Livermore rewrote its accessory dwelling unit (ADU) rules in July 2025. For a lot with a single-family home, the new chapter lists up to three unit types where the old section allowed one ADU, and state law sets a floor under the city’s rules. Below: what you can build, how garage conversions work, and what permits, fees and taxes look like. Rules checked against the city code on September 30, 2026.
Key Takeaways
– A Livermore lot with a single-family home can have a conversion ADU, a detached or attached ADU and a junior ADU.
– Converting a garage doesn’t require replacing the lost parking.
– No impact fees apply to ADUs of 750 square feet or less.
– A pre-approved plan gets reviewed in 7 business days instead of 15.
What changed in Livermore’s ADU rules in 2025
On July 28, 2025, the City Council adopted Ordinance 2176, which repealed the Development Code’s former ADU section, 6.03.120, according to the council’s meeting record. The rules now live in Development Code Chapter 11.30, and they didn’t simply loosen. Some limits went up and some came down:
| Rule | Former section 6.03.120 | Chapter 11.30 |
|---|---|---|
| Units on a single-family lot | One ADU | A conversion ADU, a detached or attached ADU and a JADU |
| Detached ADU size | 50% of the home’s floor area or 1,200 sq ft, whichever is less | 850 sq ft (one bedroom or fewer); 1,000 sq ft (more than one) |
| Detached ADU height | 15 ft (single story) | 16 ft, plus 2 ft to match the roof pitch |
| Side and rear setbacks | At least 5 ft | At least 4 ft |
| Distance from other buildings | At least 3 ft from the main home | At least 5 ft from all structures, with exceptions |
Sources: former Development Code, Part 6 and Chapter 11.30, retrieved September 30, 2026.
The size change cuts both ways. On a larger home, the old cap could reach 1,200 square feet, so the new limit is smaller. On a smaller home, where half the floor area fell below 850 square feet, the new limit is bigger. Chapter 11.30 also says that where it conflicts with state ADU law, state law governs.
What can you build on a Livermore lot?
On a lot with an existing single-family home, Chapter 11.30 permits “one or all” of three things: one conversion ADU, one detached or attached ADU, and one junior ADU (JADU).
| Type | Size | Setbacks |
|---|---|---|
| Conversion ADU (inside an existing home or structure, such as a garage) | No size cap; up to 150 sq ft of expansion for entry and exit | None beyond existing, if they meet fire and safety codes |
| Detached ADU | 850 sq ft with one bedroom or fewer; 1,000 sq ft with more | At least 4 ft from side, rear and street-side lines |
| Attached ADU | Up to 50% of the home’s floor area, but never limited below 850 or 1,000 sq ft | At least 4 ft from side, rear and street-side lines |
| Junior ADU | Up to 500 sq ft, within the home | Inside the home |
Source: Livermore Development Code Chapter 11.30, retrieved September 30, 2026.
Parking depends on the type. A new attached or detached ADU needs one off-street space on top of the home’s required parking, unless one of the chapter’s exemptions applies. Those include an application that includes a conversion ADU or a JADU, and a site within a half-mile walk of public transit, including local bus stops and ACE train.
Can you convert your garage into an ADU in Livermore?
Yes. State law permits converting detached garages, sheds and other existing detached accessory structures into ADUs, according to the California Department of Housing and Community Development (HCD) ADU Handbook. Under Livermore’s chapter, a garage converted into an ADU is a conversion ADU, and that brings three advantages:
- No size cap. It can use the whole existing space, plus up to 150 square feet of expansion for entry and exit.
- No new setbacks, as long as the existing ones meet state and local fire and safety codes.
- No replacement parking. When a garage is converted to build an ADU or JADU, the city doesn’t require you to replace it.
Which kind of garage you have matters. HCD says a JADU must be created within the single-family home, and it isn’t allowed in a detached structure. So an attached garage, which counts as part of the home, can become a conversion ADU or a JADU. A detached garage can become a conversion ADU, but not a JADU.
Mony has been through this at his own home. He converted his garage into a studio, and he describes it as a learning project.
Do you have to live on the property?
For an ADU, no. Livermore’s code says “there are no owner-occupancy requirements for an ADU,” and state law bars cities from imposing one on an ADU on a single-family lot (Government Code section 66315).
JADUs are where state law overrides the city’s text. Chapter 11.30 still says owner-occupancy is required in the structure that contains a JADU. Since January 1, 2026, though, Government Code section 66333 says owner-occupancy isn’t required if the JADU has separate sanitation facilities. Because the chapter defers to state law where they conflict, a JADU with its own bathroom shouldn’t carry that requirement. Confirm the details for your plan with the city.
Rental length is the other rule to know: in Livermore, “no ADU shall be rented for a period less than 30 days.” Short-term rentals fall under Municipal Code Chapter 5.90, which bars them in any ADU that got its building permit on or after January 1, 2020. If your ADU is older than that, check with the city before you rent it short term.
How long does an ADU permit take in Livermore?
Three clocks apply, and a pre-approved plan speeds up the review:
- Completeness, 15 business days. The city must tell you in writing whether your application is complete, and if it misses that deadline, the application is deemed complete (Government Code section 66317).
- Decision, 60 days. A complete ADU or JADU application that isn’t approved or denied within 60 days is deemed approved, unless you asked for a delay (Chapter 11.30).
- Review, 7 or 15 business days. Applications using a city pre-approved ADU plan are reviewed in 7 business days, rather than 15 for standard applications.
What does an ADU cost in city fees?
A pre-approved plan carries a flat $1,000 plan review fee paid to the city. Additional construction and inspection fees still apply and vary by plan, and the flat fee doesn’t include the designer’s fees.
Impact fees depend on size, per Livermore’s development impact fee sheet effective July 1, 2026 and Government Code section 66311.5:
- 750 square feet or less: no impact fees.
- Larger ADUs: impact fees are charged proportionately in relation to the square footage of the main home.
- JADUs: state law bars impact fees on a JADU of 500 square feet or less, and Livermore caps JADUs at 500 square feet.
Property taxes: only the new part is reassessed
According to the California State Board of Equalization (BOE), completed new construction triggers a reassessment, absent an exclusion. The new construction gets a base year value equal to the market value the assessor estimates it added, and “the value of the existing property is not affected.”
A garage conversion counts. The BOE lists “conversion of a garage, unfinished basement, or attic into a living area” as new construction.
Expect a supplemental bill first. The Alameda County Assessor says new construction triggers a supplemental tax bill from the date of completion. The next year, the added assessment joins your regular annual bill, due in December and April.
What an ADU adds to a Livermore home
An ADU adds living space you can use or rent on terms of 30 days or longer: a long-term rental, guest space or a home office. What it adds to the price depends on the property, how the unit was built and permitted, and what buyers pay nearby, so there’s no single figure to count on.
Buying a home with an ADU, or with a garage you’d like to convert? Talk to your lender early about how your loan program treats rental income. Our guide to California down payment assistance for first-time buyers covers the programs available here, and our guide to buying a fixer-upper in the Tri-Valley covers homes with room to grow.
Selling instead? See which renovations actually pay off when you sell, then get a free home valuation based on recent local sales. More on prices: Livermore home values in 2026.
The Mony Nop Real Estate Team is with Compass and works across Livermore, Pleasanton, Dublin, San Ramon and Danville, with 400+ clients served. If an ADU is part of your plans to buy or sell, get in touch with our team.
Frequently Asked Questions
Can I have an ADU and a JADU on the same lot in Livermore?
Yes. On a lot with an existing single-family home, Livermore’s ADU chapter permits one or all of three units: one conversion ADU, one detached or attached ADU, and one junior ADU. A JADU has to be within the home and can be up to 500 square feet. Detached ADUs are capped at 850 or 1,000 square feet, depending on bedrooms.
Do I have to replace the parking if I convert my garage?
No. Livermore’s ADU chapter says that when a garage, carport or parking space is demolished or converted to build an ADU or JADU, replacement parking isn’t required. The city also requires no ADU parking space when your permit application includes a conversion ADU or a junior ADU.
Can I rent my Livermore ADU as a short-term rental?
Livermore’s ADU chapter says no ADU may be rented for less than 30 days. Its short-term rental chapter separately prohibits short-term rentals in any ADU that got its building permit on or after January 1, 2020. If your ADU is older, check with the city first. Rentals of 30 days or longer are allowed.
Will adding an ADU raise my property taxes?
Only for the new part. The State Board of Equalization says completed new construction triggers reassessment of the added value, while the value of the existing property isn’t affected. In Alameda County you’ll get a supplemental bill from the completion date, and the next year the added assessment joins your regular annual tax bill.
About the author
Mony Nop has held a California real estate license since 2007 (DRE# 01813021) and spent 17 years with the Livermore Police Department. The two careers overlapped: he started in real estate part time while still an officer, then moved to real estate full time. He leads the Mony Nop Real Estate Team at Compass.
Sources
- City of Livermore, Development Code Chapter 11.30, Accessory Dwelling Units and Junior Accessory Dwelling Units, retrieved 2026-09-30
- City of Livermore, former Development Code Part 6 (section 6.03.120), retrieved 2026-09-30
- City of Livermore, City Council meeting record, adoption of Ordinance 2176, retrieved 2026-09-30
- City of Livermore, Municipal Code Chapter 5.90, Short-Term Rentals, retrieved 2026-09-30
- City of Livermore, Pre-Approved Accessory Dwelling Unit (ADU), retrieved 2026-09-30
- City of Livermore, Development Impact and Connection Fees, effective July 1, 2026, retrieved 2026-09-30
- California Government Code sections 66311.5, 66315, 66317 and 66333, retrieved 2026-09-30
- California Department of Housing and Community Development, ADU Handbook, retrieved 2026-09-30
- California State Board of Equalization, New Construction, retrieved 2026-09-30
- Alameda County Assessor, Renovations and New Construction, retrieved 2026-09-30
