The City of Orinda has a webpage describing its ADU Regulations which are covered in Ordinance 17-03

see website


How is Orinda dealing with ADUs?

Rather than continue to rely on the ADU Statute, which contains relatively minimal standards, the City adopted a new ADU ordinance in compliance with State law. The new ordinance (17-03) restores some additional local control over ADU applications and provides clarity regarding the standards that apply to the City’s review of such applications. Ordinance 17-03 repeals the City’s existing Second Unit ordinance and incorporates the changes required by State law.

New Regulations

The new State laws contain specific requirements for the City’s review of accessory dwelling units. These requirements differ depending on whether a unit is 1) wholly contained within an existing structure; 2) new construction is involved; or 3) the lot contains an existing single-family residence. To facilitate review, Section 17.3.4 of the OMC classifies ADUs into three categories. These categories are as follows:

  1. Category 1: ADUs do not create new square footage.
  2. Category 2: ADUs create new square footage on a lot with an existing single-family residence, either within the residence or in an accessory structure.
  3. Category 3: ADUs are built in conjunction with a new single-family residence.


For additional information or questions regarding ADUs, please contact Senior Planner, Mayank Patel, via email at or by phone at (925) 253 – 4212.