ADU Jurisdiction Guide: City of Danville
Fees and Regulations (July 2022)
All Residential Zoning Area (Single-Family/Multi-Family)
ADU Size Limitations
- 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.
ADU Building Height
- 16 Feet (Attached)
- 24 Feet (Detached)
Minimum Lot Size
ADU Construction Limits
- For existing lots with a single-family residence, or lots in single-family zoning districts, one attached unit (ADU or JADU) and one detached unit (ADU) is allowed.
- For existing lots with multi-family dwellings, ADU’s may be added; however, no more than a 25% increase in units is allowed, and no more than two ADUs may be detached (for example, a lot with 4 existing units may only add one ADU on site).
- 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.
Parking Space Requirements
- 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.
Owner Occupancy Requirements
None. Owner occupancy of one dwelling on-site is required for JADUs only.
- 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.
- 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.
(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.
ADU Permit Process
Step 1: Come talk to the Town first. Decisions such as pursuing an attached or detached ADU and deciding where to place it has significant implications. While this is an optional step, the planning department would like to help inform your choices.
Step 2: Submit a Complete Application. When you are ready, submit a building permit application with all required plans and documents. Lot surveys are required if proposed setbacks are less than 5 feet. Having all the necessary documents will help us expedite the review process and minimize the need to contact you, your designer, or your contractor for additional information needed to complete the review.
Step 3: Ministerial Review. All ADUs are subject only to a staff-level review for compliance with applicable laws and standards. Typically, the review involves:
- Planning Division to ensure that all applicable development standards are met.
- Building Division to ensure that all California building and energy code requirements are met. Applicants who utilize one of the permit-ready Garden Cottage Program plans to qualify for an expedited review given that all plans have been pre-plan checked.
- Engineering Division (if applicable) to ensure that grading ordinance requirements are met for any ADU built on a slope or require onsite grading. Staff will review conditions and will also confirm that the ADU will not infringe on existing easements.
*Note that ADUs are still subject to review and approval by other public agencies such as East Bay Municipal Utility District (EBMUD), Central Contra Costa Sanitary District (Central SAN), and San Ramon Valley Fire Protection District (SRVFPD).
Step 4: Building Permit Issuance. When all of the submitted plans have been reviewed and approved, your permit will be ready for “issuance.” At this point, one of Danville’s Permit Technicians will contact you to pick up your permit and pay the applicable fees. Having a building permit in hand provides an “authorization to proceed” with construction.
Step 5: Construction and Inspections. Town inspectors will be onsite at various phases of building construction to ensure that the structure is built according to plan. Note that the person performing the work has the obligation to schedule all required inspections.
Step 6: Building Occupancy. Once construction has passed all the required inspections and obtained approvals from outside agencies, then a Certificate of Occupancy can be issued. You or your contractor may arrange to pick up the Certificate of Occupancy at the Danville Permit Center. Once your certificate is in hand, the ADU may be occupied.
510 La Gonda Way
Danville, CA 94526
Civil Engineering Associate
We hope this quick reference guide helps you out in your ADU project. Part of our service if you build with us is the full-service of our in-house permit technician where we handle your permits processing on your behalf with no mark-ups.
If you’re interested in building with ADU.Works, please don’t hesitate to book a consultation with us or give us a quick call through our number (408) 610 3005. We’ll gladly discuss the specifications of your permits processing and accommodate any question you may have. Our team looks forward to hearing from you.