The short answer
An ADU above a garage keeps the parking and adds the apartment, which no other ADU type does. The existing garage almost never carries a second story as-is, so the honest version of this build is a new structure: garage below, dwelling above.
Typical cost in Los Angeles
$450 to $650 per sq ft
Typical 550 sq ft unit over a 2-car garage: $250,000 to $360,000 all-in
An ADU above the garage is the only configuration that adds a dwelling without losing a single parking space or a square foot of yard. The catch nobody mentions up front: an existing Los Angeles garage almost never has the foundation or framing to carry a second story, so the real project is usually demolish and rebuild as a two-story structure, garage below, apartment above. Priced that way from the start, it is an excellent build. Priced as an addition to the old garage, it is a change-order machine.
Why the existing garage rarely survives
- 1940s to 1970s LA garages sit on unreinforced perimeter footings
- A second story needs engineered footings, shear walls and holdowns the old shell lacks
- Retrofitting an old shell usually costs more than rebuilding it
- A rebuild also resets the structure's life and warranty clock
- The footprint and alley position are what you are really keeping
What the configuration gets you
- Parking retained, which matters on permit-parking streets
- Zero net yard loss, the apartment occupies air, not ground
- Alley-loaded lots get a fully separate tenant entrance up an exterior stair
- Sound separation from the main house is automatic
- Storage below, income above
Design points that decide rentability
- Exterior stair placement so the tenant never crosses your yard
- One-hour floor assembly between garage and dwelling, required and good acoustics
- Plumbing stacked on one wall dropping straight to the sewer lateral
- Dormers or a partial-width second floor to stay inside the height limit
- A small landing deck at the top of the stair, cheap and it leases units
Get a straight answer on your lot in 48 hours
Send the property address. We pull the parcel data, zoning, setbacks and any overlay, then tell you whether a adu above garage works on it, what size fits and roughly what it costs. No site visit needed and no obligation.
Free 48-hour lot check
One field that matters: the address.
Common questions
Can I build on top of my existing garage?
Usually not as-is. Most Los Angeles garages sit on footings that cannot carry a second story, so the project becomes a rebuild: new engineered structure with a garage bay below and the ADU above. We confirm with a foundation inspection before design.
How tall can a garage-with-ADU structure be?
It needs the 18-foot transit allowance or more in most cases, since a garage bay plus a dwelling level stacks past 16 feet. Within half a mile of transit, 18 feet plus roof-pitch matching is available by right in Los Angeles.
Do I keep my parking?
Yes, that is the point of this configuration. The garage bay below remains parking or storage, and no replacement parking issue ever arises.
Is this cheaper than a detached two-story ADU?
Similar per square foot. The garage bay is cheap space to build but earns no rent, so the cost per rentable square foot runs slightly higher than a pure dwelling.
Can the ADU entrance face the alley?
On alley-loaded lots, yes, and it should. A separate alley entrance up an exterior stair gives the tenant complete independence and keeps your yard private.
Related ADU types
Comparing options? A garage conversion is the cheapest path to a legal unit, a detached ADU earns the most, and the JADU stack can put both on one lot. Cost figures for every type are in the LA cost breakdown.
Areas we build in
Sherman Oaks / Van Nuys / Pasadena / Glendale / Burbank / Santa Monica / Long Beach / Torrance / North Hollywood / Studio City / Woodland Hills / Encino / Northridge / Culver City / Inglewood / Silver Lake and across Los Angeles County.