Accessory Dwelling Units (ADUs)

Accessory dwelling units (ADUs) are also known as granny or in-law units.  In Cotati, most residential properties are eligible to construct a least one ADU. ADUs may also be placed on multifamily properties and in mixed-use zoning districts.

ADUs can come in many shapes and sizes, but an ADU is always a self-contained home that is secondary to the the primary residence and legally part of the same property. They generally fall into one of the following categories:

ADU

ADU RESOURCES

Napa Sonoma ADU Center
Provides a wealth of resources for homeowners considering  an ADU or JADU. Explore their website to find useful resources such as designs and floor plans, an ADU Handbook, helpful webinars, an ADU calculator, and stories from people that have built ADUs.

Homes for Sonoma
Nonprofit developer creating quality workforce housing options that support a safe and sustainable community, with an emphasis on ADUs.

HCD's Accessory Dwelling Unit Handbook
The State Department of Housing and Community Development provides a handbook that includes explanations and interpretations of California ADU Laws.

Casita Coalition's ADU Finance Guide
Nonprofit organization advancing housing solutions has prepared a financing guide for homeowners looking to build ADUs.


Napa ADU
  • Detached: Free-standing structure, such as a backyard cottage. This can include a legally-existing garage or other accessory structure that is converted to an ADU.
  • Attached: Shares at least one wall with the primary residence and is an addition of space to the primary residence's structure.
  • Interior Conversion: Built from existing space in the primary residence (such as an attic, basement, or garage).

On lots of less than 1/2 acre in size, the maximum size allowed for ADUs is 850 square feet for studio or 1 bedroom units, and 1,000 square feet for 2+ bedroom units. On lots of 1/2 acre or more, the maximum ADU size is 1,200 square feet. ADUs are subject to height and property line setback limitations as well. Refer to the ADU Standards Overview for a basic summary of key development requirements for all types of ADUs. For a full description of standards for ADUs in Cotati, refer to the ADU Standards Summary.

Most single-family residential properties are also eligible to construct a Junior ADU (JADU). JADUs are limited to 500 square feet and may only be located within the walls of an existing or proposed single-family residence. JADUs must include a separate entrance from the primary residence and an efficiency kitchen, but may share a bathroom with the primary residence.

ADU 2