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Is it legal to convert my garage into an ADU?
Yes, if you own a single-family home anywhere in California with residential zoning you can build a Garage Conversion ADU. Each city and county have slightly different requirements for converting your garage into an ADU. Still, thanks to laws passed by the State of California, as of January 2017, every California homeowner can convert their attached or detached garage into a livable, rentable dwelling unit.
What is a Garage Conversion ADU?
Los Angeles City Ordinance No. 186481 dictates what an ADU is and where you can build one. The definition of an ADU as described by the City of LA states,
Los Angeles City Ordinance No. 186481
ACCESSORY DWELLING UNIT (ADU). An attached or detached residential dwelling unit provides complete independent living facilities for one or more persons and is located on a lot with a proposed or existing primary residence. It shall include permanent provisions for living, sleeping, eating, cooking, and sanitation on the same lot as the single-family or multifamily dwelling is or will be situated. ADUs include efficiency units as defined in Section 17958.1 of the Health and Safety Code, manufactured homes as defined in Section 18007 of the Health and Safety Code, and Movable Tiny Houses.
Should I convert my garage?
This is not a simple yes or no question. Whether or not you should convert your garage into a rental depends on many factors, and all homeowners will have their unique motivation for considering a garage conversion. When building a rental unit, guest home, or home office, you must thoughtfully weigh the pros and cons to decide which ADU type is best for you, your property, and your lifestyle.
Garage Conversion vs. New Construction ADU
Many homeowners consider the advantages and disadvantages of converting their garage vs. building a new ADU somewhere else on their property. There are two main advantages for converting a garage vs. building a new stand-alone ADU.
Garage Conversion Advantages
Construction Cost
The price for a garage conversion ADU is substantially less expensive than a new detached or attached ADU. Since the garage already exists, a conversion saves money on the foundation, framing, and roofing portions of the construction project.
Time Savings
A garage conversion is typically quicker to permit, and the construction timeline is much faster than building a new unit from scratch.
But in addition to the advantages, there are also disadvantages that you must consider.
Disadvantages of Converting Your Garage
Loss of garage space for parking
You are not required to replace the parking you lose when you convert your garage. But, when the garage conversion is complete, you will have less covered parking on your property or less storage if you do not park cars in your garage. This lack of parking and storage could be a turn-off for potential buyers.
Lower Return on Investment (ROI) vs New Construction
When you convert your garage to an ADU, you increase the property value in most instances because you add habitable square footage to the overall property. And since single-family homes are appraised based on the home's characteristics and the useable square footage, the ADU will increase the property's value.
But the other side of the coin is that you are converting your garage, which is a valuable amenity in California. A loss of a standard two-car garage will most likely decrease your home's value, offsetting some of the property value increase you gain with the new ADU's addition.
You will need to evaluate whether your garage's loss is a big deal and how it might affect your property's desirability for a future owner.
How much does it cost to convert my garage into an ADU?
Most standard 2-car garage conversions cost between $125,000 and $175,000. The size of the garage conversion, the location and access of the existing utilities, and the quality of the finish materials will influence the final price.
As examples, we can look at three different garage conversion projects and the approximate cost of each.
Exterior photo of a completed attached garage conversion project in Manhattan Beach.
Straight Garage Conversion (Modest and Simple)
Estimated budget $125,000 - $150,000
The fastest and least expensive garage conversion type is to leave the existing garage structure 100% intact. This means no additional square footage added and no changes to the overall structure of the garage.
In this scenario, you would add an efficiency kitchen, small ¾ bathroom, and mini-split HVAC system for heating and cooling. Additionally, building finish materials would be modest and simple (i.e., No designer plumbing fixtures or fancy kitchen cabinets and countertops).
A project like this will end with a nice, clean ADU that will be safe and livable but without any bells and whistles of a more expensive conversion.
High-End Garage Conversion (Structural and Architectural Upgrades)
Estimated budget $150,000 - $200,000
You may find that a straight garage conversion is not exactly what you need. Maybe your garage is old and needs structural upgrades. Or perhaps you want to create vaulted/lofted ceilings or a small addition to make the ADU feel larger.
In this scenario, the ADU would have a larger kitchen and a full bathroom. The electrical and gas services will be individually metered so that the ADU will be billed separately for utilities. And your contractor will alter the roof structure to create a lofted/vaulted ceiling.
A project with this budget will feel like a small custom home, and the interiors will feel larger and more luxurious. A separate bedroom area adds privacy to the conversion.
High-End Garage Conversion + Small Addition project we designed in Los Angeles.
Exterior photo of a 3-Car Garage Turned One-Bedroom garage conversion project.
3-Car Garage Conversion (Expanded Layouts)
Estimated budget $175,000+
Converting a 3-car garage into an ADU offers significantly more flexibility but also introduces added complexity. These projects often require new foundation work, upgraded framing, and extensive reconfiguration of walls to meet current structural and energy codes.
The larger footprint allows for a true one-bedroom or even two-bedroom ADU layout, complete with a full-size kitchen, laundry area, and spacious living zone. It's an ideal option for homeowners looking to create a long-term rental, guest suite, or multigenerational living space with added comfort and privacy.
While the construction cost is higher due to the increased square footage and required upgrades, the value added to the property is substantial. A well-designed 3-car garage conversion can rival the look, feel, and functionality of a newly built detached ADU — without the need to start from scratch.
2-Story ADU Garage Conversion (Full Custom Rebuild)
Estimated budget $300,000+
The next and final level of ADU garage conversion is the fully custom rebuild. The project will include the demolition of the existing garage to create space for a new 2-story ADU.
In this scenario, the owner can choose a custom floorplan to match their lifestyle. The new ADU will retain no evidence that it was ever built initially as a garage. The ADU will feature luxury finishes to match any taste and can include multiple living and sleeping areas.
A project like this will add substantially more value to the property than it will cost to build and is a perfect option for homeowners wanting to create a beautiful home office or guest suite on their property.
Photo above shows a Full Rebuild and 2nd Story Garage Conversion Addition project we designed in Los Angeles.
How long does it take to convert my garage?
The garage conversion timeline will depend on the scope of work. For a modest, straight-forward conversion, the planning and permitting phase can take as little as six weeks, and the construction will last as little as 8-12 weeks.
For a larger ADU project, 3-6 months is more realistic for the planning and permitting phase, with another 5-6 months reserved for the construction phase.
From start to finish, including design, permitting, and construction, most garage conversions take approximately 9-12 months.
Is a Garage Conversion ADU a good investment?
Yes, in terms of Return on Investment (ROI), a garage conversion can be a great way to increase the value of your property. In most cases, the property value will increase by more than the cost to convert the garage.
But the benefits are not only financial. Imagine how much more productive you will be in a private office space. The relief you will feel knowing your aging loved ones have a safe and comfortable place to live. Or the fun you will have to host out-of-town guests in your private guest suite.
Sample Garage Conversion ADU Floorplans
Below are a few examples of what a garage conversion ADU can look like. Whether you elect to design and build a modest garage conversion, or decide a rebuild conversion is best for you, a good design and good plan is the first place to start.
2-Car Garage Conversion Plan
The plan below shows a straight garage conversion of an existing attached 2-car garage. This type of ADU is the least expensive to plan and build. This ADU floorplan offers a studio apartment conversion with a small kitchen, full-size bathroom, and large open living room/bedroom.
This ADU was designed and built by a family with two young children who wanted an apartment where grandma and grandpa could stay when visiting for long periods.
Garage Conversion Plan with Small Addition
The floorplan below shows a small addition to an existing 2-car detached garage.
We designed this ADU for a young couple that wanted to convert their garage into a rental apartment to help offset their mortgage payment and to help them move into their dream home a few years earlier than planned.
We added a small addition to make space for a one-bedroom ADU instead of a smaller studio ADU that would have been possible without the expansion. The one-bedroom ADU increased the rent they could charge for the unit with a slight increase in the overall design and construction cost.
2-Car Garage Conversion + Small Addition project in Santa Monica.
Sample 3-Car Garage ADU floor plan.
3-Car Garage ADU Floor Plan
The plan below shows a converted 3-car garage with the larger footprint reconfigured into a true one-bedroom layout. A separate bedroom, full bathroom, full kitchen, and dedicated living area replace what was once parking and storage.
This plan was developed for a family converting an oversized detached garage into independent living space for their adult son with special needs — providing him a real, private home a short walk from the main house.
The 3-car footprint is the sweet spot for a one-bedroom conversion. It is large enough for a comfortable layout without requiring an addition, and small enough to keep the construction cost well below a new-construction detached ADU at the same square footage.
Garage Conversion Rebuild with Second Story Addition
Sometimes your existing garage is not large enough to accommodate the size of ADU you need. In this scenario, a garage conversion rebuild could be the perfect answer as it allows you to double the amount of floor space within the existing garage's footprint.
The plan below was developed for a hard-working couple that found themselves both working from home. They needed space, so they rented their existing 2bd/1ba home on the property, and moved into the new 3bd/2ba ADU.
We designed a solution that had a nice open floorplan on the first floor, and the second floor contains 3 full-size bedrooms and 2 luxurious bathrooms.
Conclusion
A Garage Conversion ADU is a great way to add livable space to an existing property for a relatively low price. If you need additional living areas quickly or have an immediate need for housing or a rental apartment, a Garage Conversion ADU might be the perfect solution.
But remember that converting your garage means eliminating off-street covered parking, which is a valuable commodity in Los Angeles. If you decide to convert your garage, make sure you evaluate all your options, including detached and attached new construction ADUs as they might be good options as well.
