ADUs
Garage Conversion ADUs: The Real Numbers for 2026
Why converting an existing garage is still the fastest path to a rentable ADU in Los Angeles — and where the hidden costs actually hide.
A detached garage conversion is the cheapest ADU most LA homeowners can build. The walls, roof, and foundation are already there. The permitting path is streamlined by state law. And on almost every lot, a garage conversion can be built without triggering the parking replacement rules that used to make these projects so hard.
What you are actually paying for
Structural retrofit of the existing slab and walls. New windows and a proper entry door. Full insulation, drywall, and interior finishes. A kitchen, a bathroom, and the mechanical, electrical, and plumbing systems to support them. A separate electrical subpanel. Sewer and water tie-in to the existing house lines.
For a 400 square-foot detached garage conversion in LA, a realistic 2026 turnkey number is $140,000 to $190,000 including permits and finishes.
Where the surprises live
Slab elevation. Most garage slabs are not level enough for a habitable space. A self-leveling overpour adds $3,000 to $6,000.
Sewer lateral capacity. Older LA sewer laterals are often clay and undersized. Upgrading a lateral to handle a second bathroom can add $4,000 to $12,000 depending on trench length and hardscape.
Panel capacity. Adding a mini-split, a range, and a water heater to a 100-amp main panel usually pushes it over. A 200-amp panel upgrade is $4,500 to $8,000 in most LA neighborhoods.
The return math
In most of LA, a legal, permitted, well-finished garage conversion ADU rents for $2,200 to $3,200 a month depending on neighborhood. On the numbers above, that is a 5 to 8 year payback — before you count the assessed-value bump to the property itself.