Accessory dwelling units (ADUs)

Accessory dwelling units (ADUs) go by many different names, including in-law units, granny flats, or backyard cottages. An ADU is an additional, small home that you can build on your property. They have a kitchen, a bathroom, and a separate entrance. 

There are different types of ADUs, including: 

• Attached ADUs: Attached ADUs are attached directly to the main house.
• Detached ADUs: Detached ADUs are a separate buildings located on the same property as the main house.
• Junior Accessory Dwelling Units (JADUs): JADUs are smaller versions of ADUs. They are often created by converting an existing bedroom. They do not need to have a full kitchen, but they must have a wet bar.

Like other parts of the Bay Area, Marin County is experiencing a severe housing shortage. The creation of ADUs is one solution we can use to help address our affordable housing challenges. Benefits of building an ADU include: 

• Rental Income: You can rent an ADU to a tenant. This will provide both much-needed housing and generate a steady source of income.
• Housing for Caregivers/Loved Ones:  ADUs are often used to house caregivers for people who need support or medical care.
• Increase in Property Value: ADUs can increase the value of your property by providing more living space. 

Learn about how Don and Jane utilized cost-saving strategies to create an affordable ADU for a local family.

You can also find other success stories on ADUMarin.

If you're interested in building an ADU in unincorporated Marin, we encourage you to get in touch with our Planning team. You can also find helpful resources on ADUMarin.

County Regulations

You can also learn more about ADU regulations in unincorporated Marin in Section 22.32.120 of the Marin County Development Code.

ADU Legalization Program

Per AB2533  this program helps residents legalize and improve the safety of existing unpermitted accessory dwelling units (ADUs) or junior ADUs (JADUs) built before January 1, 2020. To learn more and get started, follow the step-by-step instructions on the ADU Legalization Program page.

Are you interested in renting out your ADU? Here are a couple of helpful resources:

• Renting in Marin page providing information about tenant laws that may apply to your unit.
• ADUMarin Renting & Move-in page detailing step-by-step considerations.
• Guide on Fair Housing Laws Applied to ADUs prepared by the Fair Housing Advocates of Northern California (FHANC) to provide information on how property owners can navigate legal protections while maximizing the potential of ADUs to foster diverse, accessible and inclusive communities.