An Accessory Dwelling Unit (ADU) is a second, smaller dwelling that can be built on a property already occupied by a single-family home or an apartment building. ADUs provide independent living for one or more people, including permanent facilities for living, sleeping, eating, cooking, and sanitation. ADUs must have an exterior entrance and be placed on a permanent foundation. New state laws that went into effect in 2020 make ADUs easier to develop.
There are several types of ADUs, as shown in the image above.
- ADUs can be separate structures, detached from the main residence (detached ADU) or an addition to the residence (attached ADU).
- ADUs can also be internal to the residence through the conversion of an existing bedroom, basement, attic, or other room in the house.
- Existing structures, such as garages or accessory structures, can also be converted to become an ADU.
- An ADU that is inside the existing home, is no more than 500 square feet, has access to a bathroom, a sink, and a microwave or hot plate, and has a separate entrance is called a Junior ADU.
A building permit is required to build an Accessory Dwelling Unit. If your ADU is larger than 800 square feet or taller than 16 feet, you must submit your project to Planning for review and approval prior to getting a building permit.
Please contact Planning staff before submitting an application to build an ADU. Staff can help you determine if Planning approval is needed or whether you can simply apply for a building permit. They can also help answer questions about size, setback, and height standards, as well as whether any objective standards apply.
- ADU Application Checklist
- Accessory Dwelling Unit Ordinance
- City of Folsom's ADU Process
- Frequently Asked Questions
- Historic District Boundary
- ADU Parking Requirement Map
- ADUs and Electrical Service
- ADU Design Workbook - Part I: The Basics
- ADU Design Workbook - Part II: The Historic District
- Sample JADU Deed Restriction Form
- Apply online - Visit the City's ePermit Center
Visit the city's ePermit Center to apply online.