Both are legal ADUs. The right one depends on your garage, your lot and what you want the space to do.
Short answer: a garage conversion is usually the faster and more affordable path, and a detached ADU gives you more space and more design freedom. Both are legal accessory dwelling units (ADUs) in California, and both need permits. Here is how to choose.
| Garage conversion | Detached ADU | |
|---|---|---|
| Structure | Uses the existing walls, slab and roof | New foundation, framing and roof |
| Cost direction | Usually lower, because the shell already exists | Usually higher, because it is a new building |
| Speed | Usually faster | Usually slower |
| Size | Limited by the size of the garage | More flexible, within local rules |
| Design freedom | Limited by the existing structure | High |
| Utilities | Often closer to existing connections | May need longer runs for power, water and sewer |
| Parking | You lose the garage space | Garage stays in place |
For real numbers, see our ADU cost guide, which lists ranges by ADU type.
If your garage is in good shape and the size works for you, converting it is usually the smartest first move. You use what you already have, the project moves faster, and most conversions fit a studio or a one bedroom. We check the slab, the structure and the utilities on a site visit so there are no surprises in the price.
In many cases the city cannot require you to replace the parking you lose when you convert a garage. Rules vary by city and by property, so we confirm the rule for your address before you commit.
Both types need building permits. We prepare the plans, handle structural engineering and energy compliance, and submit everything to your city or county. Utilities matter too: we plan for power, plumbing, heating and cooling, insulation and egress so the space is legal and comfortable. Our permit guide explains what triggers a permit in California.
A junior ADU (JADU) is a smaller unit built inside your existing house. It can be the right answer when the lot is tight or the budget is small. We compare an ADU and a JADU for your lot on the first visit.
We have dedicated pages for garage conversions in Canoga Park, Sherman Oaks and Woodland Hills, and for ADU construction in Studio City, Burbank and Culver City. Our HGTV work with Tarek El Moussa included two new detached, side by side ADUs built from the ground up.
Not in the converted space. A conversion turns the garage into living space. If you want to keep parking, a detached or attached ADU may fit your goals better.
A garage conversion is usually faster because the structure, slab and roof already exist. Permit review still varies by city, and we give you a written schedule after the site visit.
Yes. A junior ADU (JADU) is a smaller unit built inside your existing house. We can compare an ADU and a JADU for your lot.
Ready to compare? See our garage conversion to ADU and ADU builders in Los Angeles pages.
Want a real number and schedule for your project? Schedule a discovery call →, or read our kitchen & bathroom remodel cost guide.
Tell us about your project and we'll set up a discovery call to talk it through. Serving LA and the Valley.