Accessory Dwelling Units

An accessory dwelling unit (ADU), sometimes called a “second unit” or “in-law unit”, is a self-contained living unit on the same property as a primary residential building. These units generally include a living and sleeping area, kitchen, and bathroom. They can be detached from or attached to a primary dwelling. You can also create an ADU by converting a garage or existing space in a home into a separate living unit. Most Benicia residents can imagine many ways to use an additional unit on their property: as a rental unit, or home for an elderly relative, a caregiver, or an older son or daughter living at home. We are excited to let residents know that the City of Benicia has made it easier than ever to add one of these units to a residential property.

Can I build an ADU on my property?

ADUs are allowed in all districts where single-family or multifamily dwellings are permitted, which includes all residential and mixed-use districts. You can add an ADU to a lot with an existing dwelling or include an ADU in your plans for a proposed new single-family or multifamily dwelling.

There is no minimum lot size necessary for ADUs. The size of your existing home will not prevent you from adding an ADU, as you may construct an ADU up to 800 square feet regardless of the size of your home.

What are Benicia’s ADU rules?

Benicia’s ADU regulations can be found in Municipal Code Section 17.70.060 (entitled Accessory Dwelling Units). These regulations went into effect on March 6, 2020 and implement revisions to California state law that the legislature adopted in 2019.  The Benicia Municipal Code can be viewed online by clicking here.

The City must act on an application for an ADU within 60 days of receiving it. For an ADU that meets the requirements of the ADU Ordinance, no design review or public hearing is required.

Benicia’s ADU regulations specify maximum size, height, setback, and other development. ADUs within the Downtown or Arsenal Historic Districts must follow special design standards. However, certain types of ADUs may be exempt from most development and design standards. Please consult the Planning Division for guidance on which standards apply to your project.