Accessory Dwelling Units (ADUs) and Junior ADUs (JADUs) in the Town of Colma

Welcome to the Town of Colma's official resource for Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs)! Whether you're a homeowner looking to create more space for family, generate rental income, or contribute to housing solutions in our community, this page will guide you through everything you need to know.

What is an ADU?

An Accessory Dwelling Unit (ADU) is a secondary residential dwelling unit that provides complete independent living facilities for one or more persons and is located on a lot with a proposed or existing single-family primary residence or a multifamily dwelling. These are also commonly known as in-law units, granny units, or second units. An ADU also includes an efficiency unit and a manufactured home, as defined in Section 18007 of the Health and Safety Code.

An ADU can be:

  • Detached: A separate structure from the main home
  • Attached: Shares a wall with the main home
  • Converted: From existing space, like a garage or basement

What is a JADU?

A Junior Accessory Dwelling Unit (JADU) is a residential unit that is no more than 500 square feet of interior livable space in size and contained entirely within an existing single-family residence. A JADU may include separate sanitation facilities or may share sanitation facilities with the existing structure.

adu

Benefits of Building an ADU or JADU

  • Flexible living arrangements for family, caregivers, or renters
  • Rental income potential
  • Increased property value
  • Supports local housing needs

Who Can Build an ADU or JADU in Colma?

If you own a residential property in Colma, you may be eligible to build an ADU or JADU. Both are permitted in all residential and mixed-use zones. However, JADUs are only allowed on single-family lots with an existing or proposed single-family home.

Development Standards

Below are key standards under California state law. For more information on development standards, please refer to the State of California Department of Housing and Community Development 2025 ADU Handbook.

Size Limits

  • Attached and detached ADUs: Up to 850 square feet of interior livable space for a studio/one-bedroom; up to 1,000 square feet of interior livable space for two or more bedrooms
  • JADUs: Maximum 500 square feet of interior livable space

Setbacks

  • Rear and side setbacks: no more than four (4) feet for newly constructed attached or detached ADUs
  • No setbacks: none required for ADU conversions or rebuilds that are constructed in the same location and to the same dimensions as an existing structure
  • Must meet fire and safety requirements: single-family conversion ADUs and JADUs that qualify as State-Exempt

Height Limits

  • Attached ADUs: Up to 25 feet or the maximum allowed by the underlying zoning, whichever is lower. Attached ADUs may not exceed two stories
  • Detached ADUs: Up to 16 feet
  • Detached ADUs within a ½ mile walking distance from a major transit stop or high-quality transit corridor: Up to 18 feet plus 2 feet to accommodate a roof pitch
  • Detached ADUs on a lot with a multi-family, multi-story dwelling: Up to 18 feet

Parking

  • One space per ADU is required
  • No additional parking is required if the ADU is:
  • Within ½ mile of public transit
  • Part of an existing structure (conversion ADU)
  • In a historic district
  • Within one block of a car-share
  • A State-Exempt ADU
  • 500 square feet in size or smaller

Submittal Requirements and Process Time

Applications for ADUs and JADUs must be submitted to the Planning Department and reviewed as part of the established building permit process. The following checklists serve as an eligibility screening by the Planning Department to ensure the proposed project meets development standards per state law before creating building plans and submitting an application.

ADU Planning and Zoning Standards Checklists

JADU Planning and Zoning Standards Checklists

The Town of Colma is committed to streamlining the ADU process. ADU/JADU applications are reviewed ministerially and approved or denied within 60 days after a complete application is submitted. The Planning and Building Department will determine that an ADU or JADU application is complete within 15 business days of receipt and will notify the applicant in writing of the decision. If an application is incomplete, the applicant will receive a list of missing items and instructions for completing the application in the written notice.

Applications for detached ADUs using pre-approved plans from the Colma ADU Plans Gallery are reviewed ministerially and approved or denied within 30 days of submission of a complete application. For more information, please visit our AB 1332: Pre-Approved ADU Plans Program webpage (coming soon).

Resources and Assistance

Helpful Links

Do you have questions? We’re here to help! Contact the Planning Department at www.planning.colma.ca.gov or call (650) 757-8888 to schedule a consultation or learn more about how ADUs and JADUs can work for you.

Together, we can build a more flexible, inclusive, and sustainable Colma.

Close window