A garage conversion usually costs less and keeps the existing footprint and setbacks, but you are limited by the garage's size and condition. A new detached ADU costs more and takes more work, but you choose the size, layout and position. If your garage is structurally sound and big enough, converting it is often the better value.
How do they compare side by side?
| Garage conversion | New detached ADU | |
|---|---|---|
| Published LA cost, as of October 2026 | Roughly $100,000 to $200,000 for most; local project totals span about $75,000 to $300,000 | About $300,000 to $450,000 or more |
| Size | The garage footprint, plus up to 150 sq ft for ingress and egress | Cities must allow at least 850 sq ft (1,000 with more than one bedroom) |
| Setbacks | Can stay where the garage is | Up to 4 feet side and rear |
| Height | Limited to the existing structure | At least 16 feet; 18 feet near major transit |
| Replacement parking | Not required | Not required for a demolished garage; new parking only where the city can require it |
| Solar | Generally exempt | Generally required |
| Design freedom | Limited by existing walls and roof | Full |
Rules as of October 2026, summarized from the California HCD ADU Handbook. Cost ranges from published Los Angeles estimates, not our prices.
When does a garage conversion make the most sense?
- The garage has a sound foundation, framing and roof.
- It sits close to a property line, where a new building would need a 4-foot setback.
- You want the lowest construction scope and keep your yard.
- A studio or one-bedroom in the garage footprint is enough.
When is a new ADU the better choice?
- The garage needs a new slab, new framing or a new roof anyway.
- You want more space or a second bedroom than the footprint allows.
- You want the unit placed for privacy, light or yard layout.
- You want to keep the garage for storage or parking.
Can I tear down the garage and build new in its place?
Yes. As of October 2026, state law says an ADU rebuilt in the same footprint as an existing structure does not have to meet the 4-foot setback, and a city cannot require you to replace the garage parking you demolish. That can give you new construction quality on the garage's spot. Check the rules for your city first, because a rebuild is new construction for code purposes.
So which one costs less for my lot?
It depends on what the garage inspection finds. The deciding questions are:
- Is the slab level enough, with room for new plumbing lines?
- Can the framing and roof carry insulation and current code loads?
- How far is the garage from the sewer line and electrical panel?
- Is there unpermitted past work that has to be opened up?
If most answers are good, a conversion usually wins on cost. If several are bad, a new build can come close in price with fewer compromises. We answer these during the site visit and price both options when it is close.
Sources, as of October 2026:
- California Department of Housing and Community Development, ADU Handbook.
- Block Renovation, "Garage Conversion to ADU in Los Angeles" (August 2026) and "A Deep Dive Into ADU Construction Costs" (updated June 2026).