There are many reasons you may want to build an accessory dwelling unit (or ADU) on your property in the great state of California. Maybe you want to create an additional living space for a family member. Or you may want to rent it out on a long-term basis for someone who can call it home, all while increasing your property’s value.

Regardless of your reasons for adding an ADU to your property, the process for doing so remains the same, and you’ll always need to obtain permits before you can start building your ADU.

In this guide, we’re going to walk you through exactly what it takes.

An ADU permit is a formal issuance from a local building department that authorizes the construction of an ADU on a residential property. It confirms that the plan for the ADU’s design and location meets all of the building codes, safety standards, and zoning regulations that are set by the local jurisdiction.

Under California state law, not just any building added to a property counts as an ADU. Instead, the ADU must have certain amenities to classify it as a complete, independent living unit. At a bare minimum, an ADU has to include permanent provisions for:

The exact specifications vary by local jurisdiction, and your ADU will need to meet all of those that apply to your property. To find out what exactly is required of an ADU in your jurisdiction, you should consult your local building department.

The process varies depending on the jurisdiction, but building an ADU in California typically requires these main permits:

The purpose of these permits is not just to ensure that local laws and community standards are followed. They’re also designed to protect you as a homeowner by ensuring that your ADU meets all safety and zoning standards so you won’t run into any problems down the road.

An ADU is a secondary dwelling unit located on the same property as an existing home or dwelling. In essence, an ADU is an independent home (usually smaller than the main home) that has its own entrance and full bathroom, kitchen, and living space.

There are two primary types of ADUs, and the process for obtaining permits for each can vary. Detached ADUs stand separately from the main home. Attached ADUs share a building wall with or are inside the main home and can be no larger than 50% of its size. There are also converted ADUs, where an existing structure like a garage is renovated into an ADU.

In California, ADUs can be between 150 and 1,200 square feet, and you can build one detached ADU and one attached ADU on each property that has a single-family dwelling. For multi-family properties, you can build up to two detached ADUs and one attached ADU.

California also has a separate legal definition and requirements for Junior ADUs (or JADUs). In California, a JADU must be within the walls of an existing home, and it is not considered to be new housing, unlike an ADU. JADUs have a smaller maximum size of 500 square feet.

One of the reasons people like to build ADUs on their property is to help increase the property value. Does this mean that your property taxes will go up? The short answer is yes, but an ADU is the most tax-efficient way to add square footage because it does not trigger a reassessment of your entire property in California.

As a golden rule, you can expect your property taxes in California to increase by 1% to 2% of the total cost of construction annually. So, if your ADU costs $200,000 to build, you may have to pay around $2,000 extra in property taxes each year.

The application process for getting an ADU permit in California depends on the jurisdiction in which you’re building the ADU. As a general rule, you’re going to need to provide the following documentation:

Your jurisdiction will review your ADU submission within 60 days and provide their initial comments. The full permitting process typically takes three to four months from your first submittal date.

Some jurisdictions offer pre-approved ADU plans to help streamline the permitting process. While you can purchase pre-made plans from various manufacturers, check with your local jurisdiction to confirm which plans they accept.

Samara takes the guesswork out of getting permits for an ADU. We take care of designing, building, and permitting a Backyard ADU with five expertly prefabricated floor plans to choose from.

Samara’s efficient supply chain and experienced team allow homeowners to get a move-in-ready ADU with around 30 days of on-site labor.

Schedule a 15-minute call with a Samara specialist to learn more about our Backyard ADU and how incorporating it into your property can benefit you. Our specialists are also available at 650-420-2607 to answer any questions. Samara also works with developers and hospitality providers to add high-quality, prefab housing to properties.

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