ADU Basics
Start Here to Learn about ADUs in Los Angeles & Ventura County
Just starting to think about building an accessory dwelling unit (ADU) on your property in Los Angeles or Ventura County? You probably have a lot of questions…
What is an ADU? Is an ADU the same thing as a granny flat, casita, guest house, in-law suite, or backyard cottage? What can I build on my property, and where? How do I begin the process? Should I talk to an architect or a contractor first, or maybe start with financing? How much will an ADU cost?
We’re here to guide you through the basics! Start with this overview to familiarize yourself with key terminology and understand what California laws require local governments to allow when it comes to ADU development.
What is an ADU?
In construction and real estate, an ADU (Accessory Dwelling Unit) is a secondary housing unit located on a property zoned for single-family or multifamily residential use. These units can be detached from the main home (like a new stand-alone structure in the backyard), attached (such as a garage conversion), or part of the existing home (like an upstairs unit). ADUs typically include a full kitchen, a bathroom, and a private entrance.
Often called “granny flats,” “in-law units,” or “backyard cottages,” ADUs have become a popular solution to urban housing shortages. These compact, efficient homes offer property owners a flexible way to optimize their space. ADUs can serve as additional living quarters for multigenerational families, a source of rental income, or even a comfortable space for guests. They are also ideal for use as a home office, studio, or hobby space, particularly for those who need more room than the main house provides. This versatility not only enhances the value of the property but also helps increase housing options within the community, addressing broader housing needs.
How many ADUs Can I Build?
In California, ADUs can be built on residentially zoned lots, whether single-family or multifamily, as long as there is an existing primary dwelling unit on the property.
Single-family properties are allowed to add both an ADU and a Junior ADU (JADU). Multifamily properties can add as many ADUs as there are existing units on the property, up to a maximum of eight starting in 2025 (thanks to SB 1211). Additionally, multifamily properties can convert non-habitable spaces, such as garages or storage areas, into ADUs. In the City of Los Angeles, even more ADUs may be possible through the ADU Bonus Program, allowing for further expansion of housing options.
What types of accessory dwelling units are there and where can you add ADUs?
ADUs offer a range of design and construction options, providing homeowners with flexibility to meet their specific needs. You can build a detached ADU, a stand-alone structure that offers completely independent living space on your property. Alternatively, an ADU can be attached to your existing home, functioning as an addition or expansion. Another option is to convert existing spaces, such as a garage, into a fully functional living area. These versatile choices allow homeowners to select the type of ADU that fits best with their property layout. Keep in mind that each jurisdiction has its own regulations governing what can be built, so it’s important to check local city guidelines here.
Considering Attached vs. Detached ADUs
As you start the process of adding an accessory dwelling unit (ADU) to your property, it's important to think about how different ADU styles can influence your living space and lifestyle. Each option has its own advantages, whether you're looking for guest accommodations, rental income, or space for multi-generational living. Check out our guide for essential insights on the differences between attached and detached ADUs.
Check your City's ADU Regulations
While new statewide ADU laws have made it easier to add an ADU in Los Angeles, each municipality still has its own unique requirements. Properly scoping and preparing your ADU project with these regulations in mind can make the difference between a smooth, quick permit process and a lengthy, expensive experience with resubmittals and additional fees.
What are the new ADU laws in California?
Over the past few decades, California has passed several laws promoting ADUs as a housing solution, making it significantly easier to add accessory dwelling units.
These state laws set a baseline for local regulations, with some cities sticking to the minimum requirements, while others, like Los Angeles, have adopted even more ADU-friendly policies. Below are some key state-wide regulations, but be sure to review your local ADU ordinance for specific rules that apply to your property.
Size & Reduced Set Backs
There is no minimum lot size requirement for ADUs in California. Local municipalities are required to allow at least an 850 sq. ft. one-bedroom or a 1,000 sq. ft. two-bedroom ADU with only 4-foot side and rear setbacks, and many cities permit units up to 1,200 sq. ft. Additionally, an 800 sq. ft. ADU must be allowed “by right,” even if it encroaches on front setbacks or exceeds floor area ratio (FAR) limits.
Lower Permitting Fees
Many impact and development fees for ADUs have been waived, and certain remaining fees can be reduced by understanding key square footage thresholds that trigger higher fees (e.g., 500 sq. ft., 750 sq. ft., 1,000 sq. ft.). Additionally, some cities offer further fee waivers to support ADU development.
No Owner Occupancy
Owner occupancy requirements for ADUs have been removed, allowing you to add ADUs on rental properties. Recent state regulations have permanently eliminated the need for owner occupancy, making it easier to develop ADUs.
HOAs
HOAs (Homeowners Associations) and CC&Rs (Covenants, Conditions & Restrictions) cannot impose unreasonable restrictions on ADU development. We design ADU exteriors to seamlessly blend with the main home, ensuring they meet the required standards for exterior finishes.
Parking
Most parking requirements have been eliminated, with no parking needed if the ADU is within 1/2 mile of public transit or car share services. If parking is required, it can often be easily addressed by designating spaces on the driveway.
Application Review
Building departments are required to respond to ADU applications within 60 days, and many act even sooner. However, this doesn’t guarantee quick approval, as the overall permitting process typically takes between 2 to 8 months.
How much does an ADU in Los Angeles or Ventura County Cost?
We’re happy you asked! We believe in full transparency and are eager to dive into the numbers with you. Visit our ADU Costs page through the link below to get all the details on the complete costs for designing, permitting, and building an ADU in Los Angeles.
How long does it take to build an ADU?
The full process of designing, permitting, and building a new construction ADU typically takes 5-12 months, depending on the complexity of your design, your location, and site conditions. The design phase generally takes 1-2 months, permitting and plan check lasts 2-8 months, and the build-out takes 3-5 months (varying based on jurisdiction and unit size). Learn more about each phase and the timelines involved.
Attached ADU
You can opt to expand your main home by adding an attached ADU, seamlessly integrating it with the existing structure. However, this option can bring some added complexity, as construction will need to account for the current building's layout and condition.
Detached ADU
Add a detached ADU to create additional living space that is completely separate from your main home. Keep in mind that each city has specific regulations regarding setbacks, which dictate how far the ADU must be from property lines and the existing residence. Be sure to check local requirements to ensure compliance.
Conversion
Another option is to convert an existing structure, such as a garage or other building on your property, into an ADU. This approach repurposes the space to create independent living quarters, which may either be attached to or separate from the main home, offering a practical and efficient way to maximize your property's potential.