Short answer. In 2026, expect $250,000 to $450,000 for a detached ADU, $130,000 to $220,000 for a garage conversion, and $400 to $650 per square foot fully built and permitted. Final price depends on size, finishes, site access, utility separations, and city school fees. The breakdown below shows where every dollar goes.
Los Angeles is one of the most active ADU markets in the country. State law and city updates have removed most of the old roadblocks, which is why every other homeowner in Woodland Hills, Studio City, and Sherman Oaks has either started an ADU or is pricing one. The challenge is that the cost range published online is too wide to be useful. This guide narrows it down with real numbers from projects we have built and quoted in the last 18 months.
ADU cost in Los Angeles by type
Four ADU types, four very different cost profiles.
| ADU type | Typical size | 2026 cost range | Cost per sq ft |
|---|---|---|---|
| Detached new construction | 500 to 1,200 sq ft | $250,000 to $450,000+ | $400 to $650 |
| Attached addition to main home | 400 to 800 sq ft | $180,000 to $350,000 | $380 to $550 |
| Garage conversion | 350 to 480 sq ft | $130,000 to $220,000 | $300 to $450 |
| JADU within existing home | Up to 500 sq ft | $70,000 to $140,000 | $200 to $350 |
ADU cost in Los Angeles by size
Three of the most common detached ADU footprints we build.
| Size | Layout | 2026 cost range |
|---|---|---|
| 500 sq ft | Studio, full kitchen, full bath | $200,000 to $320,000 |
| 750 sq ft | 1 bedroom, 1 bath, kitchen, living room | $300,000 to $420,000 |
| 1,000 sq ft | 2 bedroom, 1 bath, full kitchen, living room | $400,000 to $550,000 |
Where the money actually goes
Here is the line item breakdown on a typical 750 sq ft detached ADU at the middle of the price range, fully permitted and built in the San Fernando Valley.
| Line item | Typical share of budget | Notes |
|---|---|---|
| Design, structural, MEP engineering | 7 to 10 percent | Architect or design build firm fees, soils report when needed |
| Permits, plan check, school fees | 4 to 8 percent | LADBS plan check, building permit, electrical permit, plumbing permit, school district fees over 500 sq ft |
| Site work, excavation, foundation | 10 to 15 percent | Slab on grade is most common, hillside lots can double this line |
| Framing, roof, exterior envelope | 20 to 25 percent | Lumber, sheathing, roofing, stucco or siding, windows, doors |
| Plumbing, electrical, HVAC rough | 14 to 18 percent | Includes sewer connection or lateral, panel work, mini split or central air |
| Interior finishes | 20 to 28 percent | Cabinets, countertops, flooring, tile, paint, fixtures, appliances |
| Final connections, inspections, punch | 3 to 5 percent | Utility sign-off, final inspections, walkthrough, certificate of occupancy |
What drives the cost up or down
These are the factors that move price the most on every ADU project we estimate.
- Site access. A backyard with only a 30-inch side gate doubles labor for material delivery and concrete pour.
- Utility separations. Pulling new electrical service from the street can add $8,000 to $25,000. Sewer separations are the second biggest variable.
- Soil and grade. Hillside lots in Woodland Hills, Studio City, and Calabasas often require engineered foundations, which can add $30,000 to $80,000.
- School district fees. Required when the ADU is over 500 sq ft. Currently around $5 to $7 per sq ft in most LA County school districts.
- Finish level. Stock cabinets and porcelain tile keep you near the bottom of the range. Custom cabinets, natural stone, and high-end appliances push toward the top.
What state and city rules let you do in 2026
California ADU law under Government Code Section 65852.2 sets the baseline. Cities must allow at least one ADU and one JADU on every single-family lot. Setback minimums are 4 feet from rear and side property lines. Cities cannot require parking for ADUs within a half mile of public transit. Owner occupancy is not required for ADUs permitted before 2025 and rules have continued to relax for new projects. Always verify the latest with LADBS or your city building department before designing.
How to get an accurate ADU estimate
An honest ADU estimate needs three things at minimum.
- Site visit with measurements, utility check, and grade observation.
- Preliminary plans or sketches showing scope, size, and layout.
- Finish allowances with real numbers, not vague placeholders.
Online ADU calculators give you a rough range but they do not see your site. The difference between a flat backyard with side-by-side utilities and a sloped hillside with a tight side gate can be $50,000 to $100,000 on the same square footage.
Before you book any contractor, run the CSLB license lookup walkthrough and confirm the license, bond, and workers compensation status. Then open the ADU service page for our build process. For a written estimate on your property, book a free onsite visit on the contact page.
