Navigating California’s ADU Regulations: What You Need to Know

Looking for affordable housing in California? So is everyone else. With skyrocketing prices and limited inventory, the state’s housing market has been in a state of crisis for years. 

To counteract these shortages, the state has been gradually introducing provisions to accommodate Accessory Dwelling Units (ADUs) since 2016. This has been a game-changer, opening up more possibilities for homeowners who want to generate extra income, house family members, or provide affordable rental options in their communities. Renters also stand to benefit by gaining access to more diverse and affordable housing choices.

Many of these changes went into effect in 2024 and could play a key role in helping you find or build your new dream home. Here’s everything you need to know.

Owner-Occupancy No Longer Required

Previously, ADU regulations required owners to live on-site to build an ADU. That changed in 2020 when SB 13 banned the owner-occupancy rule. The trouble is that the bill only extended protection to owners until 2025.

The new AB 976 bill permanently eliminates the owner-occupancy requirement, allowing owners to build ADU rental properties and generate passive income without living on-site. 

However, this change does not apply to junior accessory dwelling units (JADUs), which still require owner occupancy. 

More Flexible Homeownership Structures

One of the most groundbreaking changes in California’s ADU regulations is that it allows for “condo-ization.” Now, homeowners can sell detached ADUs separately from the main property. 

This opens up a world of possibilities for owners and buyers. For homeowners, condo-ization allows them to create more flexible home structures, offset costs, and generate additional income. Buyers also stand to benefit—particularly those who cannot afford a traditional home or others who simply do not need a lot of square footage. 

Additional ADU Regulations You Should Know About

AB 976 allows you to build and rent an ADU without living on-site. “Condo-ization” enables you to sell it. But there are additional ADU regulations you’ll want to know about. 

ADU Type

In California, residential property owners are allowed to build one 800-square-foot ADU, regardless of the size of the lot or the main structure (so long as it is no taller than 16 feet). You should also know that if you have enough space, the state allows you to build: 

  • One attached ADU
  • One detached ADU
  • And one JDU

ADU Size

If you plan to build a one-room ADU, cities in California are required to allow a minimum size of 850 square feet. If the ADU has two or more bedrooms, the minimum size is 1,000 square feet. While cities can allow homeowners to build bigger, they cannot impose minimum sizes less than the state-mandated minimums. 

In cities that have not adopted ADU ordinances, the state sets default size limits for ADUs. The maximum allowed size for detached ADUs is 1,200 square feet, and for attached ADUs, it is limited to 50% of the main building’s square footage.

However, it’s important to note that regardless of these default limits, every California homeowner is entitled to build an ADU of at least 800 square feet. This means that even if your main building is small and the 50% rule would limit your attached ADU to less than 800 square feet, you are still allowed to build an 800-square-foot ADU.


A “setback” is the minimum distance a structure must be set back from the property line. 

In California, setbacks can be up to four feet from the side and rear property line. Cities like San Diego do not impose minimum setbacks. Others have specific zoning codes and building regulations for how far a structure must be set back from the front property line. However, California has a provision that can override local front setback requirements if they prevent a homeowner from building an 800-square-foot ADU. 


Every California homeowner is entitled to build an ADU that is no more than 16 feet tall and up to 800 square feet in size. However, you may be entitled to make a taller structure sometimes.

If you live within a half mile of public transit, you are entitled to build an ADU that is 18 feet tall. The same rule applies to multi-unit properties that are two stories high. A height of up to 25 feet is allowed if the ADU is attached to the main structure. 

Quality & Compliance: These Are Our Specialities 

ADU regulations in California are complex. With nearly three decades of experience in building custom ADUs, the team at Specialty Home Improvement has the knowledge and expertise to guide you through the process. Whether you want to create additional living space for your family, generate rental income, or increase the overall value of your property, we can help. Contact us today!