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Palo Alto, California: ADU Regulations

City or County:

Palo Alto, California

Date Updated:



Attached/Detached: R1/R2/RE/RMD/OS (RM 15/30/40 when the property is used for a single-family dwelling)

Conversion: R1/RE (conversions in other districts subject to attached/detached ADU standards)

Junior ADU: R1/RE/RMD/OS (RM 15/30/40 when property used for a single-family dwelling)

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:

R-1/RE/R-2/RMD/PC: 5,000 sq.ft. (10 acres in OS)

(no minimum lot sizes for Conversions or Junior ADUs)

Maximum ADU Floor Area:

Attached: lesser of 600 sq.ft., or 50% of existing living area

Detached: 900 sq.ft.

Conversion: none (must be located within existing residence)

Junior: 500 sq.ft. (must include conversion of existing bedroom)

Lot Coverage:

ADUs are included in the lot coverage and FAR requirements applicable to each parcel.

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 ADUs must at least have efficiency kitchen with following: sink w/maximum 1.5-inch waste line diameter; cooking facility with appliances not requiring more than 120v, natural, or propane gas; food preparation counter and storage cabinets.


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.


Attached: same as main residence (5' min. from side/rear property lines when located above garage in RE/OS)

Detached: 6' from interior side/rear property line, 16' from street side yard (not permitted in front yard setback)

Conversions: None except as required for fire safety

Junior ADUs: None

Note: Fire Department regulations should be assessed on a project by project basis.


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

Detached: 17'

Conversions/Junior: n/a


Detached cannot be located in front yard setback. Conversion and Junior must be located within existing residence or structure. Any windows, doors, exhaust systems, or mechanical equipment must be at least 6' from the property line.

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.

Any window, door or deck of a second story ADU shall utilize techniques to lessen views onto adjacent properties.

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!