An ADU (accessory dwelling unit) is a self-contained second home on your property, and in Los Angeles it typically costs $120,000 to $150,000 for a garage conversion or $150,000 to $400,000 for a detached new build in 2026. California now allows detached ADUs up to 1,200 square feet, and units of 750 square feet or less skip city impact fees. Here’s how ADUs work in LA, what they cost, and the rules you need to know.
So, you’ve heard about ADUs in Los Angeles, eh? Maybe a friend was talking about her ‘granny flat’ or ‘casita’, you saw your neighbor recently did a garage conversion, or perhaps you overheard your coworkers talking about their latest investment opportunity. Well, thanks to some updated regulations in California, many homeowners can now legally create an ADU Los Angeles – accessory dwelling units on their property.
Here at GreatBuildz, a free service that connects homeowners in Los Angeles, Orange County, Ventura & San Diego with reliable general contractors, we get inquiries every day about ADU projects – here are some key points you need to know.
The term ADU, otherwise known as an Accessory Dwelling Unit or Additional Dwelling Unit, is defined as a secondary housing unit with independent living facilities, on a residential lot in addition to the main house.
Recently, both in California and in Los Angeles, these ‘dwelling units’ have been getting a lot of attention as both the city and state have drastically relaxed the restrictions and rules around building ADUs. This has created a boom of interest by homeowners around building such ADU units in their backyard or converting their garage into a living space.
Key Takeaways
- Recent changes in California regulations, particularly in Los Angeles, have significantly eased the process for homeowners to legally construct Accessory Dwelling Units (ADUs) on their properties.
- Los Angeles ADU ordinances permit ADUs on most residentially zoned lots, regardless of size, and extend to multifamily properties, offering the potential for multiple ADUs on a single property.
- The cost of ADUs varies, with garage conversions typically ranging from $120,000 to $150,000 and new constructions from $150,000 to $400,000. Homeowners are exploring pre-fab ADUs, considering associated costs and benefits.
- Selecting a qualified contractor is essential for a successful ADU project. Homeowners are advised to choose licensed General Contractors with experience in ADU projects, considering factors such as licenses, insurance, references, and online reviews.
What you need to know about Los Angeles ADUs: There’s a New Law In Town
Let’s briefly discuss the guidelines which have recently changed to make accessory dwelling units much more viable for many homeowners. As one method to help assuage the housing crisis, the state, along with many California cities, has eased many previous restrictions to building these structures.
To simplify this article, I’ll be discussing the guidelines specific to Los Angeles ADU ordinance, so please keep in mind that other local cities will likely have their own set of rules. If you’d like to read about ADU regulations in other areas, see my articles on:
- Parking – Probably the most drastic change has been to the parking requirement. Whereas previously the city required off-street covered parking (garage, carport) for both the existing home and any new living structure proposed, the guideline now allows the main house parking to be uncovered (ie. the driveway) and ZERO parking for the additional ADU unit, as long as it’s near transit.
- Increase in maximum permitted size – in many cases you are allowed to build up to 1,200sf ADU, and the minimum max size all cities must allow in all cases is 800sf. Not sure how big to go? Here’s how to choose the right size ADU for your lot and budget.
- Greater variety of types of ADUs allowed – this includes garage conversions, stand alone ADUs, attached ADUs, detached ADUs, and in some cases two story ADUs
- Some impact fees are being waived to encourage homeowners to build – for more information, read this important memo from the LA Department of Building and Safety about ADUs
ADUs don’t require any ‘discretionary’ approval, meaning that you don’t need approvals from city planning dept, neighbors, planning boards, etc, as long as you meet the established guidelines. So, getting the right to build an accessory dwelling unit in Los Angeles is just a matter of submitting plans to the building department and going through the plancheck process to obtain an ADU permit.
Make sure to research the City of Los Angeles ADU ordinance for more information on the requirements and regulations of building an ADU.
Build a secondary suite for extra income.
Why build an Accessory Dwelling Unit on your property?
Many homeowners are excited about the simplified restrictions and are now exploring building an accessory dwelling unit on their property, but why? I’d say it comes down to two things: their new ability to add living space to their property in a simplified manner, coupled with the tremendous variety of potential uses for an ADU.
Adding square footage to an existing home in the past meant building an ‘addition’ or second story, which was a headache. It was often very costly and time-consuming, it usually required considerable changes to the existing layout of the home, and it meant living through the discomfort of construction in your home.
An accessory dwelling unit relieves many of these problems and allows for a ton of flexibility in uses. People are building them to use as extra space (an office or guest house), a music or yoga studio, a mancave or she-shed, or a home for their retired parents or grown children. One recent survey found that 61% of ADUs are built for multigenerational housing.
Beyond these ‘typical’ uses, it’s also an opportunity for a homeowner to use as a rental unit for additional income. I’ve heard from several soon-to-be retired homeowners planning to build an ADU in Los Angeles so they can move into it (as they don’t need as much space) and rent their primary home as a source of retirement income. That’s pretty ingenious.
What kind of ADUs are there?
The two primary options are either building a new ADU unit in the backyard or converting an existing garage to an ADU. A garage conversion is the most cost-effective option because the basic structure already exists. The downside is the limitation in size – most 2-car garages are only 300-400 square feet.
This is still enough space for a ‘studio’ or small one-bedroom unit, with both a kitchen and a bathroom. Alternatively, you could build an addition to your garage and convert the entire space to an ADU, which is a cost-effective way to create a larger ADU with 600-800sf and 2 bedrooms.
A new ADU, however, can take many forms.
It must be in the backyard or side yard area and not in front of the existing home. A new detached accessory unit is limited to 1,200 sf, while an addition attached to an existing home is limited to the lesser of either 1,200 sf or 50% of the size of the existing home.
A 400-600sf ADU is ideal for a one-bedroom floor plan and a 600-1,200 sf structure is enough to be one or two stories, with up to three bedrooms and multiple baths!
Note: An existing garage that is in front of the home may also be converted to an ADU. Or an existing attached garage can be converted to a Junior ADU.
What is a JADU (Junior ADU)?
A Junior Accessory Dwelling Unit (JADU) is a type of smaller, secondary dwelling unit that is typically created within the walls of an existing single-family home or inside the attached garage. A JADU is limited to a maximum size of 500 square feet. It is often created by converting a portion of the existing house, such as an attached garage or an unused room. A JADU must have an efficiency kitchen, which includes a cooking facility with appliances, a food preparation counter, and storage cabinet
It must have a separate entrance from the main living area to provide privacy and independence for the occupant. A JADU can share a bathroom with the main house or have its own separate bathroom. This choice now determines the occupancy rules. Until recently, every JADU required the property owner to live in either the main house or the JADU as their primary residence. A new law, AB 1154, changed that as of January 1, 2026: if the JADU has its own bathroom, there is no owner-occupancy requirement. Owners only need to live on the property when the JADU shares a bathroom with the main house. You can read more in our guide to the new 2026 ADU laws, including AB 1154.
Per the ADU regulations in California, almost any single family property may build both an ADU and a JADU if they choose.
Who can build an ADU?
The city of Los Angeles ADU ordinance has allowed ADUs on most residentially zoned lots regardless of their size as long as the structure meets the basic restrictions and there is an existing home already on the property (with only minor exceptions), meaning most LA homeowners have an opportunity to add an ADU on their property. With regard to parking, an ADU is exempt from any parking requirements as long as the property is within one-half mile of a public transit (bus stop, etc).
Los Angeles ADU’s are also allowed on multifamily properties such as duplex, triplex, four-plex, and apartment buildings. These properties generally have different guidelines for the construction of ADUs, but they also have the potential to build several ADU’s on a single property.
If converting an existing garage into an ADU, two spots need to be maintained for the existing residence but can be uncovered spots on a driveway, which can be side-by-side or even tandem. A new accessory dwelling unit must be at least 10’ away from the existing house and garage or it must be attached to either. Also, a new unit must be at least 4’ from both the rear and side property lines. A garage conversion into a living space, however, does NOT need to meet these setback requirements.
ADU’s are perfect for movies & sports.
How much does an ADU in Los Angeles cost?
Accessory dwelling unit costs can vary widely based on size, design, and construction type. One of the most affordable options is an ADU garage conversion, since the existing structure is already in place.
A garage conversion accessory dwelling unit typically includes adding interior walls, a kitchen, bathroom, windows, doors, plumbing, electrical, HVAC, insulation, and sewer connections. Most garage conversion ADUs cost between $120,000–$150,000, depending on finishes and homeowner goals. For a full breakdown by ADU type, see our guide to the cost to build an ADU in Los Angeles.
New construction accessory dwelling units generally range from $150,000–$400,000, with average costs around $300–$450 per square foot. Larger ADUs often have a lower cost per square foot, while two-story ADUs usually cost more due to additional structural work.
Accessory dwelling unit costs are also influenced by material selections, permitting fees, utility access, and exterior improvements like roofing, siding, landscaping, and hardscape.
How much does a pre-fab ADU cost?
Pre-fab or modular ADUs are getting a lot of attention recently. These homes are mostly constructed in a factory, shipped to your location, and assembled on-site. Quite a few new companies have popped up that manufacture these pre-fab ADUs, which often come in several floorplans and design options. Some are ultra-high-end and expensive while others are meant to be entry-level.
Pre-fab ADUs have some advantages and some disadvantages to traditional ADUs built onsite by general contractors. In terms of cost, they can initially seem cheaper than traditionally built ADUs, but it’s really important for consumers to include ALL the costs (not just the unit) such as taxes, shipping, craning, assembly, installation, permitting, utility connections, & foundations.
Use an ADU as a quiet, comfortable office.
How do I pay for an ADU?
Homeowners have multiple ways to finance their accessory dwelling unit project. Obviously, they can pay for it from their own savings. Or they can finance this construction by taking out a home equity line of credit, securing a construction loan, or using a home renovation loan which is often a very quick process, but comes with a higher interest rate, from a company like Lightstream or SoFi. There is also an interesting renovation loan program from a company called RenoFi, who will base your loan amount on the ‘post-construction’ value of your property, allowing you to borrow more than traditionally available.
There are quite a few financing options for ADUs now, so it just depends on your needs. This ADU financing blog provides the details on many top options for ADU financing.
Process and Timing
How long does it take to build an ADU?
As you can imagine, the timing is different for an ADU garage conversion versus a new construction project. For an ADU garage conversion, you can expect the entire process to take 5-6 months, which includes the time to design the architectural plans, wait for the city to conduct plancheck, and finally, the construction process – which will take about 2-3 months.
A new accessory dwelling unit will take longer for city plancheck and require a longer construction process, so you can expect the entire process to take 6-9 months, with the construction phase lasting 3-6 months.
Build a granny flat as a safe environment for aging parents.
If you already have an ‘unpermitted’ ADU or garage conversion, it’s currently a good time to get the appropriate ADU permits and construction completed to get this structure up to code and legalized. Once you complete this work, the city will issue you a Certificate of Occupancy for your ADU, which will make the space legal to rent and add value to your property upon sale.
The process will be similar to that above, but you’ll probably need to perform a lot less construction to legalize your ADU or garage conversion, so the timing will be shorter. Check out our full blog about legalizing a garage conversion or ADU.
What is the process of building an ADU?
The ADU typically begins with meeting experienced contractors to discuss your property, project goals, design ideas, size, site constraints, and estimated ADU costs. Once the vision is established, an architect or designer prepares the ADU plans.
After the plans are approved, contractors provide detailed bids and pricing. The homeowner then selects a contractor, signs a construction agreement, and submits the plans for city review and permitting. Once permits are approved, construction on the accessory dwelling unit can begin.
Homeowners should also update their insurance coverage to include the new ADU or garage conversion.
If your property is part of an HOA, review all HOA design guidelines and requirements before starting your accessory dwelling unit project. Under California law AB 670, HOAs cannot prohibit ADUs, but they can enforce architectural standards and community design rules. Understanding these requirements early can help streamline approvals and avoid delays during the planning process.
Common Mistakes to Avoid
Handling the construction of an ADU can be complex, and avoiding common mistakes is important for a successful project. Some frequent missteps include:
- Neglecting to thoroughly research local regulations: Ignoring zoning laws, permit requirements, or overlooking recent ordinance changes can lead to costly delays or even legal issues.
- Underestimating the overall costs: Homeowners might overlook expenses like utility connections, landscaping, or permit fees, resulting in budgetary overruns. A full financial plan that includes all potential costs is essential.
- Poor planning and design decisions: Failing to consider the ADU’s purpose, local market demands, or the existing property layout may lead to an impractical or poorly used space. Engaging an experienced architect or designer can help optimize the ADU’s functionality.
- Inadequate communication with neighbors: Keeping neighbors informed about the construction process, potential disruptions, and addressing their concerns proactively can prevent conflicts and foster community goodwill.
- Choosing an inexperienced or unlicensed contractor: Quality construction and adherence to local building codes are imperative. Thoroughly vetting contractors, checking references, and ensuring proper licensing and insurance are in place mitigate this risk.
Finding The Right Team – How do I hire a good Los Angeles ADU contractor?
When looking to build an accessory dwelling unit or even starting to explore the idea, it’s best to search for only local, licensed General Contractors. No other contractors are qualified or equipped to do this sort of construction, and using an unlicensed contractor or handyman would be a mistake.
Any contractors you contact, always confirm they have experience with these types of projects. It is best to hire a contractor who’s built additions and garage conversions in the past and knows the potential issues/pitfalls. There are several other important criteria you should use in selecting a contractor, not including their cost estimate.
How about your own ADU gym?
Other things to look for in a contractor include:
- Check for a valid contractor’s license: It’s extremely important to check their license on the Contractors State License Board website to confirm it is active, there are no disciplinary actions, and it has Workers Compensation insurance associated with it (assuming the GC has employees).
- Make sure they’re insured: Always ask the contractor for a copy of his insurance certificate and make sure that it hasn’t expired. It might be a good idea to call the insurer directly, just to be sure. There have been cases reported where uninsured contractors have ‘Photoshopped’ their insurance papers to trick homeowners, so you can never be too careful.
- Check their references: Ask your contractor for at least three references you can call. It’s important to ask them about their experience and satisfaction with the quality of the contractor’s work. If you can get any pictures of the work, even better.
- Read their reviews online: It’s also a good idea to do a Google & Social Media search of the contractor to ensure there are no major red flags. Read any reviews you can find about their business, and don’t be afraid to address what you found with the contractor if there is anything concerning.
Building an ADU is not dissimilar to building a small home. Therefore, it’s super important to interview multiple ADU contractors in Los Angeles.You can be certain there will be cost overruns and delays, so ensuring that you’ve hired an honest and trustworthy ADU contractor will make a big difference during the process. The right contractor will be upfront and communicative with you.
At GreatBuildz, we screen all contractors upfront using our ten-point vetting process. We suggest everyone else take these steps to building an ADU before hiring an ADU contractor. I’ve written a longer article on the topic of hiring an ADU contractor. If you’re currently in the process, take a look at the rest here: Ten Tips For Finding an ADU Contractor
Additional Considerations:
Here are a few other things to consider when building an ADU:
- Storage: ADUs are generally small and often don’t include a garage, so it’s important to include areas for the storage of various belongings. Storage areas can include built-in cabinets, closets, attics, or even outdoor sheds, etc.
- Laundry: Since an ADU is a full living unit, including laundry machines is a pretty important component. It’s not ideal to have the ADU share laundry with the main home or have to use a laundromat.
- HVAC: You’ll want to include an effective dual heating & air-conditioning system in your ADU, so you are comfortable year round in the unit.
- Kitchen island: It’s hard to squeeze in a kitchen island, but it’s a huge bonus if you can make space for it in the kitchen. Even a small island makes a kitchen more usable and elegant. Also, it’s very practical as it can be used as both a kitchen prep area as well as an eating table.
- Outdoor area & patio: It’s important to consider creating an outdoor private space for the ADU, as long as it’s a usable area. Creating a concrete patio or installing pavers makes for a good surface for some seating, etc. A few potted plants and flowers are a nice touch, and a lawn is unnecessary. Adding a patio cover is a very nice detail to create shade, but it may not be cheap.
- Privacy: It’s a good idea to create some privacy between the main house and your ADU by constructing fencing or a wall between the two. Ideally, you’ll also want to build a separate gate that can be used solely by the ADU occupant for their access.
- Natural light: ADUs are small and a good way to make them feel bigger is to ensure lots of natural light is available to the unit. This can be achieved with many windows, skylights, or glass patio doors.
- Solar: If you decide to build a new detached ADU in your backyard, you will now be required to add solar on the roof. This may add additional time to your construction schedule. Ask your contractor to plan ahead for the solar installation, and include the costs in your total estimate. If you are doing solar, you might consider making your ADU all electric (no gas) to take advantage of this…so you’d make sure to install an electric range, electric water heater and electric furnace.
- Soundproofing: Especially in the case of attached ADUs, you’ll want to make sure there is appropriate separation, insulation, and/or soundproofing material between each unit/home so that the occupants aren’t hearing noise coming from next door.
- Storage: There are many ways to make an ADU more comfortable for your tenant. One way is to incorporate ottomans as they are a great place to rest your feet and also store things. In addition, fold-down tables are great as they also conserve space but can be useful for many different purposes. Another thing to keep in mind is to use pocket doors, as they can divide rooms without there actually being a room while also conserving space. Cabinets and hangers are also good to implement inside the ADU for extra storage space as well. Tankless water heaters are commonly used in ADUs to help save money and space. Futons and daybeds can be dual-purpose and further conserve space. Using hooks in kitchens and bathrooms is a good way to conserve more space. Storing things under beds conserves space.
Frequently Asked Questions About ADUs in Los Angeles
How much does it cost to build an ADU in Los Angeles?
In Los Angeles, a garage-conversion ADU typically costs $120,000 to $150,000, and a detached new-construction ADU runs $150,000 to $400,000, or roughly $300 to $450 per square foot, in 2026. The final price depends on the size, the finishes, and your site conditions.
How big can an ADU be in California?
California allows detached ADUs up to 1,200 square feet, and cities cannot set a lower maximum. A junior ADU (JADU) is capped at 500 square feet and is usually created by converting space inside the existing home.
How long does it take to get an ADU approved in Los Angeles?
Under California law, the city must approve or deny a complete ADU application within 60 days. Building the ADU itself usually takes several more months, so plan for the full process from design to a finished unit.
Are there fees to build an ADU?
ADUs of 750 square feet or less are exempt from city impact fees under current California law, which lowers the total cost. You will still pay for plans, permits, and construction, and permit and city fees commonly run $5,000 to $20,000.
When it comes to finding the best ADU and garage conversion contractor in Los Angeles, Orange County, Ventura, or San Diego – GreatBuildz is simplifying the contractor search. GreatBuildz is a free service that connects homeowners with reliable, thoroughly screened general contractors and provides project support from start to finish.
Call now (818.317.3567) to chat with a real person about your next renovation project or visit our website for more information: www.greatbuildz.com
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