While ADUs can be a great solution to the housing crisis in California, navigating the laws and regulations surrounding them can be overwhelming. This blog post will provide an overview of California ADU laws and regulations to help you understand if you can build an ADU on your property.

California has long been known for its expensive housing market, which has left many residents struggling to find affordable housing. One solution that has gained popularity in recent years is the construction of Accessory Dwelling Units (ADUs), also known as granny flats, in-law units, or secondary units. These units are small, self-contained living spaces located on the same lot as a primary residence. They can provide a way for homeowners to create additional housing options for family members and renters, or even as a way to generate rental income.

Types of ADUs

Before diving into the regulations, it’s essential to understand the different types of ADUs allowed in California. There are two main types of ADUs: attached and detached.

Attached ADUs are connected to the primary residence and share at least one wall with the main house. These units are often created by converting a garage or part of the existing home.

Detached ADUs are separate structures on the same lot as the primary residence. These units are created by building a new structure in the backyard.

California ADU Laws and Regulations

In 2016, California passed legislation to encourage the construction of ADUs throughout the state. The  law was updated in 2019 to encourage accessory dwelling unit construction further and make it easier for homeowners to build them. Here are some of the key regulations that govern ADU construction in California:

ADUs are allowed on most residential lots.

In California, accessory dwelling units are allowed on most residential lots as long as they meet specific zoning requirements. Local zoning ordinances may restrict the number of ADUs permitted on a lot, as well as their size and location.

ADUs can be up to 1,200 square feet.

Accessory dwelling units in California can be up to 1,200 square feet for detached units and up to 50% of the existing living area for attached units. This means that if your primary residence is 2,000 square feet, your attached ADU can be up to 1,000 square feet.

ADUs must include a kitchen and bathroom.

ADUs in California must include a kitchen and a bathroom. The kitchen must have a cooking facility with appliances, a sink, and countertops.

ADUs may require additional parking.

Local zoning ordinances may require additional parking for ADUs. However, the 2019 law prohibits cities and counties from requiring parking if the accessory dwelling unit is within half a mile of public transportation, in a historic district, or if the ADU is part of the primary residence or an existing accessory structure.

ADUs may require a permit.

In California, ADUs may require a building permit. Homeowners should check with their local planning department to determine what permits are needed for their project.

ADUs may be subject to local design standards.

Local governments may have design standards for ADUs that dictate their appearance and features. Homeowners should check with their local planning department to determine what design standards apply to their projects.

Can I Build an Accessory Dwelling Unit on My Property?

Now that you understand the regulations governing ADU construction in California, you may wonder if you can build an ADU on your property. The answer depends on several factors, including:

Your property’s zoning.

To build an accessory dwelling unit, your property must be zoned for residential use. If your property is zoned for commercial or industrial use, you may not be able to build an ADU.

The size of your property.

The size of your property is another factor that can impact your ability to build an accessory dwelling unit. While ADUs are allowed on most residential lots, local zoning ordinances may restrict the maximum number of units permitted on a lot and their size. For example, some cities may limit the total square footage of all structures on a lot, impacting your ability to build a detached accessory dwelling unit.

Your property’s layout.

The layout of your property can also impact your ability to build an accessory dwelling unit. For example, if your property has limited space or is oddly shaped, finding a suitable location for an ADU may be challenging. Additionally, if your property is located on a steep slope or has other topographical challenges, it may be more difficult to build an accessory dwelling unit.

Your budget.

Building an accessory dwelling unit can be expensive, and the cost will depend on various factors, including the size and design of the unit, the cost of materials and labor, and any site preparation that needs to be done. Before deciding to build an ADU, it’s crucial to have a budget in mind and to research the costs involved.

Your willingness to navigate the permitting process.

Building an ADU can require obtaining permits from local government agencies, which can be a complex and time-consuming process. Before deciding to build an ADU, it’s essential to understand the permitting process and to be prepared to navigate it.

An ADU can be a great way to create additional housing options on your property, but it’s important to understand the laws and regulations governing their construction. By familiarizing yourself with California ADU laws and regulations, you can determine if building an ADU is viable for your property. 

Be sure to consult with your local planning department to determine the specific requirements and restrictions that apply to your property, and to work with a qualified contractor to ensure that your accessory dwelling unit meets all applicable codes and standards. With careful planning and preparation, building an accessory dwelling unit can be a rewarding and worthwhile investment in your property and community.