Danville's ADU code has been amended to comply with recent state regulations. The most recent specifications for approving an ADU in Danville are listed below.
Any single-family residential district.
NUMBER OF UNITS ALLOWED
Maximum of two (2): One (1) attached or detached ADU plus one (1) JADU.
- JADU: Maximum 500 square feet
- ADUs in districts zoned with a maximum lot size less than 40,000 square feet: 1,200 square feet. Attached ADUs shall not exceed 50% of primary residence.
- ADUs in districts zoned with a maximum lot size more than 40,000 square feet: 2,000 square feet. Attached ADUs shall not exceed 50% of primary residence.
- Garages attached to a detached ADU do not count towards ADU square footage and can be a maximum of 20’ x 22’ or 440 square feet.
*A minimum of 850 square feet for one-bedroom units, or 1,000 square feet for units with more than one bedroom, shall be allowed for attached ADUs, regardless of the size of the primary residence.
*There are no size minimum requirements.
Detached Max Height
16 feet, 24 feet if the ADU meets the same setbacks applicable to the primary residence.
*Height is measured from finished grade.
Attached Max Height
16 feet or the same height allowed for the primary residence if the unit meets the setbacks applicable to the primary residence.
*Height is measured from finished grade
Minimum Lot Size
Both attached and detached ADUs
- Front: Same as required under the applicable zoning district
- Side: 4 feet
- Rear: 4 feet
*Setbacks are measured to the furthest projecting feature. This includes, but is not limited to, eaves and gutters.
*If an ADU is constructed in the same location (and same dimensions) as an existing non-conforming structure (example: detached garage), it does not have to comply with the rear and side yard setbacks.
One additional space is required unless:
- The ADU is located within one-half mile walking distance of public transit.
- The ADU is located within an architecturally and historically significant historic district.
- The ADU is part of the proposed or existing primary residence or an accessory structure.
- When on-street parking permits are required, but not offered to the occupant of the Accessory Dwelling Unit.
- When there is a car share vehicle located within one block of the ADU.
- A garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU or converted to an ADU.
- Conditioned space other than a garage is converted into a JADU.
* Please refer to our ADU Parking Map for more clarification
- ADU: No owner-occupancy requirement for any of the units on the property.
- JADU: The property owner must occupy either the remaining portion of the structure or the newly created JADU, unless the owner is another governmental agency, land trust, or housing organization. A deed notification must be recorded specifying this requirement.
(3) (A) A local agency, special district, or water corporation shall not impose any impact fee upon the development of an accessory dwelling unit less than 750 square feet. Any impact fees charged for an accessory dwelling unit of 750 square feet or more shall be charged proportionately in relation to the square footage of the primary dwelling unit.
Source: AB-68 Land Use: Accessory Dwelling Units (https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=201920200AB68)
- Floor Area Ratio (FAR): None required. Any ADU ≤ 800 square feet is allowed, if it meets all development standards applicable to its zoning district.
- Fire Sprinklers: Required for the ADU if it is required for the main home. Note: California Building Code requires 1-hour construction or fire sprinklers for ADUs that are located ≤ 5 feet from another structure.
- Solar power is required for detached ADUs.
- The municipality shall provide a ministerial review process that is not based on discretionary approval for an ADU. The process shall take no less than 120 days. Valid applications submitted for ADUs, if not approved or denied within 120 days from submission, shall be considered approved. ~ State Standards
- New or separate utility connections may be required, but connection fees or capacity charges shall be proportional to the impact of the ADU on the sewer or water systems. It shall not be disproportionately higher than those to develop primary dwellings, so as not to deter the development of ADUs.
510 La Gonda Way
Danville, CA 94526
Civil Engineering Associate
This quick reference manual should be useful to you while you work on your ADU project. Our in-house permit technician will process your permit on your behalf without adding any markups as part of our service if you choose to construct with us.
Please don't hesitate to schedule a meeting with us if you're interested in building with ADU.Works or to give us a call at (650)-227-4810. We are happy to answer any questions you may have and go over the details of how your permission will be processed. Our staff is eager to hear from you.