Can an ADU Be a Primary Residence?

ADU's as a Primary Residence

An accessory dwelling unit (ADU) can be utilized as a primary residence if certain conditions are met. While ADUs are typically considered secondary units, some municipalities in California—including Los Angeles, San Diego, San Francisco, and Palm Springs—allow them to serve as primary residences. This depends on local zoning laws and regulations.

What Is an ADU and How Does It Function?

An ADU is a secondary housing option built on the same lot as the main dwelling unit, and can be either attached or detached. These compact living spaces have surged in popularity, especially in urban areas like San Diego, because they offer an affordable living option in densely populated regions.

Typically, an ADU must be equipped with all essential amenities, including a kitchen, bathroom, and living area. They are designed to function as self-contained living quarters, making them suitable for full-time occupancy.

Exceptions: When Can an ADU Be a Primary Residence?

While they typically serve as additional living spaces to a primary residence, ADUs can be used as a primary residence in certain circumstances. An ADU can be a primary residence when it’s:

Purchased as a Condo

In high-density areas like San Diego, an ADU can be purchased as a condominium, allowing it to be used as a primary residence. This option provides flexibility for homeowners seeking to maximize their living space or invest in real estate while adhering to local regulations.

Converted as a Secondary Unit

A secondary unit can be converted into a primary residence, but this is only permissible if the main dwelling was established prior to the construction of the ADU. This rule ensures that the primary home remains the focal point of the property while still allowing for the ADU to serve as a living space.

A Temporary Living Solution

Homeowners may be permitted to reside in the ADU temporarily while the main house is under construction or renovation—but this is dependent on local zoning laws. This arrangement can provide a practical solution for those who need immediate housing during the building or renovation process. It is essential to follow any specific laws regarding this to ensure compliance.

California ADU Regulations: Can You Build an ADU Before the Main House?

The California statewide ADU laws define an ADU as an accessory unit with complete living facilities located on a lot with a proposed or existing primary residence. This means that the primary dwelling must be either existing or under construction before ADU permits are issued, and they are not allowed on vacant lots without a primary residence. There are exceptions and special cases when an ADU can be built before the main structure.

• Temporary Use Permits allow temporary occupancy of an ADU during construction of the main residence. This is often subject to strict time limits and requires demonstrating active progress on construction of the main house.
• Lot Splits: A recent California law allows certain single-family lots to be split, potentially allowing for separate ownership of what was originally planned as an ADU, resulting in an ADU becoming the primary residence on its own lot.
• Scenarios where there is a rebuild due to a disaster or renovation can permit temporary occupancy of an ADU as the main residence.
• Rural or agricultural zones usually have more lenient rules for agricultural worker housing.

ADU regulations are complex and constantly changing. Homeowners should consult directly with a local planning department and work with a local company that has extensive knowledge of this project type.

San Diego-Specific ADU Regulations and Trends

San Diego has embraced ADU construction to address housing challenges. The county and its cities have implemented a more streamlined approval process and progressive policies, allowing multiple ADUs on single-family lots and offering incentives like fee waivers and pre-approved plans.

Popular neighborhoods, like North Park and coastal areas in Encinitas, have seen a surge in ADU development. ADUs have become increasingly attractive in the high-cost housing market because they offer more affordable homeownership options, potential rental income, and flexibility for multigenerational living.

Local initiatives such as the San Diego ADU Bonus Program, ADU Acceleration Program, and Housing Solutions Program provide additional support and incentives for ADU construction. These efforts reflect a shift in urban planning priorities, focusing on infill development and diverse housing options to combat the region’s housing shortage and affordability issues.

Benefits and Challenges of Using an ADU as a Primary Residence

A common way homeowners use ADUs as a primary residence is by renting out their main house and living in their ADU. By weighing the benefits and challenges of using an ADU as a primary residence, homeowners can make an informed decision if this is the right course of action for their situation.

Contact Better Place Design & Build for Personalized ADU Solutions

At Better Place, our experienced team guides you through the entire ADU process. From design to construction to permitting—we are committed to bringing your ADU vision to life. Ready to explore your options? Schedule your free consultation now.