California ADU questions, answered from official sources.
加州 ADU 问题，
Ask about accessory dwelling units in ChatGPT or Claude, in English or Chinese. ADUwise finds the state law, city code, fee schedule or handbook page that answers it, and the answer links to it, so you can show your customer the original.
Our main house has no fire sprinklers. Can the city require sprinklers in a new ADU?
Generally, no—if sprinklers are not legally required for your main house. California law prohibits requiring them in the ADU in that situation. Building the ADU also cannot, by itself, trigger a sprinkler retrofit in the existing main house. (Gov. Code §66314(d)(12) (opens in a new tab), as of Jan. 1, 2026.)
The key distinction is “not required,” rather than simply “not installed.” For example, if a significant alteration independently makes sprinklers required for the main house, an ADU created afterward must also have sprinklers. (HCD ADU Handbook, p. 23 (opens in a new tab), as of Mar. 1, 2026.)
The new ADU must still meet fire-access and water-supply standards; sprinkler exemption does not waive those requirements. (State Fire Marshal Bulletin 25-004, p. 3 (opens in a new tab), as of Mar. 3, 2025.)
Which city is the property in, and are you also remodeling the main house?
How it works
使用方法
ADUwise isn't another app to learn. It adds the official sources to the ChatGPT or Claude you already use.
Add ADUwise to ChatGPT or Claude
Once, on a computer, with the step-by-step guide that comes with your account. After that it works in the ChatGPT phone app too.
Ask the way your customer asks
In English, Chinese or a mix of both. ADUwise looks up state law and the city's own code, fees and permit process.
Check the source
Each answer links the official pages it relies on and gives their dates, so you can show your customer the original.
Tested against web search alone
We asked ChatGPT's model the same 44 ADU questions with ADUwise and with web search alone. An answer passes when it has every fact the question needs and nothing the official text contradicts.
- With ADUwise
- 40 of 44 passed
- Web search alone
- 20 of 44 passed
With web search alone, 3 answers stated something wrong, such as one city's fees from last year's schedule. With ADUwise, none did.
How we measured: 20 questions we wrote from the official sources, asked in English and Chinese, 4 of them also in mixed Chinese and English, for 44 in all. They are the questions we used while building ADUwise. GPT-6.1 Sol, the model in ChatGPT, answered each once at high effort with web search on, through OpenAI's Codex, in October 2026. The judge, Claude Opus 5.5, checked every answer against the official text.
Code updates
法规更新
Changes to the state and city rules ADUwise covers. This page shows the last month; members see every week.
What ADUwise reported each week: laws and fees adopted or enacted, and changes that took effect.
Week of Oct 5, 2026
- UpcomingCalifornia state lawTakes effect Jan 1, 2027AB 956: two detached new ADUs on a single-family lot, up from one
Cities and counties must approve permits for two detached, newly built ADUs on a lot with a single-family home, where the rule now says one. The rule voiding deed and HOA restrictions that prohibit or unreasonably restrict ADUs also extends to any lot zoned to allow single-family homes, not only lots zoned for them.
Enacted Sep 29, 2026Text checked Oct 10, 2026
- UpcomingCalifornia state lawTakes effect Jan 1, 2027SB 1117: impact fees on a larger ADU charged only on the area above 750 square feet
For up to two ADUs on a lot, an impact fee on an ADU with more than 750 square feet of interior living space stays proportional to the main home's size and is charged only on the area above 750 square feet. The ban on impact fees for ADUs of 750 square feet or less stays.
Enacted Sep 29, 2026Text checked Oct 10, 2026
Changes already adopted or enacted that take effect on a later date, soonest first.
Jan 1, 2027in 80 days
- UpcomingCalifornia state lawTakes effect Jan 1, 2027AB 956: two detached new ADUs on a single-family lot, up from one
Cities and counties must approve permits for two detached, newly built ADUs on a lot with a single-family home, where the rule now says one. The rule voiding deed and HOA restrictions that prohibit or unreasonably restrict ADUs also extends to any lot zoned to allow single-family homes, not only lots zoned for them.
Enacted Sep 29, 2026Text checked Oct 10, 2026
- UpcomingCalifornia state lawTakes effect Jan 1, 2027SB 1117: impact fees on a larger ADU charged only on the area above 750 square feet
For up to two ADUs on a lot, an impact fee on an ADU with more than 750 square feet of interior living space stays proportional to the main home's size and is charged only on the area above 750 square feet. The ban on impact fees for ADUs of 750 square feet or less stays.
Enacted Sep 29, 2026Text checked Oct 10, 2026
Cities
覆盖城市
State law and state guidance apply in every California city, so ADUwise answers those anywhere. For these cities it also has the city's own code, fees and permit process.
Bay Area
- Cupertino
- Fremont
- Gilroy
- San José
- San Ramon
- Saratoga
- Sunnyvale
Asking about a city that isn't listed? ADUwise answers from state law and tells you that city's own rules aren't covered yet.
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