Palo Alto, CA

Accessory Dwelling Unit (ADU) City Regulations


Attached/Detached: R1/R2/RE/RMD/OS (RM 15/30/40 when 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)

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)

Number of Bedrooms:

No minimum/maximum.


No minimum/maximum.


All* require separate bathroom and kitchen facilities.

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


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


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

Detached: 1-story/17'

Conversions/Junior: none


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 property line.

Rear Yard Coverage:



No design review necessary.


Requires 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.  

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