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Los Altos, California: ADU Regulations

City or County:

Los Altos, California

Date Updated:




Types of ADUs:

Attached, Detached and Junior



Lot Size:

No minimum

Maximum ADU Floor Area:

Attached: 850 sq.ft. (1 bedroom), 1,200 sq.ft (more than 1 bedroom) and not more than 50% of living area (though a 850 sq.ft. unit must be permitted)

Detached: 850 sq.ft. (1 bedroom), 1,200 sq.ft (more than 1 bedroom).

Junior: 500 sq.ft.

Lot Coverage:







Require separate kitchen facilities with food preparation counter and a storage counter of reasonable size in relation to the ADU.
Attached/Detached: Must include at least a sink, a refrigerator of no less than 10 cubic feet, and either a cooktop and an oven, or a range.
Junior: Efficiency kitchen, as per state law. Cooking appliances can includes a hot plate, or counter-top cooking. A wall installed oven is not required.


At least one separate bathroom facility is required.

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


ADU must have one parking space per unit or per bedroom, whichever is less. No parking standards shall be imposed on an ADU that is: (a) located within one-half mile of a public transit stop or station, (b) located within an architecturally and historically significant historic district, (c) is part of the proposed or existing primary dwelling or an existing accessory structure, (d) not offered on-street parking permits, (e) within one block of a car share vehicle.

No parking required for JADU.


Side and Rear: 4’ (though applicants are encouraged to comply voluntary with setbacks of 10’ to reduce privacy impacts. ADU of 10’ setback is removed from daylight plane restrictions).

Detached must be 5’ from Primary Residence (unless it would prohibit constructing 850 sq.ft. ADU, then this is waived).

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


Attached/Detached: must comply with standards of underlying zoning district.


ADU cannot face the street.

Rear Yard Coverage:

Must comply with coverage standards of the underlying zoning district.


ADU must relate to the primary dwelling by use of similar exterior wall materials, window types, trims, roofing material and roof pitch. A minimum sill height of 5’ on the second story within 15’ of the property line that face out to the neighbors to mitigate privacy concers.

Landscaping of ADU must meet the standards of the underlying zoning district.

Daylight plane requirements are as follows:
- Daylight plane starts at 8’ at property line and proceeds inward at 6:12 slope. At 10’ from property line, structure can increase to 16’
- Daylight plane not enforced for structures that abut a city street or alleyway in the rear of the parcel

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


Must be separate from existing primary dwelling.

Code Source:

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!