Cost To Build an ADU in Los Angeles – Guide for 2024

ADUs (Accessory dwelling units) are a popular way for Los Angeles homeowners to add livable space to their property. Converting a garage or building a stand-alone ADU can add significant value. How much does it cost to build an ADU in LA? In this comprehensive guide, we’ll cover everything you need to know about the cost to build an ADU, budgeting, planning for your ADU project as well as finding a great ADU contractor.

Here at GreatBuildz, a free service that connects homeowners in Los Angeles, Orange County, Ventura, or San Diego with reliable ADU contractors, we speak to homeowners every day about the costs of building an ADU – here are some costs, considerations, ideas, and tips to get you started. Call us at 818.317.3567 to speak with an ADU expert.

How Much Does it Cost to Build an ADU in Los Angeles?

cost to build an ADU Los Angeles in black

The cost to build an ADU in Los Angeles is based on the size of the unit:

Cost to build Garage Conversion ADU                                   $95,000 – $125,000

Cost to build 400-500sf ADU                                                  $150,000 – $200,000

Cost to build 600-800sf ADU                                                  $200,000 – $250,000

Cost to build 800-1000sf ADU                                                $250,000 – $300,000

Cost to build 1000-1200sf ADU                                              $300,000 – $350,000

Cost to build 2-story ADU                                                       $350,000 – $400,000

ADU Building Costs Calculator in Los Angeles

Generally, you can estimate $300-$400 per square foot as a rough estimate for a new ADU in Los Angeles and Southern California. The wide range in price accounts for the differences in floorplan, materials, site conditions, and additional amenities between different ADUs. The absolute minimum price for a new ADU in Los Angeles and SoCal is about $250 per square foot (for a large unit – say 1200sf).

Keep in mind that additional improvements to your property will cost extra…things like landscaping, hardscape, concrete, fencing, etc. Also, don’t forget to budget for city plan check, ADU permit, and other city fees. You can expect these to average between $5,000 and $20,000.

Keep in mind that, recently, new building requirements have increased the total cost to build an ADU. These include things like the requirement to install interior fire-retarding sprinklers. Additionally, all new residential construction in California must include solar panels, so be prepared for this cost. And, there may be other requirements to use energy-efficient systems like heat pumps and tankless water heaters.

Costs for ADU Building Plans

The cost of getting the building plans for your specific ADU design in Los Angeles and SoCal ranges between $8,000 – $20,000. Because there are so many simple plan layouts available online, it might be enticing to think that you can just download a free set of plans. But that’s unfortunately wishful thinking. A basic size and floorplan are just a start when it comes to getting your ADU plans approved by the city building department.

You’re really paying an architect/designer to create a full plan set for your ADU that includes structural engineering, Title 24 energy requirements, construction details, and much more. You’re also paying them to submit these plans to the building department for plan check and make any corrections required. Finally, you pay them for their expertise and the liability/responsibility they are taking to certify these plans are safe and up to building codes.

Factors Impacting the Cost to Build an ADU in Los Angeles

Many variables influence the final price:

– Size – As I discussed above, the cost of an ADU goes up with size. However, please note that as an ADU goes up in size, the cost per square foot actually decreases. So a 1200sf ADU will cost less PER SQUARE FOOT than a 400sf ADU.

– Layout – More complex designs cost more. Keeping a simple rectangular shape is the most cost-effective design.

– Materials – Using higher-end or expensive materials will obviously increase costs

– Appliances/fixtures – Higher quality appliances and fixtures will add to the overall expense of the ADU

– Utilities – Most people see a home or ADU and only think about the cost of the structure itself. We often forget about what we don’t see…namely the utilities that have to serve the ADU. You’ll need to run new electrical, water, sewer (and maybe gas) lines to the ADU, all of which run underground.

Digging, installing, and connecting these utilities is not a small part of your entire ADU budget. And the price for these items in the budget will depend on the length of the installation and the challenge in accessing the connection point. If you have to run these lines under concrete, that will add costs to your budget.

– Site conditions – If your yard or site is flat, that makes things easy, but if you have any slopes, you’ll need to have an area graded flat and potentially add retaining walls. If you have trees that need removal, that can also add to costs. And one thing most people don’t consider is the ‘access’ to their backyard. If there is plenty of room to get machinery into the yard, that reduces the effort of the contractor. However, if the access is limited, much of the work (digging, etc) will have to be done by hand.

– Location – Some areas are just easier to work in. A property with plenty of room to park and work will create an easier and cheaper work environment for contractors. Alternatively, a location with limited parking, a steep street, or other limitations on access will make things difficult and more expensive.

ADU Design vs Cost Considerations

cost to build an ADU Los Angeles kitchen

Just like any home, an ADU can be designed to be simple and basic or ultra-luxurious and this will greatly factor into the final price. Let’s face it, an ADU is just a small version of a house and has the same elements…a kitchen, bathroom, bedroom, etc. So you can design for a small, simple kitchen with minimal appliances and basic, builder-grade cabinets and countertops. Alternatively, you can plan for a custom kitchen with an island and expensive appliances.

Your design will greatly affect your cost. Items like vaulted ceilings, expensive windows, exterior siding, and patio covers will obviously expand the budget of your ADU. If you’re looking to build a budget-friendly ADU, check out this blog about how to save costs on your ADU. Additionally, you’ll want to utilize cost-friendly materials such as laminate flooring, basic vinyl windows, stucco exterior, etc.

As I already mentioned above, if you’re building a large ADU (over 1000sf), you should be aware that two story is more expensive than one story. Of course, the tradeoff is that a single-story ADU will take up a larger ‘footprint’ and more of your exterior yard space.

Also, it should go without saying that a basic rectangular design will be cost-effective versus one with peculiar designs like curved walls. Some of the LA ‘pre-approved’ ADU plans that are available might be cheaper to utilize versus a custom design, but based on their design/layout, they sure look expensive to build!

ADU Sizes and Layouts

Garage conversion: an average garage conversion is about 350-400sf in size. This size can accommodate a small living area, kitchen, bathroom, and sleeping area…which translates to essentially a studio apartment. It would be quite tight to fit a one-bedroom unit in this size space.

400-600sf ADU: this size can generally accommodate a one-bedroom, one-bath unit with all the other amenities mentioned above.

600-800sf ADU: This size will accommodate a generous one-bedroom, one-bath unit. If you’re planning over 700sf, you should be able to fit a two-bedroom, one-bath configuration. But keep in mind your bedroom will be small with limited closet space.

800-1000sf ADU: At this size of ADU, you can definitely have two bedrooms and can decide between a single bathroom and two bathrooms. You should have room for storage, a laundry closet, and even a small kitchen island.

1000-1200sf ADU: Once you’re at the largest size ADU allowed, you can decide between a two or three-bedroom home with two full bathrooms. Because a single-story ADU of this size will take up a lot of room on your lot, you can consider going two stories, with the living areas on the first floor and the bedrooms on top. Keep in mind, that building two stories is generally more expensive (and you have to build stairs), so be prepared for a higher cost/price.

Ways to Reduce ADU Building Costs

Some tactics to lower your budget include:

– Get multiple bids – Compare pricing from several contractors. Keep in mind that the lowest bid isn’t always the best contractor, so use price as just one of your criteria for hiring.

– Use cost-efficient materials – As I discussed briefly above, using basic-grade materials will help you save costs. Try to find materials that will limit your use of tile, as this is expensive to install. Consider laminate flooring or luxury vinyl tile for a real-wood look without the cost.

– Optimize layout – Try to plan your ADU such that you only have one plumbing wall. This means that you might put the kitchen next to the bathroom. That way, the contractor only has to install plumbing in one wall rather than multiple locations.

– Go simple on finishes – Utilize materials that are cost-effective. Stucco for the exterior finish. Basic color paint for the interior finish. Pre-fabricated cabinets and countertops for the kitchen. And fiberglass tub surround and enclosure for your bathroom.

Financing Your ADU

There are several ways to finance your ADU project, including using your savings, taking out a HELOC from a bank, or securing renovation financing through a company like RenoFi. For a full guide of all your options for ADU financing, check out our ADU financing blog.

cost to build an ADU Los Angeles interior

Getting Cost Estimates for your ADU

The ideal method to get the most accurate bids for a specific ADU project is to provide ADU contractors with a full set of completed plans along with an ADU scope checklist and even a materials list. If a contractor has all of this information, they will be able to give you a very precise bid. With this level of information provided to all your potential contractors, you can be relatively certain that all their bids will be consistent (apples-to-apples).

Without this extent of information, the ADU contractor’s estimates will get more and more approximated. So, if you’re just at the beginning stages of ADU planning and you don’t have any blueprints yet, you will have to accept a ballpark cost number from a contractor. If you tell them the approx. size of ADU you want, they can likely just give you a price range based on their previous projects and experience.

Detached ADU versus Attached ADU costs

There are going to be some limited cost savings for doing an attached ADU compared to a detached ADU. The attached ADU proximity to your home and the utilities will likely reduce the costs of running these utilities. You will have a shorter run to connect to your gas main and your water main, as well as connecting to your sewer lateral. So, presumably less cost of digging trenches, materials, etc. In addition, proximity to your home may make the access easier and simpler for your contractor.

On the other hand, working adjacent to your home may create more disturbance to your family as the construction (noise, dust, etc) will be right next to your home. There may also be some additional costs to “tie in” to your existing home. Connecting your new walls, foundation, roof, etc. to your existing home will take more work/coordination than building a detached ADU in its own separate location.

Therefore, when deciding on a detached ADU versus an attached ADU, cost savings should not be the primary factor to consider. You’re likely to make this decision based on your specific property scenario and where you’re ADU fits best on your property.

Understanding Los Angeles ADU Regulations

ADU requirements regulate size, height, setbacks, design aesthetics, utility connectivity, and more based on zoning. You can get more specific Los Angeles ADU guidelines and restrictions at this LADBS page. In general, per California state law, every residential property has the potential to build an ADU of up to 800-1200sf, with very few restrictions. Even the zoning and the size of the lot doesn’t matter. And even an HOA cannot restrict the construction of an ADU within a planned community.

However, there are other restrictions that might be specific to your property and location. For example, properties in high fire zones and coastal areas will have restrictions that you need to be aware of. Additionally, some ADU will require the addition of parking on the property while others will not.

There are a few ways to fully understand your unique ADU situation. One is the research the exact regulations with Los Angeles or your specific city building department. Another one is to find and speak with a local designer/architect who has experience working with ADUs in your specific area.

Los Angeles ADU Permit Costs and Process

Once you’ve had an architect or designer complete your ADU plans, the next step is to submit these plans to the Los Angeles building department for plan check. Depending on the department’s backlog, this process will take between a few weeks and a few months. You can expect to pay a few thousand to the city for the plan check process.

Once the plan check process is completed and the plans are approved, the city will be ready to issue a permit to start the construction. At this point, you will be required to pay for the permit and for any other ‘impact’ fees the city levies on new construction (park fees, school fees, sewer fees, etc). Now you’ll be looking at approx.. $5,000-$15,000.

The price of the permit includes the cost of having a city building inspector come to your property at various stages of construction to check and sign off on the contractor’s work. This is extremely important to ensure the work being done is safe and up to code. Unless you’re a construction expert, you’ll have no other way to know if the construction is sub-par.

cost to build an ADU Los Angeles living room

ADU Contractors

Simply put, only one type of contractor has the licensing and experience to build an ADU. That is a general contractor with a B-license from the California State License Board. An ADU is really just a small version of a house, and only a licensed general contractor is qualified and permitted to build a major construction project like this.

Using an unlicensed contractor or a handyman for this type of project would be a big mistake. A general contractor has the right crew and sub-contractors to take on a project with a wide breadth of construction trades. Think about the fact that an ADU requires dozens of different skilled trades. For example, an ADU requires, concrete, framing, electrical, drywall, roof, stucco, finish carpentry, HVAC, plumbing, and the list goes on.

So, when you’re ready to get bids for your ADU project, make sure you find and thoroughly screen several quality, experienced general contractors for your project. To find a few good contractors, get recommendations from your friends/family. If you don’t get enough quality candidates, you can use a contractor screening & matching service like GreatBuildz.

When you’re screening your contractors, first make sure they are licensed with the CSLB and hold both General Liability and Worker’s Compensation insurance. Beyond that, you should consider doing a thorough screening similar to the 10-point vetting process we use at GreatBuildz to select the best contractors in Los Angeles and Southern California.

We’ve written tons of other articles about things to know when planning an ADU…please check out these other blogs:

Stick Built vs Pre-fab ADU

ADU for Rental Income

ADU for First-time Buyers

Best Uses for an ADU

ADU Cost Savings

ADU Financing


When it comes to planning and coordinating an ADU project, you shouldn’t have to go it alone – GreatBuildz can help simplify your renovation experience.


GreatBuildz is a free service that connects homeowners in Los Angeles, Orange County, Ventura, or San Diego with reliable, thoroughly screened ADU contractors and provides project support from start to finish.


Call now (818.317.3567) to chat with a real person about your ADU project or visit our website for more information:

Hi, we're Paul and Jon - Co-Founders of GreatBuildz. We believe everyone deserves to find a great contractor, have a stress-free renovation, and enjoy their beautiful new space. There are so many contractors out there and it's often hard to tell the good from the bad... until it's too late. We started our company to help simplify your contractor search and help you have a stress-free renovation experience. We're always available to help, no matter where you are in the process. Click here to learn more about our story.

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