If you're a Los Angeles homeowner thinking about building an ADU, the first question is almost always the same: what will it cost? The honest answer is that it depends. What follows are the ranges Los Angeles homeowners are quoted today, and the factors that move a project from one end of them to the other.
The Short Answer
In Los Angeles, a well-built, permitted ADU lands between $120,000 and $350,000. That is a wide range, so it is worth breaking down. Every figure here is general planning information drawn from prevailing Los Angeles market rates, not an estimate or a quote. Real pricing comes from a site-specific evaluation and a written agreement.
What Drives ADU Costs in Los Angeles
The type of ADU you build moves the number more than its size does.
Garage conversion ADUs run cheapest, $80,000 to $150,000. The structure already exists; you're adding insulation, electrical, plumbing, and finishes. Not every garage converts. Some need foundation work or structural reinforcement that erases the savings.
Detached new-construction ADUs are the most common type built in Los Angeles, and the easiest to price. At 400–600 square feet, a detached ADU runs $150,000 to $250,000 all-in. Add a second story or higher finishes and you pass $300,000.
Junior ADUs (JADUs), converted from interior space you already have, land between $60,000 and $120,000. They carry restrictions: 500 square feet maximum, and they share utility connections with the main house.
What's Included in Those Numbers
A complete ADU quote covers design, permits, construction, and finishes. It excludes furniture and landscaping restoration. Costs break down like this:
- Design and architecture: $8,000–$20,000
- Permits (LA City or LA County): $5,000–$15,000
- Foundation and framing: $25,000–$55,000
- MEP (mechanical, electrical, plumbing): $30,000–$60,000
- Finishes, fixtures, cabinetry: $25,000–$70,000
The Los Angeles Permit Process
The permitting timeline drives more of the final cost than most homeowners expect. In Los Angeles, ADU permit approvals can take 3 to 9 months depending on the jurisdiction and the complexity of the design. A design-build firm carries this for you: submission, city responses, revisions, final approval. You are not the one chasing paperwork.
LA has some of the most permissive ADU rules in California. AB 68 and AB 881, both signed in 2019, removed most of what made these units hard to approve: owner-occupancy requirements, minimum lot sizes, and the discretionary review that could stall an application for a year. SB 9, passed in 2021, is a different law covering lot splits and duplexes, and it is often confused with the ADU rules.
Is an ADU Worth the Investment?
For many west side homeowners the numbers work. Appraisals and rents vary by neighbourhood and by unit. Treat any figure you read, including these, as a starting point for a conversation with an appraiser and a property manager rather than a projection for your lot.
The key word is well-designed. An ADU with cheap finishes, poor light and an awkward layout will not command strong rent. The unit has to read as a real home, not a garage with a kitchen.
Next Steps
If you are considering an ADU, the first step is a site visit: an assessment of the lot, the constraints, and what you can build on it. We are glad to walk it with you.
VARENTO is a design-build firm with ADU design and construction as one of our core services, working across Orange County and Los Angeles. See our Orange County page for details.