(a) This section shall govern applications for ADUs and JADUs that do not qualify for approval under Section 18.09.030 and for which the city may impose local standards pursuant to Government Code section 65852.2, subdivisions (a) through (d). Nothing in this section shall be interpreted to prohibit an ADU of up to 800 square feet, at the heights stated in Table 2, with a four foot side and rear setbacks.
(b) The Development Standards for units governed by this section are provided in Table 2. These regulations do not limit the height of existing structures converted into ADU/JADUs unless the envelope of the building is proposed to be modified beyond any existing legal, non-conforming condition.
Table 2: All other Units
Attached | Detached | JADU |
Attached | Detached | JADU | |
Number of Units Allowed1 | 1 | 1 | |
Minimum size | 150 sf | ||
Maximum size | 900 sf (1,000 sf for two or more bedrooms); no more than 50% of the size of the single-family home | 900 sf (1,000 sf for two or more bedrooms) | 500 sf |
Setbacks | 4 feet from side and rear lot lines; underlying zone standard for front setback | ||
Daylight Plane | Underlying zone standard per footnote (7) | N/A | Underlying zone standard |
Maximum Height3 | Underlying zone | ||
Res. Estate (RE) Open Space (OS) All other eligible zones | 30 feet 25 feet 16 feet(5), (6), (7) | ||
Parking | None | ||
Square Footage Exemption when in conjunction with a single family home(4) | Up to 800 sf | Up to 500 sf(4) | |
(1) An attached or detached ADU may be built in conjunction with a JADU on a lot with an existing or proposed single-family home. One attached or detached ADU may be built in conjunction with an existing or proposed multi-family building.
(2) Lofts where the height from the floor level to the underside of the rafter or finished roof surface is 5' or greater shall count towards the unit's floor area.
(3) Units built in a flood zone are not entitled to any height extensions granted to the primary dwelling.
(4) Lots with both an ADU and a JADU may exempt a maximum combined total of 800 square feet of the ADU and JADU from FAR, Lot Coverage, and Maximum House Size calculations. Any square footage that exceeds this exemption shall contribute to the FAR, Lot Coverage, and (if attached) Maximum House Size calculations for the subject property. This exemption is not afforded to lots with existing or proposed multifamily dwellings.
(5) A height of 18 feet for a detached ADU on a lot with an existing or proposed single-family or multi-family dwelling unit that is within one-half of one mile walking distance of a major transit stop or a high-quality transit corridor, as those terms are defined in Section 21155 of the Public Resources Code. An additional two feet in height shall be provided to accommodate a roof pitch on an ADU that is aligned with the roof pitch of the primary dwelling unit.
(6) A height of 18 feet for a detached ADU on a lot with an existing or proposed multi-family, multistory dwelling.
(7) A height of 25 feet or the height limitation in the underlying zone district that applies to the primary dwelling, whichever is lower, for an ADU that is attached to a primary dwelling. These ADUs shall not exceed two stories in height.
(c) A single-family dwelling shall exist on the lot or shall be constructed on the lot in conjunction with the construction of an ADU/JADU.
(d) ADU and/or JADU square footage shall not be included in FAR, lot coverage, and maximum house size calculations for a lot with an existing or proposed single family home, up to the amounts stated in Table 2. ADU and/or JADU square footage in excess of the exemptions provided in Table 2 shall be included in FAR, lot coverage, and maximum house size calculations for the lot.
(e) When there is an ADU or JADU attached to an existing or proposed primary dwelling, the shared wall between these units shall contribute to the maximum allowable Floor Area, Lot Coverage, and Maximum House Size of the primary unit. For a single-family home, this measurement shall be taken to the outside stud wall in accordance with Section 18.04.030(a)(65)(D). For a multi-family dwelling, this measurement shall be taken to the outside surface of exterior walls in accordance with Section 18.04.030(a)(65)(B) and (C).
(f) Attached units shall have independent exterior access from a proposed or existing single-family dwelling. Except for JADUs, attached units shall not have an interior access point to the primary dwelling (e.g. hotel door or other similar feature/appurtenance).
(g) No protected tree shall be removed for the purpose of establishing an accessory dwelling unit except in accordance with Chapter 8.10. Notwithstanding any contrary provision of Chapter 8.10, to the extent the City’s application checklist requires a tree disclosure statement, it may be completed by the property owner.
(h) For properties listed in the Palo Alto Historic Inventory, the California Register of Historical Resources, the National Register of Historic Places, or considered a historic resource after completion of a historic resource evaluation, compliance with the appropriate Secretary of Interior's Standards for the Treatment of Historic Properties shall be required.
(i) Noise-producing equipment such as air conditioners, water heaters, and similar service equipment that exclusively serves an ADU/JADU may be located anywhere on the site, provided they maintain the underlying front yard setback requirements of the property and, if the property is a corner lot, a 10-foot street-side setback. All such equipment shall be insulated and housed, except that the Director may permit installation without housing and insulation, provided that a combination of technical noise specifications, location of equipment, and/or other screening or buffering will assure compliance with the city's Noise Ordinance at the nearest property line. All service equipment must meet the city's Noise Ordinance in Chapter 9.10 of the Municipal Code.
(j) Setbacks
1. Detached units shall maintain a minimum three-foot distance from the primary unit, measured from the exterior walls of structures.
2. A basement or other subterranean portion that serves an ADU/JADU may encroach into a setback required for the primary dwelling provided the following conditions are met:
(A) Newly constructed basement walls are no closer than four feet to an adjacent interior side or rear property line.
(B) A new lightwell associated with a basement shall not be placed closer than four feet to an adjacent interior property line. When visible from the right of way, these facilities shall be screened from view with vegetation.
(C) The new basement shall not negatively impact tree roots on the subject property or on adjacent lots such that it would require a protected tree to be removed or cause the protected tree to die.
(D) Habitable ADU/JADU basements shall contribute toward the unit’s total allowable floor area. Any floor area in excess of the exemptions provided in this Section shall contribute to the total allowable limits for the site.
3. Projections, including but not limited to windows, doors, mechanical equipment, venting or exhaust systems, are not permitted to encroach into the required setbacks, with the exception of a roof eave of up to two feet.
4. For corner lots developed as a single-family home only, when an existing or proposed primary dwelling unit is expanded or constructed simultaneously with the construction of a new ADU/JADU, all structures may be built to a 10-foot street-side setback and a 16-foot front yard setback, regardless of the presence of a special setback, unless a fire or life-safety regulation requires a greater setback.
5. When an existing, legal, nonconforming structure is converted or reconstructed to create an ADU/JADU, any portion of the ADU/JADU that is in the same location and falls within the building envelope of the original structure shall not be subject to the development standards stated in this Section. Any portion of the ADU/JADU that is in a different location or exceeds the envelope of the original structure shall comply with the development standards stated in this Section.
6. Notwithstanding the development standards stated in Table 2 and paragraph (5) above, when an existing, legal, non-conforming structure is converted in place to an ADU/JADU, the envelope of the structure may be modified to encroach further into a setback or daylight plane as follows:
(A) The height of the existing structure may be increased by no more than one linear foot in height commensurate to the existing roofline of the structure provided the height of the addition does not exceed 12 feet from grade. The roofline shall not be changed to a style other than what currently exists on the structure.
(B) Each non-conforming wall may be expanded by no more than six inches in thickness based on its existing location and configuration, as measured to exterior surface of the material, to provide for greater insulation and energy requirements provided that a minimum of one foot is maintained between the addition and an adjacent interior property line. An existing wall of a structure that does not currently have a separation of one foot from a parallel property line shall not be expanded outward.
(C) All other additions not specified here shall follow the standard setbacks for the ADU/JADU identified in Table 2.
(k) Design
1. Except on corner lots, where feasible, the unit shall not have an entranceway facing the same lot line (property line) as the entranceway to the main dwelling unit unless the entranceway to the accessory unit is located in the rear half of the lot. Exterior staircases to second floor units shall be located toward the interior side or rear yard of the property.
2. Privacy
A. Second story doors and decks shall not face a neighboring property line. Second story decks and balconies shall utilize screening barriers to prevent views towards an adjacent interior property line. These barriers shall be a minimum five-foot, six-inch height, from the floor level of the deck or balcony and shall not include perforations of any kind that would allow visibility between properties.
B. Windows on a second floor, loft, or equivalent elevated space, excluding those required for egress, shall have a five-foot sill height as measured from the second-finished floor level, or utilize opaque glazing on the entirety of any window that faces an adjacent interior property line.
C. Windows on a second finished floor, loft, or equivalent elevated space, shall be offset from neighbor's windows to maximize privacy.
D. Where feasible, egress windows on the first and second finished floor of an ADU or JADU shall not face towards an adjacent interior property line. If this is not feasible, then these windows shall utilize opaque glazing on the whole window.
E. If the first finished floor of an ADU or JADU is two feet or more above grade, then first floor windows shall include the following:
i. Non-egress, operable windows facing an adjacent interior property line shall have a windowsill(s) that start five feet above the first finished floor for the unit;
ii. Non-egress, non-operable windows facing an adjacent interior property line shall have the lower half of window(s) (minimum of five feet above the first finished floor) utilize opaque glazing.
F. Where feasible, the use of skylights (whether operable or not) shall be used in lieu of operable windows that face adjacent interior properties.
G. No exterior lighting shall be mounted above seven feet. All lighting mounted on walls shall be directed downwards and shall not direct light towards adjacent interior property lines. Any ground lighting shall not direct light upwards to the building or sky.
(l) Parking
1. Replacement parking is not required when a garage, carport, or covered parking structure is converted to, or demolished in conjunction with the construction of, an ADU.
2. Replacement parking is required when an existing attached garage, carport, or covered parking structure is converted to a JADU or when a required, existing, uncovered parking space is expanded into an ADU/JADU. These replacement spaces may be provided as uncovered spaces in any configuration on the lot including within the front or street side yard setback for the property.
A. The Director shall have the authority to modify required replacement parking spaces by up to one foot in width and length upon finding that the reduction is necessary to accommodate parking in a location otherwise allowed under this code and is not detrimental to public health, safety or the general welfare.
B. Existing front and street side yard driveways may be enlarged to the minimum extent necessary to comply with the replacement parking requirement above. Existing curb cuts shall not be altered except when necessary to promote public health, safety or the general welfare.
3. When parking is provided, the unit shall have street access from a driveway in common with the main residence in order to prevent new curb cuts, excessive paving, and elimination of street trees, unless separate driveway access will result in fewer environmental impacts such as paving, grading or tree removal.
4. When a single-family dwelling unit is permitted simultaneously with the construction of new ADU/JADUs, the primary unit’s covered parking requirements identified in Chapter 18.10 and 18.12 do not need to be provided. Two uncovered parking spaces shall be provided in any configuration on the lot including within the front or street-side setback for the property.
5. If covered parking for a unit is provided in any district, the maximum size of the covered parking area for the accessory dwelling unit is 220 square feet. This space shall count towards the total floor area for the site but does not contribute to the maximum size of the unit. Any attached garage shall not have an interior access point to the ADU/JADU (e.g. hotel door or other similar feature/appurtenance).
(m) Miscellaneous requirements
1. Street addresses shall be assigned to all units prior to building permit final to assist in emergency response.
2. The unit shall not be sold separately from the primary residence.
3. Rental of any unit created pursuant to this section shall be for a term of 30 days or more.
4. The installation of fire sprinklers shall not be required in an accessory dwelling unit if sprinklers are not required for the primary residence. Nothing in this section shall preclude the Fire Marshal from accepting fire sprinklers as an alternative means of compliance with generally applicable fire protection requirements.
(Ord. 5585 § 2 (part), 2023: Ord. 5574 § 2 (part), 2023: Ord. 5557 § 6, 2022: Ord. 5507 § 3 (part), 2020)