Short answer: In much of the Bay Area, an ADU short-term rental is not allowed. San Mateo, Burlingame, Daly City, Hercules, and Piedmont bar it, Alameda is working toward the same, and for ADUs approved through California’s streamlined ministerial pathway, state law (Gov. Code § 65852.2(e)(4)) requires rentals longer than 30 days regardless of city rules. Confirm both before you list. Updated October 20, 2026. General information, not legal advice; verify with your city planning department.
If you’re self-managing a short-term rental and you’ve been eyeing the in-law unit, converted garage, or backyard cottage on the same lot as a second listing, it’s worth checking something before you photograph it for Airbnb: whether the unit is even legally allowed to be a short-term rental at all. Across the Bay Area, the answer is increasingly no — and for a specific category of ADUs, that answer doesn’t come from your city council. It’s already written into state law.
Which Bay Area cities ban ADU short-term rentals?
San Mateo’s short-term rental ordinance (Chapter 5.66, in effect since February 1, 2021) is explicit and simple: “Accessory Dwelling Units (ADUs) cannot be used for short-term rentals,” full stop — they’re not eligible to register, no exceptions listed. Burlingame’s short-term rental program cites state law as the basis for barring ADU short-term rentals outright. And per an October 7, 2026 regulatory roundup from trade publication Rental Scale-Up, Alameda’s still-pending ordinance (final passage was scheduled for October 6 but withdrawn from that agenda; no new vote date has been confirmed as of this writing) would join Burlingame, Daly City, Hercules, and Piedmont in barring short-term use of ADUs and JADUs — with one carve-out in Alameda’s draft: legacy hosts whose ADUs were built before 2017 would be exempt.
Does California state law require 30-day minimum ADU rentals?
Here’s the detail most city-level coverage skips: for one specific category of ADU, the 30-day-plus minimum isn’t something a city chose to adopt — it’s a mandatory floor set by the state. California Government Code § 65852.2 treats two kinds of ADUs differently. Under subdivision (a)(8), for most ADUs added to a lot with an existing single-family home, a city may require rentals of 30 days or longer — that’s a local option, and a city that hasn’t adopted it technically hasn’t restricted that unit’s rental term (though plenty of Bay Area cities have). But under subdivision (e)(4), for ADUs approved through the state’s streamlined ministerial pathway — a specific, narrower category — the law says a local agency shall require rentals longer than 30 days. That’s not optional, and it applies whether or not your particular city has ever passed its own short-term rental ordinance.
In practice, that means two ADUs on two otherwise-similar Bay Area properties can have completely different legal outcomes, and the difference often has nothing to do with which city they’re in — it depends on which approval pathway built the unit in the first place. That’s not a detail any single city’s planning page is going to walk you through, because from the city’s perspective, the state already decided it.
What should you check before listing an ADU on Airbnb?
If an ADU on your property is part of the plan for additional short-term income, don’t start from “does my city have an ordinance” — start from two separate questions. First: is this specific ADU one of the ones the state already requires to be rented 30 days or longer, regardless of local rules? Second: has your city separately banned or restricted ADU short-term rentals on top of that, the way San Mateo, Burlingame, Daly City, Hercules, and Piedmont all have, and the way Alameda is still working toward? Either question answered wrong is the kind of mistake that shows up as a code violation notice, not a lost booking.
How much can a short-term rental earn in San Mateo?
Worth knowing as a starting point, not a verdict: San Mateo short-term rentals currently average a $246 nightly rate at 54% occupancy, working out to roughly $37,504 in average annual revenue (Rabbu market data, as of April 27, 2026). That’s a whole-property average across every size and condition of listing in the market — not a projection for a specific ADU, which typically commands a lower nightly rate than a full house — and it says nothing about whether a given ADU is even eligible to be listed in the first place. The order of operations matters: confirm eligibility first, then run the real numbers.
If you’re a self-managing owner weighing whether an ADU on your property could add income, or you’re not sure whether your existing ADU listing is actually compliant, our free listing audit checks both the state-law and city-ordinance status of the specific unit — not a generic answer, and never a guess — along with a conservative-to-upside revenue range from real comps.
Frequently asked questions about ADU short-term rentals
No. San Mateo’s short-term rental ordinance (Chapter 5.66, in effect since February 1, 2021) states that Accessory Dwelling Units cannot be used for short-term rentals, and ADUs are not eligible to register.
For some ADUs, yes. Under Government Code § 65852.2(e)(4), a local agency shall require rentals longer than 30 days for ADUs approved through the state’s streamlined ministerial pathway. For most other ADUs added to a lot with an existing single-family home, subdivision (a)(8) lets a city choose to require 30 days or longer.
San Mateo, Burlingame, Daly City, Hercules, and Piedmont bar short-term use of ADUs. Alameda has a pending ordinance that would do the same, with an exemption in its draft for legacy hosts whose ADUs were built before 2017. As of an October 7, 2026 roundup, no new vote date had been confirmed.
Rabbu market data (as of April 27, 2026) shows an average of $246 per night at 54% occupancy, or roughly $37,504 in annual revenue. That is a whole-property average, not a projection for an ADU, and it does not indicate whether a given ADU is eligible to be listed.
Sources: City of San Mateo, Short-Term Rental Ordinance; City of Burlingame, Short-Term Rental Program; Rental Scale-Up, “Updates in short-term rental policies this week” (Oct. 7, 2026); Hoodline, “Airbnb Showdown: Alameda Planners Weigh Crackdown on Short Stays” (July 11, 2026); California Government Code § 65852.2, subdivisions (a)(8) and (e)(4), as summarized via FindHOALaw and STR Law Map, California Short-Term Rental Laws: State Overview, cross-checked against the AB 976 (2023–24) bill text on LegiScan; Rabbu, San Mateo, CA Airbnb Market Data (as of April 27, 2026).