walls or columns exceed eighteen feet. End walls shall be perpendicular to the lot depth.

2. Accessory structures: see chapter 17.40.

3. Detached garages: see chapter 17.40.

4. Consistent with the sidewall height limit for the R-1B zone, dormers that exceed or are otherwise built above the sidewall height limit for the structure, as measured from the extension of the eave line across the width of the dormer, shall be developed consistent with the following standards (see figures 17.33.040-1a (Dormers) and 17.33.040-1b (Excessive Dormers)).

b. The face of the dormer shall be a minimum of two feet below the ridge line (see figure 17.33.040-2 (Dormer Height and Placement)).

B. Lot Size Requirements. New lots created in the R-1B district shall be consistent with the lot size requirements established in section 16.24.050 (Lot Size Requirements).

C. Maximum Floor Area Ratio. The maximum floor area ratio shall be eighteen percent of the lot size except for those lots smaller than forty three thousand five hundred sixty square feet (one acre), which shall be determined by the following equation:

Floor area in square feet = (lot size in square feet × 0.165) + 1,500 square feet.

The following conditions shall not be included in floor area calculations:

1. Structures, open on all sides, with substantially open roofs (e.g., trellis) (see figure 17.33.040-3 (Substantially Open Roof)), with the provisions of subsections (C)(2)(a) and (b) of this section.

2. Roofed areas open on two or more sides not exceeding five percent of the maximum allowed floor area for the lot plus five hundred square feet (e.g., awning, patio cover, covered walk), with the provisions of subsections (C)(2)(a) and (b) of this section.

D. Front and Rear Yards. Minimum front and rear yard requirements are:

1. Main buildings, interior and corner lots: thirty feet minimum; provided, however, on lots of record prior to adoption of Ordinance No. 277 (October 30, 1967) with a depth less than one hundred sixty feet, the front and rear yards shall each be eighteen percent of the lot depth with a minimum of twenty feet; and

2. Accessory structures, as provided in chapter 17.40.

3. Second Dwelling Units. As provided in chapter 17.52.

E. Side Yards. Minimum side yard requirements are as shown in Table 17.38.010.

1. Second Dwelling Units. Minimum side yard requirements are as provided in chapter 17.52.

F. Eaves. Roof eaves may encroach into any yard not to exceed a maximum of four feet on the main building and not to exceed one foot on an accessory building.

1. There is no limitation on the maximum number of kitchens for the main dwelling.

2. One kitchen may be within an approved second dwelling unit. (Ord. 591 §§ 4—6, 2010; Ord. 582 § 1 (Exh. A), 2009)

17.34.010 Purpose.

The purpose of this chapter is to implement the open space element of the general plan and provisions of the California Government Code related to open space zoning. This district is designed to designate open space for the preservation of natural resources, uses for the managed production of resources, for outdoor recreation, and for public health and safety. Compliance with the California Government Code requirements for an open space zoning code is achieved through use of this district.

The regulations set forth in this chapter shall apply in all park and open space (POS) districts and shall be subject to the provisions of this title. (Ord. 582 § 1 (Exh. A), 2009)

17.34.020 Characteristics of the District.

The POS district provides for the establishment of parks, recreation, and open space uses. Other recreational and natural preservation uses, such as country clubs, watershed protection lands, and similar uses, may be permitted. (Ord. 582 § 1 (Exh. A), 2009)

17.34.030 Permitted Uses.

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

Land Use	Zoning District
Land Use	POS
Agriculture	P
Ecologic study	P
Employee housing²	P
Group homes for persons with disabilities¹	P
Multifamily residential¹^, ⁴	P
Permanent supportive housing¹^, ³	P
Public park, recreation, or open space uses	P
Single-room occupancy¹	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

1Shall only be permitted on lots with a Multifamily Overlay District (RM-10) designation. Subject to compliance with objective design standards in chapter 17.35 (Multifamily Overlay District RM-10).

2Agricultural employee housing must comply with California Health and Safety Code Section 17021.5.

3Pursuant to Government Code Section 65651, a one hundred percent affordable housing development that provides twenty-five percent of its total units, or twelve units, as permanent supportive housing, is principally permitted within the multifamily overlay.

4Pursuant to Government Code Section 65660, a low-barrier navigation center is principally permitted on any parcel within the multifamily overlay.

(Ord. 669 § 4, 2024; Ord. 582 § 1 (Exh. A), 2009)

17.34.040 Development Standards.

Table 17.34.040-1 (Development Standards for POS District) identifies the development standards for the POS district. All buildings and structures located in the POS district shall be considered as main buildings and not as accessory structures.

Development Standard	Zoning District
Development Standard	POS
Height, maximum	34 ft.
Lot coverage, aggregate, maximum	20% gross lot area
Front and rear yard, minimum	60 ft.
Side yard, minimum	See chapter 17.38

(Ord. 582 § 1 (Exh. A), 2009)

17.35.010 Purpose.

This chapter establishes development standards for multifamily uses in the residential multifamily overlay zone with a density of up to ten units per acre. The purpose of this chapter is to establish objective criteria for the evaluation of multifamily housing so that it can be permitted by right on specific parcels that are identified in this chapter and in the Housing Element of the General Plan, or on additional parcels as designated by the City Council. (Ord. 669 § 4, 2024)

17.35.020 Characteristics of the District.

The residential multifamily 10 overlay zone (RM-10) allows multifamily development of up to ten units per acre on parcels zoned for single-family development (R-1A), and park and open space (POS). To apply the standards within the RM-10 overlay zone a development must have a minimum lot area of one-half acre and include a minimum of five residential units exclusive of accessory dwelling units. Parcels zoned as POS shall be exempt from the minimum unit and lot area requirements. (Ord. 669 § 4, 2024)

17.35.030 Development Standards.

The approval of multifamily 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-four feet.

1. Vertical end walls, sidewalls, and columns shall not exceed twenty-eight feet when facing the front setback, and twenty-one feet when built at the side and rear setback lines. See figure 17.35.030-1 (Sidewall Height).

2. On side and rear setbacks only, the end wall, sidewall, or column height can exceed the limit with an additional setback that is increased by a ratio of one foot for each one foot increase in height. See figure 17.35.030-1 (Sidewall Height).

3. Height Measurement. See section 17.42.030.

4. Dormers can exceed the vertical sidewall height and shall be in compliance with development standards in sections 17.32.040(A)(4)(a) and (A)(4)(b).

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 and is developed with a multifamily dwelling or has an active application for development of a multifamily dwelling.

Minimum setback requirements are:

1. Front Yard. Main building, interior, and corner lots: thirty feet minimum. Where the main building height at the front yard setback is more than twenty-eight feet, the minimum front yard setback shall increase by a ratio of one foot for each one foot increase in height above twenty-eight feet. See figure 17.35.030-2 (Front Setback).

Up to ten feet may be subtracted from the front yard required setback if an identical amount is added to the required rear yard setback.

On corner lots where two or more property lines face a public right-of-way, the property line with the greater length shall be considered the front.

2. Side Yard. Minimum side yard requirements are shown in Table 17.35.030.B.2-1; however, where the main building height at the side yard setback is greater than twenty-one feet, the side yard setback shall increase by a ratio of one foot for each one foot increase in height above twenty-one feet. See figure 17.35.030-3 (Side/Rear Yard Setbacks).

Minimum side yards shall be required on each side of a lot as specified in the following Table:

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 and existing or proposed multifamily development.

3. Rear Yard. Minimum rear yard requirements are shown in Table 17.35.030.B.3-1; provided, however, where the main building height placed at the setback is between twenty-one and thirty-four feet, the rear yard shall be increased by a ratio of one foot for each one foot increase in height. See figure 17.35.030-3 (Side/Rear Setbacks).

A minimum rear yard shall be required as specified in the following Table:

LOT WIDTH		Minimum Side Yard
From	To	Standard	R-1-adjacent*
170’ or over		20’	50’
165’	170’	20’	48’
160’	165’	20’	46’
155’	160’	20’	44’
150’	155’	20’	42’
145’	150’	20’	40’
140’	145’	20’	38’
140’ or less		20’	35’
* R-1-adjacent setback does not apply to parcels with an RM-10 overlay designation and existing or proposed multifamily development.

C. Floor Area Ratio. The maximum floor area ratio shall be forty-five hundredths of the lot size. The floor area ratio can be increased up to an additional one-tenth of the lot size, to a total of fifty-five hundredths, if all resident parking is below grade. Lots with a combining designation of POS shall designate a project site and floor area standards shall be applied. Below-grade parking shall not count towards the floor area ratio. Habitable basement space shall not count towards the floor area ratio; provided, that one hundred percent of resident parking is located fully below-grade.

D. Lot Coverage. The maximum lot coverage for buildings, including accessory buildings, shall be forty percent of the lot size. The maximum coverage for all impervious surfaces, not including buildings, shall be twenty percent. The maximum total coverage of all buildings and impervious surfaces shall be fifty percent.

All parts of the lot not covered by buildings or impervious surfaces shall be covered by landscape area. All landscape areas shall be maintained reasonably free of weeds, litter, and debris. All planting shall be maintained in a healthy growing condition and, whenever necessary, replaced with plant materials approved by the town arborist to provide continued conformance with approved plans. All new screening plantings shall be provided with a water-efficient automatic irrigation system to be installed at the time of planting. Landscape areas shall not interfere with heritage tree protection.

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.

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 feet in width.

2. Pedestrian pathways are prohibited within ten feet of a property line adjacent to a parcel with an R-1 zoning designation or a single-family dwelling in an RM-10 overlay, with no active proposal for multifamily housing.

3. The minimum distance between main buildings on the same lot is twenty feet.

4. Communal outdoor kitchens, pools, and playgrounds are allowed within the buildable area. Location of these features in required setback areas may be sought through a special structures permit.

5. Solid masonry walls or wood fencing shall be provided along all side and rear property lines with a height of eight feet.

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 ten feet from the property line.

b. Surface parking is allowed within the front and side setbacks.

c. If a vehicle entry gate is provided, it shall be set back from the front property line for a minimum of twenty feet so as to provide a space for vehicle queuing.

d. The maximum driveway width shall be twenty-six 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 ten feet along the right-of-way and ten 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 three feet. Trees are permitted within the vision triangle provided their canopy maintains a clearance of six feet above ground level.

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.

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 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. Prior to the final inspection or issuance of a certificate of occupancy (unless delay is authorized by the building official) all required landscape screening shall be installed in conformance with the approved plans. In the case of phased building construction, the town building official may permit phased installation of landscape screening. No other exception to this installation requirement shall be allowed, including any in lieu fee or deposit.

2. Plantings shall reach a minimum height of twelve feet within three 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 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 feet per building, as measured wall-to-wall. Overlapping wall segments shall not be counted towards the aggregate. See figure 17.35.030-4a (Maximum Aggregate Façade Length).

Figure 17.35.030-4a. Maximum Aggregate Façade Length

2. For any building façade facing the front of a lot and located on or within ten feet of the setback, the maximum aggregate length shall be fifty-five feet. Any portion of the front façade that causes the aggregate length to exceed fifty-five feet shall be set back a minimum of ten feet from the front setback line. See figure 17.35.030-4b (Maximum Aggregate Façade on Front Setback).

Figure 17.35.030-4b. Maximum Aggregate Façade on Front Setback

3. For any building façade facing the side of a lot and located on or within ten feet of the setback, the maximum aggregate façade length shall be sixty-five feet. Any portion of the side façade that causes the aggregate length to exceed sixty-five feet shall be set back a minimum of ten feet from the side setback line. See figure 17.35.030-4c (Maximum Aggregate Façade Length on Side Setback).

Figure 17.35.030-4c. Maximum Aggregate Façade Length on Side Setback

4. Locations for Basements. The basement perimeter shall not exceed the buildable area defined by the setbacks of the lot. This shall include any below grade area used for vehicle parking. Construction of the basement shall not cause the removal or disturbance of any heritage tree located in a setback.

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 primary entries.

b. Primary entries shall face the lot interior or front property line.

c. A maximum of two 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 subsection (H)(1) of this section, a primary entry shall be designed in accordance with one or more of the five frontage typologies listed in standards in subsections (H)(2) through (H)(6) of this section. 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 17.35.030-5 (Common Entry).

3. Stoop. A stoop is a small, raised entry that shall provide direct access to no more than two units. A stoop shall conform with the following standards. See figure 17.35.030-6 (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 17.35.030-7 (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 17.35.030-8 (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 17.35.030-9 (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 feet of the setback line from an R-1 parcel. Roof decks shall not be permitted. See figure 17.35.030-10 (Balcony Placement).

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 inches.

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 inches.

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.

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 units.

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 units. The height of sidewalls facing the courtyard shall not exceed a 2:1 ratio to its depth or width.

8. Minimum Window Detail requirements are:

a. Windows shall be recessed at least two inches from the exterior wall plane to the window glass. See figure 17.35.030-11 (Window Detail Requirements).

b. Windowsills shall project a minimum of two inches from the surrounding exterior wall plane. See figure 17.35.030-11 (Window Detail Requirements).

c. All windowsills for nonsleeping rooms facing an R-1 district, located on the second floor or higher, shall be elevated a minimum of fifty-four inches above the finish floor. See figure 17.35.030-12 (Sill Height).

d. Any window facing an R-1 district, located on the second floor or higher, shall be translucent but not transparent for any part of the window glass less than fifty-four inches above the finish floor.

e. Windows shall be vertically oriented and taller than they are wide.

f. All privacy windows shall be translucent but not transparent; reflective glass is prohibited.

Figure 17.35.030-11. Window Detail Requirements

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 feet on the main building.

2. Roof parapets, when included, shall be a minimum of three feet tall and may not exceed the maximum building height. Roof parapets shall be consistent in material and color with the main building.

3. 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 a height of eight 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 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.

3. Interior lighting of all common areas shall be controlled by motion detecting controls programed to turn off no more than five minutes after movement is no longer detected by the controlling device. Interior “common areas” are spaces used by multiple units generally for circulation purposes having exterior-facing windows.

L. Accessory Buildings and Structures. Where standards in this section conflict with chapter 17.40, the most restrictive standard shall apply.

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 feet. This requirement shall be fifteen feet when adjacent to a parcel with an R-1 zoning designation or an RM-10 property that is developed with a single-family dwelling and does not have an active proposal to construct multifamily housing.

b. Communal outdoor kitchens, pools, and playgrounds are allowed within the buildable area. Location of these features in required setback areas may be sought through a special structures permit.

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).

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 six feet and a maximum of eight feet in height. The enclosure shall be 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.

a. Mailboxes shall be outside of the public right-of-way.

b. Projects with six 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.

1. Vehicle Parking. Minimum parking requirements are:

a. Surface parking shall be enclosed on three sides by landscape screening that is more than three feet from the perimeter of the parking area and comprised of plants with a minimum expected height of eight feet within three years of planting.

b. Resident parking spaces shall be provided at a minimum rate of one parking space per bedroom up to a maximum of two spaces per unit.

c. Up to three resident spaces per unit 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 four-tenths per unit.

e. Total resident and guest parking shall not exceed two-and-four-tenths total spaces per unit unless all resident parking is provided underground per subsection (O)(2) of this section.

f. Surface parking areas are not permitted within the rear setback.

2. Bicycle Parking. Short-term bicycle parking (Class II bicycle parking facility) consists of racks that support the bicycle frame at two points and allow for the bicycle frame and one wheel to be locked to the rack with a U-lock.

Minimum bicycle parking requirements are:

a. Resident bicycle parking shall be provided at a minimum rate of one 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.

3. Vehicle Miles Traveled Analysis. Development proposals located in a high-VMT area shall include a VMT analysis that identifies travel demand management (TDM) measures and/or physical measures to reduce VMT impacts to less than significant. The VMT analysis should use the City/County Association of Governments of San Mateo County (C/CAG) VMT Estimation Tool.

N. Underground Basement Requirements. Requirements for underground basement design are:

1. Location. The perimeter of any underground basement shall not exceed the buildable area defined by the setbacks of the lot. Construction of the basement shall not cause the removal or disturbance of any heritage tree located in a setback.

2. Any habitable basement space shall only be exempted from floor area ratio requirements if one hundred percent of resident parking is located fully below grade.

3. 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 ten feet from the property line.

O. Underground Parking Incentives. Incentives to incorporate underground parking are as follows:

1. Habitable basement space shall not count towards floor area ratio; provided, that one hundred percent of resident parking is located fully below grade.

2. Below grade parking shall not count toward floor area ratio.

3. Up to three resident spaces per unit can be provided if all resident parking for the unit is located below grade. (Ord. 669 § 4, 2024)

17.36.010 Purpose.

This chapter establishes the allowed use provisions and development standards for uses located in the public facilities and schools district. It is the intent of this chapter to implement the land use categories outlined in the general plan by providing appropriate locations for public facilities and school uses. (Ord. 582 § 1 (Exh. A), 2009)

17.36.020 Characteristics of the District.

The public facilities and schools (PFS) district provides for the development of public uses (e.g., town hall, town corporation yard, public utilities, etc.) and schools (both public and private), consistent with the town’s general plan. Other appropriate uses may include churches, country clubs, and other assembly and civic uses upon issuance of a conditional use permit. It does not provide for the development of residential uses except for convent housing, teacher housing, student housing, and other residential uses when associated with primary nonresidential use of the same property with a conditional use permit. (Ord. 582 § 1 (Exh. A), 2009)

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

Land Use	Zoning District
Land Use	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	P⁵
Single-room occupancy	P⁵
Churches and places of worship	CUP
Convents	CUP
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

1Examples 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.

2Where 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.

3In addition to other conditions of approval, the planning commission shall require the following items where relevant:

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.

4Emergency 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.

5Shall only be permitted by right (i.e., as a staff-level decision and ministerial review, without discretionary review) on sites with a Multifamily Overlay District (RM-20/40) designation. Subject to compliance with objective design standards in section 17.36.070 (Multifamily Overlay District RM-20/40).

(Ord. 669 § 4, 2024; Ord. 667 § 4, 2025; Ord. 665 § 4, 2024; Ord. 591 § 7, 2010; Ord. 582 § 1 (Exh. A), 2009)

17.36.040 Development Standards.

Table 17.36.040 (Development Standards for PFS District) identifies the development standards for the PFS district, except the buildings, structures, or land used for governmental purposes by the United States of America, State of California, or Town of Atherton. All buildings and structures located in the PFS district shall be considered as main buildings and not as accessory structures.

Development Standard	Zoning District
Development Standard	PFS
Height, maximum	34 ft.
Lot coverage, aggregate, maximum	40% gross lot area
Front yard, minimum	60 ft.
Side yard, minimum, adjacent to residential	50 ft. when building height ≤ 22 ft. 75 ft. when building height > 22 ft.
Side yard, minimum, all others	See chapter 17.38.
Rear yard, minimum, adjacent to residential	60 ft. when building height ≤ 22 ft. 75 ft. when building height > 22 ft.
Rear yard, minimum, all others	60 ft.

1The setbacks for the PFS district properties in the vicinity of Ashfield Road and Station Way containing the town administration building, town hall, library, and other uses shall be as provided in section 17.33.040 (Development Standards) of the R-1B residential district.

2The side- and rear-yard setbacks for PFS district properties where a public or private school is located adjacent to a side or rear portion of another public or private school shall be a minimum of ten feet. The setback is limited to that portion of the property where a PFS district property is adjacent to another PFS district property.*

(Ord. 582 § 1 (Exh. A), 2009; Ord. 577 § 1)

*Code reviser’s note: Ordinance 582’s replacement of Title 17 inadvertently removed the setback provisions added by Ordinance 577. The provisions of Ordinance 577 have been inserted as Note 2, reflecting the intent of the city.

17.36.050 Guidelines for School Master Plans.

It is the city council’s policy to request the preparation of master plans for all private schools located in the PFS district. Where such master plans are prepared, they should be general enough to allow flexibility and adjustment of the facilities’ locations but shall have specific projections such as enrollment or floor space proposed. It is further requested that the schools involve interested neighbors, residents, town representatives, and others in the preparation of such master plans. Suggested content of master plans includes:

A. Land uses, their location, and extent;

B. Circulation patterns;

C. Locations for parking and parking standards;

D. Current enrollment projections and maximum enrollment anticipated;

E. A list of possible facilities to be developed;

F. A schedule or priority of development;

G. Identification of historic or other unique facilities, heritage trees, and their disposition;

H. Identification of uses and their days and hours of operation, including evenings; and

I. Identification of other institutions or uses at the facility.

Where master plans have been prepared and adopted by schools, it is requested that they be filed with the office of the town planner for public record. The town planner shall report annually to the planning commission at a regular meeting on the status of school master plans, their availability, and contents. Each private school in Atherton shall report to the planning commission meeting to provide input on the status of master plan preparation and implementation. In addition, the annual meeting shall be noticed to all property owners within five hundred feet of the boundaries of the schools. (Ord. 582 § 1 (Exh. A), 2009)

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. Beds and Population. The maximum number of client beds permitted in each emergency shelter shall be fifteen and the maximum client population permitted to be served nightly by the facility shall be fifteen. Any additional beds or population shall require a conditional use permit.

B. 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.

C. Handicap Accessibility. Each emergency shelter shall be completely handicap accessible.

D. Exterior Lighting. All exterior lighting shall be shielded or downlit so the source of light is not visible from other properties. (Ord. 669 § 4, 2024; Ord. 591 § 8, 2010)

17.36.070 Multifamily Overlay District (RM-20/40).

This section establishes development standards for multifamily uses on identified portions of lots that are zoned as public facilities and schools (PFS). The development standards establish objective criteria for the evaluation of multifamily housing so that it can be permitted by right on specific lots that are identified on the zoning map and in the Housing Element of the General Plan, or on additional lots as designated by the City Council.

The residential multifamily 20 overlay zone (RM-20) allows multifamily development of up to twenty units per acre on identified portions of lots that are zoned as public facilities and schools (PFS). Development within the RM-20 district shall have minimum of twelve units per acre.

The residential multifamily 40 overlay zone (RM-40) allows multifamily development of up to forty 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 units per acre. Where standards in this section conflict with Table 17.36.040, the standards in this section shall apply. 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.

A. Height. The maximum height for main buildings in the RM-20 overlay shall be thirty-four feet.

The maximum height for main buildings in the RM-40 overlay shall be forty-eight feet; provided, that the vertical midpoint between the eave and the top of roof does not exceed forty-two feet. If the main building has a flat roof, the maximum height is forty-two feet. See figure 17.36.070-1 (RM-40 Maximum Height).

Figure 17.36.070-1. RM-40 Maximum Height

a. Within the RM-20 overlay, any vertical end walls, sidewalls, or columns built facing the front setback line shall not exceed twenty-eight feet. Vertical end walls, sidewalls, and columns built at the side or rear setback line shall not exceed twenty-eight feet. See figure 17.36.070-2A (RM-20 Sidewall Height).

b. Within the RM-40 overlay, vertical end walls, sidewalls, and columns built at the setback line shall not exceed thirty-four feet. See figure 17.36.070-2B (RM-40 Sidewall Height).

c. Vertical end walls, sidewalls and columns built at the setback line shall not exceed twenty-one feet when facing an adjacent R-1 parcel. See figure 17.36.070-2C (R-1 Adjacent Sidewall Height).

d. End wall, sidewall and column heights can exceed these limits on side and rear conditions with an additional setback that is increased by a ratio of one foot for each one foot increase in height. See figures 17.36.070-2A (RM-20 Sidewall Height), 17.36.070-2B (RM-40 Sidewall Height), 17.36.070-2C (RM-20 R-1 Adjacent Sidewall Height), and 17.36.070-2D (RM-40 R-1 Adjacent Sidewall Height).

2. Height measurement: see section 17.42.030.

3. Dormers can exceed the vertical sidewall height and shall be in compliance with development standards in section 17.32.040(A)(4).

Figure 17.36.070-2A. RM-20 Sidewall Height

Figure 17.36.070-2B. RM-40 Sidewall Height

Figure 17.36.070-2C. RM-20 R-1 Adjacent Sidewall Height

Figure 17.36.070-2D. RM-40 R-1 Adjacent 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 feet.

a. The minimum setback from the property line is forty feet. See figure 17.36.070-3A (RM-20 Setbacks) and 17.36.070-3B (RM-40 Setbacks).

b. Within the RM-20 overlay, where the height of a main building placed at the setback is between twenty-eight and thirty-four feet, the setback shall be increased by a ratio of one foot for each one foot increase in height. See figure 17.36.070-3A (RM-20 Setbacks).

c. Within the RM-40 overlay, where the height of a main building placed at the setback is between thirty-four and forty-eight feet, the setback shall be increased by a ratio of one foot for each one foot increase in height. See figure 17.36.070-3B (RM-40 Setbacks).

a. The minimum setback from any property line that is adjacent to a parcel with an R-1 zoning designation shall be fifty feet. See figure 17.36.070-3C (R-1 Adjacent Setbacks).

b. Where the height of a main building placed at an R-1 adjacent setback is between twenty-one and forty-eight feet, the setback shall be increased by a ratio of one foot for each one foot increase in height. See figure 17.36.070-3C (R-1 Adjacent Setbacks).

Figure 17.36.070-3C. R-1 Adjacent Setbacks

C. Lot Coverage. The maximum lot coverage for buildings, including accessory buildings, shall be forty percent of the lot size. The maximum coverage for all impervious surfaces, not including buildings, shall be twenty percent. The maximum total coverage of all buildings and impervious surfaces shall be fifty percent.

Lot Coverage
Building	Impervious Surface	Lot
40%	20%	50%

D. Site Design. Requirements for design of the site are:

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-six feet.

e. Driveways shall conform to the requirements of the Fire Marshal.

a. All building entries shall be connected with resident parking areas by a pedestrian pathway that is at least five feet in width.

b. Pedestrian pathways are prohibited within ten 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.

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 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.

2. Plantings shall reach a minimum height of twelve feet within three 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 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 feet per building, as measured wall to wall. See figure 17.36.070-4A (Maximum Aggregate Façade Length).

Figure 17.36.070-4A. Maximum Aggregate Façade Length

2. For any building façade located at the required setback or within ten feet of a required setback, the maximum aggregate façade length shall be sixty-five feet. Any portion of the façade that causes the aggregate length to exceed sixty-five feet shall be set back a minimum of ten feet from the front setback line. See figure 17.36.070-4B (Maximum Aggregate Façade on Setback).

Figure 17.36.070-4B. 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 primary entries.

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 primary entries shall be allowed.

In addition to the standards in subsection (G)(1) of this section, a primary entry shall include one or more of the three frontage typologies listed in standards in subsections (G)(2) through (G)(4) of this section:

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 17.36.070-5 (Common Entry).

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 feet. A common entry shall provide access to all units within a main building.

3. Stoop. A stoop is a small, raised entry that shall conform with the following standards. See figure 17.36.070-6 (Stoop).

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 inches. A stoop shall provide direct access to no more than two units.

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 17.36.070-7 (Frontage Court).

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 units. The height of sidewalls facing the courtyard shall not exceed a 2:1 ratio to its depth or width.

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 17.36.070-8 (Terrace).

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 feet apart. A terrace shall provide direct access to no more than four units.

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 feet of the setback from the R-1 parcel. Roof decks shall not be permitted. See figure 17.36.070-9 (Balcony Placement).

7. Minimum Window Detail requirements are:

a. Windows shall be recessed at least two inches from the exterior wall plane to the window glass. See figure 17.36.070-10 (Window Detail Requirements).

b. Windowsills shall project a minimum of two inches from the surrounding exterior wall plane. See figure 17.36.070-10 (Window Detail Requirements).

c. All windowsills for nonsleeping rooms facing an R-1 district, located on the second floor or higher, shall be elevated a minimum of fifty-four inches above the floor plate. See figure 17.36.070-11 (Sill Height).

e. Windows shall be vertically oriented and taller than they are wide.

f. 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 feet on the main building.

2. Roof parapets, when included, shall be a minimum of three feet tall and may not exceed the maximum building height. Roof parapets shall be consistent in material and color with the main building.

3. Any equipment placed on the rooftop of a building shall be screened entirely.

J. Site Lighting. Minimum Site Lighting requirements are:

1. No exterior lighting element shall be placed above the height of eight 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 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 Structures. Where standards in this section conflict with chapter 17.40, the most restrictive standard shall apply.

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 feet, or a minimum of fifteen feet on a property line that is adjacent to an R-1 parcel.

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.

d. Trash and recycling enclosures shall have a gate and a roof.

e. Trash and recycling enclosures are not permitted within any setback.

a. Projects with six 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.

L. Parking. Minimum Parking requirements are:

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 spaces per unit.

c. Total resident and guest parking can be increased to a maximum of two spaces per unit if all the resident and guest parking spaces are provided in a below-grade parking garage.

a. No more than twenty-five 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 feet. Livable space shall include any multifamily housing use that does not include vehicle parking.

c. Partially sub-grade parking shall not have an exposed façade that exceeds five feet above grade and shall provide landscape screening with a minimum depth of ten feet along the entire façade length.

3. Bicycle Parking. Short-term bicycle parking (Class II bicycle parking facility) consists of racks that support the bicycle frame at two points and allow for the bicycle frame and one wheel to be locked to the rack with a U-lock.

Minimum bicycle parking requirements are:

a. Resident bicycle parking shall be provided at a minimum rate of one 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.

4. Vehicle Miles Traveled Analysis. Development proposals located in a high-VMT area shall include a VMT analysis that identifies travel demand management (TDM) measures and/or physical measures to reduce VMT impacts to less than significant. The VMT analysis should use the City/County Association of Governments of San Mateo County (C/CAG) VMT Estimation Tool. (Ord. 669 § 4, 2024)

17.37.010 Purpose and Relationship to Base Zoning District.

This chapter establishes the Parker Avenue overlay district. This district is intended to be combined with the Residential District R-1A and is designed to provide development standards that are adapted to the unique circumstances of a large cluster of small lots. In any conflict between the standards of the R-1A Base District and this overlay district, the overlay district regulations shall apply. (Ord. 587 § 1, 2010)

17.37.020 Characteristics of the District.

The Parker Avenue Overlay District (P) provides for the development of single-family residential uses on lots located in the R-1A District which are significantly less than one acre in area and which front on a seventy-foot-wide public right-of-way. This right-of-way is significantly wider than the Town’s standard local street. The Parker Avenue overlay district allows for more total floor area and more second story floor area than the base R-1A district. Unchanged R-1A rear setbacks and reduction in permitted heights for new development are intended to minimize any adverse impacts on the privacy or views of neighboring homes. (Ord. 587 § 1, 2010)

17.37.040 Development Standards Modifications.

A. Height. The standard maximum building height for main buildings shall be twenty-eight feet; provided, that vertical sidewalls and columns may not exceed twenty feet. End walls shall be perpendicular to lot depth.

B. Maximum Floor Area Ratio. The maximum floor area ratio shall be determined by the following equation:

Floor area in square feet = (lot size in square feet × .165) + 1,500 square feet

The floor area above the first floor of the main building for all lots shall not exceed one thousand one hundred thirty-two square feet.

C. Setback. For single story portion of the main building that does not exceed fifteen feet in height, the front yard setback shall be twenty-three feet three inches. (Ord. 587 § 1, 2010)

17.38.010 Minimum Side Yards.

Minimum side yards shall be required on each side of a lot as specified in Table 17.38.010-1 (Minimum Side Yard Requirements).

Lot Width		Minimum Side Yard
From	To, But Not Including	Minimum Side Yard
200' or over		50'
197' 0"	200' 0"	49' 6"
194' 0"	197' 0"	49' 0"
191' 6"	194' 0"	48' 6"
189' 0"	191' 6"	48' 0"
186' 6"	189' 0"	47' 6"
184' 0"	186' 6"	47' 0"
181' 6"	184' 0"	46' 6"
179' 0"	181' 6"	46' 0"
176' 6"	179' 0"	45' 6"
174' 0"	176' 6"	45' 0"
171' 6"	174' 0"	44' 6"
169' 0"	171' 6"	44' 0"
166' 6"	169' 0"	43' 6"
164' 0"	166' 6"	43' 0"
161' 6"	164' 0"	42' 6"
159' 0"	161' 6"	42' 0"
156' 6"	159' 0"	41' 6"
154' 0"	156' 6"	41' 0"
151' 6"	154' 0"	40' 6"
149' 0"	151' 6"	40' 0"
146' 6"	149' 0"	39' 6"
144' 0"	146' 6"	39' 0"
141' 6"	144' 0"	38' 6"
139' 0"	141' 6"	38' 0"
136' 6"	139' 0"	37' 6"
134' 0"	136' 6"	37' 0"
131' 6"	134' 0"	36' 6"
129' 0"	131' 6"	36' 0"
126' 6"	129' 0"	35' 6"
124' 0"	126' 6"	35' 0"
121' 6"	124' 0"	34' 6"
119' 0"	121' 6"	34' 0"
116' 6"	119' 0"	33' 6"
114' 0"	116' 6"	33' 0"
111' 6"	114' 0"	32' 6"
109' 0"	111' 6"	32' 0"
106' 6"	109' 0"	31' 6"
104' 0"	106' 6"	31' 0"
101' 6"	104' 0"	30' 6"
99' 6"	101' 6"	30' 0"
96' 6"	99' 6"	29' 0"
94' 0"	96' 6"	28' 0"
91' 6"	94' 0"	27' 0"
89' 0"	91' 6"	26' 0"
86' 6"	89' 0"	25' 0"
84' 0"	86' 6"	24' 0"
81' 6"	84' 0"	23' 0"
79' 0"	81' 6"	22' 0"
76' 6"	79' 0"	21' 0"
74' 0"	76' 6"	20' 0"
71' 6"	74' 0"	19' 0"
69' 0"	71' 6"	18' 0"
66' 6"	69' 0"	17' 0"
64' 0"	66' 6"	16' 0"
61' 6"	64' 0"	15' 0"
59' 0"	61' 6"	14' 0"
56' 6"	59' 0"	13' 0"
54' 0"	56' 6"	12' 0"
51' 6"	54' 0"	11' 0"
20' or under	51' 6"	10' 0"

(Ord. 582 § 1 (Exh. A), 2009)

Atherton City Zoning Code

Division II

Districts and Development Standards

17.30.010 Designation of Districts.

For the purposes of this title, the town is divided into the following classes of districts as shown on the maps hereinafter included by reference:

A. Residential district R-1A.

B. Residential district R-1B.

C. Parks and open space district (POS District).

D. Public facilities and school district (PFS District). (Ord. 582 § 1 (Exh. A), 2009)

17.30.020 Zoning Plan.

17.30.030 Allowed Uses Generally.

17.30.040 Similar Use Determination.

A. The proposed use will be consistent with the general plan.

B. The proposed use will be consistent with the purposes of the applicable zoning district.

17.30.050 Certain Commercial-Residential Uses Prohibited.

17.30.060 Interpretation of District Boundaries.

A. When a boundary line is indicated as following a street or similar right-of-way, it shall be interpreted as following the centerline of that right-of-way.

B. Where a boundary line is indicated as approximately following a lot line, the boundary line shall be interpreted to follow that lot line.

C. Where a boundary line divides a lot or crosses unsubdivided property, the location of such boundary shall be interpreted as being the closest lot line. (Ord. 582 § 1 (Exh. A), 2009)

17.30.070 Legal Lots.

17.30.080 Zoning Overlay Districts.

A. Parker Avenue Overlay Districts (P);

B. Multifamily Overlay District (RM-10);

C. Multifamily Overlay District (RM-20/40). (Ord. 669 § 4, 2024)

17.32.010 Purpose.

17.32.020 Characteristics of the District.

17.32.030 Allowed Uses and Permit Requirements.

P	=	Land use permitted by right
CUP	=	Land use permitted with approval of a conditional use permit

Land Use	Zoning District
Land Use	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 unit²	P
Single-room occupancy	P
Churches and places of worship	CUP
Public utilities or facilities	CUP