How much does it cost to convert a garage to an ADU in LA?
Converting a garage into an ADU in Los Angeles costs $100,000 to $200,000 all-in, or roughly $250 to $400 per square foot. A single-car garage runs $80,000–$120,000, a two-car $100,000–$160,000, and a three-car $140,000–$200,000. It takes about 6 to 10 months start to finish. The single biggest cost driver is not the finishes — it is the condition of the existing garage. A solid, newer garage converts cheaply; an old one with a cracked slab and no real foundation gets partly rebuilt, and that is where the money goes.
The cost, by garage size
| Garage | Typical all-in cost |
|---|---|
| Single-car (~250 sq ft) | $80,000 – $120,000 |
| Two-car (~400 sq ft) | $100,000 – $160,000 |
| Three-car (~600 sq ft) | $140,000 – $200,000 |
| Per square foot | $250 – $400 |
These are typical 2026 Los Angeles market ranges, not a quote. Your number depends almost entirely on the condition of the existing structure.
Why the garage's condition is the whole ballgame
A garage was built to shelter a car, not to be lived in. Turning it into a legal dwelling means it has to meet the same code as a house. That is where a "cheap" conversion quietly becomes an expensive one.
The things that reliably drive the number up:
- The slab. Garage slabs are thin and often cracked or sloped to a drain. A living space needs a proper, level, moisture-sealed floor. Sometimes the slab is fine; sometimes it comes out.
- The foundation. Older garages sit on a shallow footing that will not carry code loads. Adding a real perimeter footing is common and not cheap.
- The electrical panel. A garage on a 100-amp house panel cannot also run a kitchen, heat pump, and its own circuits. Budget a 200-amp upgrade.
- Plumbing. There is no sink or toilet in a garage. Water and sewer have to be run from the house, sometimes across the whole lot.
- Insulation, egress, ventilation. Real walls, a code-compliant egress window or door, and mechanical ventilation.
A newer garage with a solid slab and footing can skip most of this and land near the bottom of the range. A 1940s garage with a cracked slab lands near the top — or gets demolished and rebuilt, which is a different project.
What you are actually paying for
Roughly: structural and slab work 20–30%, plumbing and electrical 15–20%, kitchen and bath 15–20%, insulation/drywall/finishes 20%, permits and design 10–15%. Labor threads through all of it.
Notice what is not the big line item: the finishes. People try to rescue a budget by picking cheaper flooring. The budget was never blown by the flooring. It was blown by the sewer line and the panel.
The costs people forget
Utility connections. Water, sewer, and a bigger electrical service. Together these can add $20,000–$50,000 and they are invisible until someone opens the panel and checks the sewer lateral.
Impact fees. ADUs under 750 sq ft are exempt from impact fees under state law — which is exactly why so many garage-conversion ADUs come in at 749 square feet. Most garages are under that anyway.
Site work. Drainage, a path, and fire access. Minor on a flat lot, real on a hillside.
How to not get surprised
Before you fall in love with a floor plan, have a licensed contractor do three things on site: look under the slab edge, open the electrical panel, and find the sewer lateral. Those three checks predict 80% of the cost surprises. A contractor who does them at the walkthrough is saving you money, even when the number comes back higher than you hoped.
Get the sequence right
Feasibility and site check → design → structural and Title 24 → plan check → permit → build → inspections → final. Jumping straight to "how much per square foot" is how people end up $40,000 over.
DN Builders Group Inc is a licensed, bonded general contractor based in Burbank (CA Lic. #1139710). See our home additions & ADUs page, our post on what an ADU costs in Los Angeles, or request a site walkthrough. Figures are typical 2026 Los Angeles market ranges, not a quote, and this is general information rather than legal or financial advice.
Questions
Is converting a garage cheaper than building a new detached ADU?
Yes, usually meaningfully cheaper — the slab, walls, and roof already exist, and that shell is a large share of new-build cost. A garage conversion typically runs $100,000–$200,000 versus $200,000–$350,000 for a comparable new detached unit. But "cheaper" is not "cheap." Most garages still need a new or repaired slab, real insulation, egress, a panel upgrade, and plumbing run from the house.
Do I lose my required parking if I convert the garage?
Under current California ADU law, cities generally cannot require you to replace the parking you remove when you convert a garage into an ADU. Los Angeles follows the state rule. This is one of the biggest reasons garage conversions exploded — you are not forced to rebuild a carport somewhere else on the lot. Confirm the current rule with your city, since local implementation varies.
How long does a garage conversion take in Los Angeles?
Plan on 6 to 10 months end to end — 1 to 2 months of design and engineering, 2 to 4 months for plan check and permits, and 3 to 5 months of construction. State law caps ADU permit review at 60 days once the application is complete, but "once complete" is the catch — an incomplete submittal restarts the clock.