Santa Monica ADU Regulations & Zoning

In Santa Monica, an attached ADU can be a maximum of 1,200 square feet or 50% of the primary dwelling unit size, whichever is smaller..

In Santa Monica, an ADU is usually limited in height to 16 feet. However, if the ADU is positioned over an existing structure, like a garage, or part of a two-story structure, specific zoning rules may allow for an ADU of up to 25 feet tall.

Yes, you are allowed to build a 2-story ADU in Santa Monica, but the standard 16-foot height restriction is usually insufficient for a viable 2-story building. If zoning variances allow for a greater height limit, a 2-story ADU may be much more feasible.

Since only one ADU is allowed per single-family property in Santa Monica, it is not possible to get approval for two ADUs attached to each other. However, since you can build up to two detached ADUs on multifamily property, you can get approval for two ADUs detached from the main structure but attached to each other into one big structure as long as all other zoning and building rules are observed.

No, a JADU by definition is built into existing space within the primary dwelling unit. It would be a contradiction in terms to have a JADU attached to an ADU.

Yes, you are allowed to build an ADU with a roof deck in Santa Monica. However, keep in mind that the required safety railing will count towards the total height limit of the ADU. The minimum safety railing height on a roof deck in California is 42 inches.

Santa Monica requires that new ADUs generally conform to the external appearance of the main dwelling unit — color, material, roof pitch, roofline, door and window style, and other general characteristics to help the ADU blend in with the primary dwelling unit and the rest of the neighborhood.

A soils report is usually required for a new ADU build in Santa Monica, especially if the area is noted for groundwater issues, seismic activity, or soft soil.

Plans must be submitted to the City of Santa Monica Permit Service. They must then be reviewed by a variety of departments to check for compliance with the California Building Code, zoning, fire safety, and Title 24 energy standards. The plans may be returned several times for questions, corrections, and revisions. The process takes approximately 8-10 weeks.

An ADU is not required to have a separate water or electrical meter. You can opt for the ADU to share service with the main dwelling unit. However, you can request separate water or electrical meters from the City of Santa Monica.

Santa Monica does not automatically assign a new ADU its own address. However, it may assign the ADU a new address if it is intended for rental or independent occupancy.

Low Impact Development (LID) is an approach to land development or redevelopment that seeks to preserve and conserve onsite water quality and natural features, with minimal detrimental effect to local waterways and ecosystems. Santa Monica may require LID fees for larger ADUs.

Santa Monica does not impose rent control on dwellings constructed after January 1, 1995. This means most new-build ADUs are exempt. However, if the primary dwelling unit is subject to rent control, it might apply to the ADU as well.

While encouraging the use of electric appliances for efficiency and sustainability, Santa Monica does not prohibit gas appliances in new ADUs.

In Santa Monica you are only required to install sprinklers in a new ADU if the primary dwelling unit has them as well. You may also be required to install them if the ADU is located within a special fire hazard zone.