ADU Regulations

Owner Occupancy

One of the reasons ADUs are so attractive for investors is that there is a moratorium on owner-occupancy requirements. You can lease out both the main dwelling and your ADU as long as it is constructed prior to 2025. With a housing shortage in our state, regulations are continuously evolving towards encouraging ADU construction.


Recent 2020 California law allows a companion unit to be added to certain multi-family zoned properties. This law allows for a maximum of 2 ADUs per property with an existing multiple unit structure. The added units can be within one structure or constructed as independent ADUs.

Application Review

Building departments have been required to respond to a granny flat application within 60 days substantially reducing time for final approvals. This limit used to be 120 days for the initial review. We want to make it easy for you! OneStop ADU's team takes your project through the permitting process at no additional cost.

Size & Setbacks

No minimum lot size required in CA. Local municipalities are allowed to pass additional regulations but must allow a companion unit of less than 850 sq ft or may set a maximum of 1000 sq ft for ADUs with 1 or more bedrooms with only 4 feet side and rear setbacks.


HOAs (Homeowners Associations) and CC&Rs (Covenants, Conditions & Restrictions) cannot prohibit development of backyard homes. We offer three finish options- Contemporary, Craftsman and Spanish/Mediterranean to easily comply with requirements for specific exterior styling.


There are no parking requirements for properties located in a “transit priority zone” (within 1/2 mile of public transit). Certain jurisdictions may require one spot per backyard home while others may waive these requirements.


OneStop ADU is educated on the crucial thresholds for square footage that will trigger higher costs such as sewer connection and impact fees. To encourage homeowners to build casitas, many development fees have been waived. For example, the City of San Diego has waived all development impact fees for granny flats regardless of size.


According to updated guidance from the HCD (California Department of Housing and Community Development), solar power is required for all newly built, non-manufactured detached ADUs as per Title 24.  Per the California Energy Commission (CEC), the panels can be installed on the ADU or on the primary dwelling unit.  Unlike most others in the industry, OneStop ADU includes the cost of solar in our construction price for your ADU based on requirements for Climate Zone 7.

We Want to Hear From You

Contact OneStop ADU today. We serve owners and investors in the entire county, including San Diego, Chula Vista, Oceanside, Carlsbad, and the surrounding areas.

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