As of October 2026, published Los Angeles estimates put most garage conversions at roughly $100,000 to $200,000 and most new detached ADUs at about $300,000 to $450,000 or more. Design, engineering, permits and utility work can add to that. Your lot, the unit's size and your finishes set the final number.
What does each type of ADU cost in Los Angeles?
| ADU type | Published LA range, as of October 2026 | Why |
|---|---|---|
| Garage conversion | Under $100,000 (simple) to over $200,000 (complex); local project totals about $75,000 to $300,000 | Reuses an existing structure; condition of slab and framing decides the scope |
| Detached ADU | About $300,000 to $450,000 or more | All-new foundation, structure, roof and utility runs |
| Attached ADU | No reliable LA-specific range found | New construction, but shares a wall and some systems with the house |
| Junior ADU | No reliable LA-specific range found | Interior work within the existing home, up to 500 sq ft |
These are third-party ranges, not our prices. We give a fixed, written price after a site visit.
What costs come on top of construction?
- Design and engineering. Published estimates put this at about 10% to 15% of construction cost. Pre-approved city plans can reduce it.
- Permit and plan-check fees. These vary by city and project size; published estimates range from about $1,500 to $25,000 including impact fees where they apply.
- Utilities. Sewer, water and electrical connections, a possible panel or service upgrade, and trenching to the back of the lot. Long trench runs alone can add $15,000 to $30,000, according to published estimates.
- Site work. Demolition, grading, retaining walls or tree work, where needed.
- Solar. New detached ADUs generally must include solar under the California Energy Code.
Do small ADUs pay impact fees?
No. As of October 2026, California law exempts ADUs of 750 sq ft or less of interior livable space from impact fees. Larger ADUs can be charged in proportion to the size of the main home. Junior ADUs of 500 sq ft or less are also exempt. Keeping a unit at or under 750 sq ft can be a real saving.
Why do ADU quotes differ so much?
It depends on what each quote includes. Some cover construction only; others include design, engineering, permits, utility work and solar. When you compare, ask each builder to show:
- whether design, engineering and permit fees are included
- what utility work is included, and to which point on the lot
- the finish level for cabinets, flooring, fixtures and appliances
- allowances, and what happens if actual costs exceed them
- who pays for plan-check corrections
What makes an ADU in Los Angeles cost more or less?
- Size. More square feet cost more, though fixed costs like the kitchen and bathroom do not scale down on a small unit.
- Lot. Hillside lots, poor soils and tight access raise cost. Flat lots with easy backyard access lower it.
- Existing structure. A sound garage can save money; one that needs a new slab or framing saves less.
- Utilities. Distance to the sewer line and the capacity of your electrical service.
- Finishes. Builder-grade versus custom finishes can swing the total widely.
How do I get a real number for my property?
Send us your address through the free consultation form. We check your lot's rules first, visit the site, and then give you a fixed, written price. Also read garage conversion vs. new ADU and how much rent an ADU can make.
Sources, as of October 2026:
- Block Renovation, "Garage Conversion to ADU in Los Angeles" (August 2026) and "A Deep Dive Into ADU Construction Costs" (updated June 2026), for cost ranges and soft-cost estimates.
- California Department of Housing and Community Development, ADU Handbook, for impact fee and solar rules.