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Palo Alto, California: ADU Regulations

City or County:

Palo Alto, California

Date Updated:



Any zone in which single-family or multifamily residential is a permitted land use

Types of ADUs:

Attached, Detached, Garage Conversion and Junior ADU


Attached: 2-story in RE and OS district, single-story in other districts

Detached: single-story

Conversion/JADU: N/A

Lot Size:

Not included in emergency ordinance.

Maximum ADU Floor Area:

Attached: 850 sq.ft. (one bathroom/studio), or 1,000 sq.ft. (more than one bedroom), and shall not exceed 50% of the proposed or existing living area of the primary dwelling unit. The minimum unit size shall be 150 square feet.

Detached ADU: 900 sq.ft. (one bathroom/studio), or 1,000 sq.ft. (more than one bedroom),.

Junior ADU: 500 sq.ft.

Lot Coverage:

ADUs are included in the lot coverage and FAR requirements applicable to each parcel. Up to 800 sq.ft. of ADU space is exempt.

When the development of an ADU on a parcel with an existing single-family residence would result in the parcel exceeding the lot coverage requirement, the ADU shall not be included in the calculation of lot coverage applicable to the property, so long as the parcel meets the underlying zoning district’s minimum lot size requirement or is substandard by no more than 10% of the minimum lot size requirement.


No min/max


No min/max


All* ADUs require separate kitchen facilities.

Junior: A cooking facility with appliances, and a food preparation counter and storage cabinets that are of reasonable size in relation to the size of the junior accessory dwelling unit.


All* ADUs require separate bathroom facilities.

*Junior ADUs may include separate bathroom or share bathroom with existing structure.

Note: Drainage and sewer connections should be assessed on a project by project basis.


None required, however, any required parking displaced by ADU must be restored on-site. Additionally, in RE districts, if covered parking offered to ADU, cannot be larger than 200 sq.ft.

Optional parking for accessory dwelling units may be provided by means of uncovered or tandem spaces on existing driveways within the required front and street side yards; covered parking and mechanical automobile parking lifts may be located in required side and rear yard setbacks in compliance with Section 18.40.050. All new parking spaces and structures shall comply with development standards of the underlying zoning and the applicable parking design standards in Chapter 18.54, except as provided below:
i. 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.
ii 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.


Detached: 4' from interior side/rear property line

Conversions: None except as required for fire safety

Junior ADUs: None

Note: Except as otherwise provided in this section, ADUs shall comply with the underlying zoning district’s setbacks, including daylight plane requirements, except to the extent daylight plane requirements would preclude an accessory dwelling unit from reaching a height of 16’.


Attached: 1-story/17', 2-story/30' in RE District, 2-story/25' in OS District

Detached: 16'

Conversions/Junior: n/a


No projections, such as but not limited to windows, doors, mechanical equipment, venting or exhaust systems, shall be permitted to encroach into the required setbacks and daylight plane, with the exception of a roof eave up to 2’.

Detached: No basement shall encroach into a required rear yard setback. No portion of a building may encroach into a daylight plane beginning at a height of 8’ at the property line and increasing at a slope of 1’ for every one foot of distance from the property line, except that the beginning height shall be increased to the extent necessary to allow an accessory dwelling unit to reach a height of 16’.

Rear Yard Coverage:



No design review necessary.

Note: Historic Neighborhoods or Districts should be assessed on a project by project basis.


Require independent exterior access from main residence.

Attached entrances, except for corner lots, must face different property line than main residence or be located on rear half of lot.

Second story doors and decks shall not face a neighboring dwelling unit and second story windows shall be placed above eye-level or utilize obscured glazing. Where feasible, screening features, including landscaping, shall be installed between an two-story ADU and a neighboring dwelling.

Source Code:

Important Note: Rules and regulations are updated and changed frequently. It’s one of our jobs to be up to speed and navigate those regulations. Let us know if our website isn’t up to date or if you have any information that could help. Cheers!