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Piedmont, California: ADU Regulations

Date Updated:



Zone A, Zone B, Zone C, Zone D, Zone E

Types of ADUs allowed:

Detached, attached and junior ADUs are allowed.



Lot size:

No specific min/max, however, 17.20.040 dictates any single-family lot be at least 8,000 sq.ft.

ADU size:

Attached ADU: Floor area may not exceed 50% of the existing living area up to a maximum of 850 sq.ft. (one bedroom) or 1,000 sq.ft. (more than 1 bedroom)
Detached ADU: up to a maximum of 850 sq.ft. (one bedroom) or 1,000 sq.ft. (more than 1 bedroom)
Note: Units may be expanded to 1,200 sq.ft. if made affordable to low income (less than 50% area median income for Alameda County)

Lot coverage:

ADU up to 800 sq.ft. has no maximum lot coverage.
ADU over 800 sq.ft match underlying district






ADUs must include independent and permanent provisions for eating and cooking.
JADU shall include an efficiency kitchen that provides a cooking facility, appliances, cabinets, and food preparation counter in proportion to the size of the JADU, and subject to Building Code requirements.


ADUs must include independent and permanent provisions for bathing and sanitation.
JADU may share sanitation facilities with the existing, proposed or approved structure or have separate sanitation facilities. The sanitation facilities must be located in the same building as the JADU.


No parking shall be required. When a garage, carport, or covered parking structure is demolished in conjunction with the construction of an accessory dwelling unit or converted to an accessory dwelling unit, the City shall not require the replacement of off street parking spaces.


If an accessory dwelling unit is not converted from an existing structure, the minimum setback is 4' from the side and rear lot line. No setback is required to construct an accessory dwelling unit within an existing structure that is converted to an accessory dwelling unit or a new structure constructed in the same location and the same dimension as an existing structure. 

JADU: If an expansion of up to 150 square feet is proposed in order to meet ingress or egress; the rear and side yard setbacks are 4 feet measured from the property line. Front setback according to zone.



Rear Yard Coverage:

N/A, however an accessory dwelling unit 800 sq.ft. in floor area or less, shall have no minimum landscape area. Minimum landscape area for an accessory dwelling unit greater than 800 sq.ft. in floor area shall be that of the underlying zoning district.


The design of the structure(s) housing the proposed accessory dwelling unit must meet applicable design criteria in the Piedmont Design Guidelines and any additional design guidelines applicable to accessory dwelling units approved by City Council resolution.

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


Independent, exterior access is required for any ADU.

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!