Want a number for your own ADU? Try the ADU cost estimator.
What owners declared on their permits
Every Los Angeles building permit lists a declared valuation: the estimated construction value of the work. For ADU permits issued in 2025, the median was $50,000 for garage conversions, $35,000 for junior ADUs, $65,000 for attached ADUs and $109,482 for detached ADUs.
| Type | Median declared value | Middle half | Permits |
|---|---|---|---|
| Garage conversion | $50,000 | $35,000 – $80,000 | 2,427 |
| Junior ADU (JADU) | $35,000 | $21,500 – $55,000 | 649 |
| Attached ADU | $65,000 | $30,000 – $150,000 | 758 |
| Detached ADU | $109,482 | $76,200 – $150,000 | 1,750 |
Why the real cost is usually higher
Declared values are estimates made at permit time, and they tend to understate what owners end up paying. They often leave out design and engineering, permit and impact fees, utility connections, site work, and finishes or appliances chosen later. Treat them as a floor for comparing projects, not a budget. The only way to a real number is written quotes from licensed builders for your lot.
How values have changed
| Median declared value | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Garage conversion | $30,000 | $40,000 | $50,000 | $50,000 | $50,000 | $50,000 |
| Junior ADU (JADU) | $20,000 | $25,000 | $35,000 | $30,000 | $30,000 | $35,000 |
| Attached ADU | $26,500 | $35,000 | $45,000 | $50,000 | $60,000 | $65,000 |
| Detached ADU | $98,000 | $100,000 | $100,394 | $110,000 | $100,000 | $109,482 |
By neighborhood
For detached ADUs in the San Fernando Valley's Los Angeles neighborhoods (2020 to date), the highest median declared values were in Van Nuys ($120,000), Sylmar ($120,000) and Sun Valley ($120,000); the lowest were in Toluca Lake ($78,000), Sherman Oaks ($85,000) and Studio City ($85,000).
Other cities
The annual reports other cities file with the state don't include declared values, so this site shows costs for Los Angeles only. Ask builders who work in your city for recent, comparable projects.
Getting a real number
- Get at least three written quotes for the same scope of work.
- Ask each builder for addresses of ADUs they have finished nearby, then look them up on our map to see the permits.
- Ask what the quote leaves out: design, engineering, fees, utility upgrades and site work.
- Read our guide to choosing a builder.
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