ADUs in California: A Comprehensive Guide

ADUs in California: A Comprehensive Guide

An accessory dwelling unit (ADU) is a secondary housing unit on the same lot as a single-family home. California is one of the most progressive states when it comes to ADUs, with a number of laws and regulations in place to encourage homeowners to build them.

ADUs can be used for a variety of purposes, such as rental income, in-law units, or home offices.

They can be detached from the main house or attached, such as a garage conversion.

Building an ADU in California can be a great way to leverage your property and create additional income. However, there are a number of things to consider before taking on such a project. This guide will cover everything you need to know about ADUs in California, from the laws and regulations to the cost and process of building one.

What is an ADU?

An ADU is a secondary, self-contained residential accommodation located on the same residential lot as a main residence. ADUs can be permanently attached or detached, and they provide the occupant with their own independent living space, which can include its own bathroom and kitchen facilities.

Moreover, ADUs are usually constructed within a preexisting structure, such as a converted garage or attic space. ADUs are becoming increasingly popular in California and other states, as they provide homeowners with an opportunity to access additional income, accommodate aging relatives, and provide usable space in constricted urban markets.

Who can build an ADU in California?

In California, anyone who owns a single-family home is allowed to build an ADU. However, there are certain building permit requirements that must be met before the project can begin. These include zoning, fire, and occupancy codes.

In addition, if the lot is subject to a homeowners’ association, those regulations must also be adhered to. Local jurisdictions may also have their own regulations, so be sure to check with your local building and planning department before breaking ground.

When can ADUs be built?

The State of California has adopted a series of laws to encourage the construction of ADUs, including the passage of Senate Bill Five Three in 2016. These laws relax previous restrictions and allow for streamlined approval processes and waived fees.

As a result, the timeline for getting an ADU approved is now much shorter and ADUs can be built with relative ease. Of course, local regulations still apply, so be sure to check your local building and planning department for specific rules and regulations.

How do ADUs affect property values?

In general, the construction of an ADU is thought to have a positive effect on a home’s property value. For one, ADUs can provide the homeowner with an additional source of income—which can, in turn, help pay for other necessary improvements.

Furthermore, an ADU often adds additional living space and bolsters the home’s desirability due to its increased capacity to accommodate lengthy visits from friends and family members. Moreover, ADUs are also viewed as a sustainable housing option, which can promote further appreciation in the market value.

How do I get started building an ADU?

Building an ADU is a complex process and will likely require hiring a contractor. The first step is to contact your local building and planning department to determine if your property is eligible. Then, you will need to get all the necessary permits.

After that, you will need to secure the necessary materials and hire a contractor. Once the construction is complete and approved, you will need to complete the utility hookups and make sure the living space is up to code.


ADUs are a great way to leverage a single-family home and create additional income. California has adopted a number of laws and regulations to encourage the construction of ADUs and make the process easier and faster.

Even so, there are still a number of steps to consider before embarking on such a project, from securing a permit to hiring a contractor. It’s important to do your research, understand zoning regulations and occupancy codes, and consult with an experienced contractor before beginning.

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