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How to Build an Accessory Dwelling Unit in Los Angeles, CA

ADU homes, or granny flats, help L.A. homeowners create more livable space

Backyard accessory dwelling unit ADU in Los Angles
New ADU by South Land Remodeling

In 2017, a new law made it easier for residents to build an accessory dwelling unit (ADU) on their Los Angeles property. Now, the number of people building these in-law suites (AKA a granny flat or mother-in-law house) has skyrocketed – and for good reason. Real estate in the City of Angels is generally quite expensive and limited in square footage. An ADU delivers much-needed bonus space as well as home equity.

If you’re in the market for an accessory dwelling unit, and you live in Los Angeles County, here’s what you need to know.

What is an ADU?

An ADU acts as a stand-alone home with its own kitchen, bath, bedroom and living space. It can be attached or detached from the existing residence, and can be built from scratch or as a garage conversion. As an ADU architect in Los Angeles, South Land Remodeling can construct your ADU, giving you extra living space that acts as a guest house, rental unit, separate living or workspace, gym or pool house. 

Does My Home Qualify for an ADU?

Again, the law passed in 2017 (see details below) makes this more possible than ever. The biggest consideration is you must own a single-family home. If so, you’ll need backyard space or garage large enough to build the structure you want. Because an ADU acts as a stand-alone home, you’ll also need space for an additional parking spot, or the home must be located a half mile from public transit. If all this applies to you, then you very well could build an ADU. For more specifics, check out this handy guidebook for building an ADU.

Will an ADU Fit on My Lot?

Every property is different, but the good news is there’s no minimum lot size requirement. The key metric here is the ADU cannot exceed 50% the square footage of the main house. For example, an ADU for a 2,000-square-foot home cannot exceed 1,000 square feet. For more information, check out this one-sheet on ADU development standards. We recommend speaking to a licensed ADU contractor, who can evaluate your lot’s potential and even come up with creative ways to build an ADU even when you think it might not be possible.

Do I Need an ADU Permit?

After your ADU architect draws plans for your addition, you’ll need to apply to the local government or Department of Regional Planning in the city of Los Angeles. They will review the plan and zoning to determine if your ADU is permittable. At South Land Remodeling, we handle this entire process for you, taking a big to-do off your honey-do list. If not working with us, we recommend finding an experienced architect or general contractor who can manage the permit process for you.

How Much Does an ADU Cost?

Just as every property is different, so is every ADU. The size of your granny flat, the finishes, the functionality, etc. all play into the overall cost. We always recommend talking to at least three ADU architects and/or general contractors to get cost estimates. That said, our ADU projects for garage conversions can average from $60,000-$90,000 and ADUs built from scratch average from $150,000-$350,000 – but contact us for an ADU inspection and exact quote.

California ADU Laws

“As of January 1, 2019, homeowners who created accessory dwelling units (ADUs) without the required building permits may have the opportunity to bring their ADUs into compliance. For ADUs that were constructed without building permits, local building officials now have the option to inspect an ADU and apply the building standards that were in effect at the time the unit was constructed. This bill: SB 1226 (Bates), adds Section 17958.12 to the California Health and Safety Code, and with application of appropriate building codes, may allow issuance of a building permit for the residential unit.

The Legislature further updated ADU law effective January 1, 2018, to clarify and improve various provisions in order to promote the development of ADUs. These include allowing ADUs to be built concurrently with a single-family home, opening areas where ADUs can be built to include all zoning districts that allow single-family uses, modifying fees from utilities, such as special districts and water corporations, and reducing parking requirements. Please see the HCD Technical Assistance Memorandum: Accessory Dwelling Unit Legislation (PDF), for more information.

State legislation that took effect January 1, 2017 gave California cities more flexibility and latitude for allowing homeowners to build ADUs. Three separate bills were introduced and signed by Governor Brown; SB 1069 (Wieckowski), AB 2299 (Bloom), and AB 2406 (Thurmond). Each of these land use bills make it easier than ever for homeowners to take advantage of this attractive opportunity.” For more information about ADU laws in California, visit"

Looking for an ADU architect and contractor? Call South Land Remodeling today for a free consult and quote!


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