The short answer
A prefab ADU in Los Angeles is built in a factory and set on a foundation you pour on site. The unit itself is faster and the price is fixed, but roughly 40 percent of the total cost is still site work: foundation, utility trenching, crane access and final connections.
Typical cost in Los Angeles
From $115,000
Nest 200 sq ft $115k / Nest One 500 sq ft $263k / Nest Two 638 sq ft $317k
A prefab ADU in Los Angeles is built in a factory and set on a foundation you pour on site. The unit itself is faster and the price is fixed, but roughly 40 percent of the total cost is still site work: foundation, utility trenching, crane access and final connections. That is the part we handle in Los Angeles, and it is the part that decides whether a prefab actually saves you money on your lot.
Where prefab genuinely wins
- Flat lots with a clear crane path from the street to the back yard
- Standard sizes between 400 and 800 sq ft where the factory catalog fits
- Owners who need a firm delivery date more than they need custom design
- Second and third units on a lot, where the design is already proven
- Sites where a long site-built schedule would disrupt an existing tenant
Where prefab does not save money
- Hillside lots in Silver Lake, Echo Park or the Palisades where craning is impractical
- Narrow LA lots with no side access wide enough for a module
- Sloped sites needing caissons or a stepped foundation, which erases the savings
- Any design that deviates from the factory catalog
- Lots where a utility upgrade dominates the budget regardless of build method
Site work we perform
- Access study and crane path survey before you order the unit
- Engineered foundation designed to the manufacturer's anchor specification
- Water, sewer and electrical trenching from the main service to the pad
- Crane coordination, street permit and set-day traffic control
- Final utility connections, exterior finishes and LADBS final inspection
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 prefab / modular adu 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
Is a prefab ADU cheaper than site-built in Los Angeles?
Sometimes, by roughly 10 to 15 percent on a flat lot with easy crane access. On hillside or narrow LA lots the site work and craning costs erase the saving entirely, which is why the access study comes first.
How long does a prefab ADU take?
Ten to sixteen weeks of factory build running in parallel with your permit, then two to four weeks of site work after the set. Total is often three to four months faster than site-built.
Do prefab ADUs still need a permit?
Yes. The unit carries state HCD approval for its construction, but the site plan, foundation, setbacks and utility connections all go through LADBS plan check exactly like a site-built ADU.
Can a crane reach my back yard?
That is the first thing we check. It depends on street width, overhead power lines, tree canopy and the setback between houses. We run the access study before you place a factory order.
Does a prefab ADU appraise the same as site-built?
A modular unit built to state HCD standards appraises as permanent construction, the same as site-built. A manufactured or mobile unit on a chassis does not, and we do not install those.
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.