County directory

Solano County ADU rules

Each place name links to that city or county's own ADU page. Places with a 'See our rules summary' button also have our plain-language summary of the local ADU rules, with sources. Each place below says whether we show local rules or California state rules.

Places in Solano County

Benicia (opens the government site in a new tab)See our rules summary
Showing Benicia city rules
These are Benicia's own ADU rules on file, shown with the California state rules they build on. Each item says which is which.
Where a Benicia rule may conflict with state law or is being challenged, we show the California state rule instead. This covers a size cap on ADUs inside the home, a rule that keeps detached ADUs out of the front yard, and historic-district siting rules.
Dixon (planning page) (opens the government site in a new tab)
Showing California state rules because Dixon's local rules may conflict with state law or are being challenged
We show the state rules for a one-detached-or-one-converted ADU limit, a two-detached-ADU limit on multifamily lots, a cap on attached ADUs at 50% of the home or 1,200 sq ft (whichever is less), an owner-occupancy rule for every junior ADU, and a subjective design rule. Check with Dixon about how it handles this today.
Fairfield (opens the government site in a new tab)
Showing California state rules because Fairfield's local rules may conflict with state law or are being challenged
We show the state rules for an ADU section that cites the old state ADU law, a cap on attached ADUs at 50% of the home or 1,200 sq ft (whichever is less), a 16-foot height cap, and an owner-occupancy rule for every junior ADU. Check with Fairfield about how it handles this today.
Rio Vista (opens the government site in a new tab)
Showing California state rules because Rio Vista's local rules may conflict with state law or are being challenged
We show the state rules for ADU rules from 2021 that cite the old state ADU law and limit multifamily lots to two detached ADUs. Check with Rio Vista about how it handles this today.
Suisun City (planning page) (opens the government site in a new tab)
Showing California state rules
We couldn't read this city's ADU code yet, so we're showing California state rules. Check with the city before you plan.
Planning page: https://www.suisun.com/Departments/Development-Services/Planning
Vacaville (opens the government site in a new tab)
Showing California state rules because a local rule change is pending
A local rule change is pending. The City replaced its ADU rules on February 10, 2026 (Ordinance 2013), and its online code shows that text out of place, so it could not be fully reviewed for this summary. We'll add the new local rules after they take effect and we've reviewed them.
Vallejo (opens the government site in a new tab)See our rules summary
Showing Vallejo city rules
These are Vallejo's own ADU rules on file, shown with the California state rules they build on. Each item says which is which.
Where a Vallejo rule may conflict with state law or is being challenged, we show the California state rule instead. This covers owner-occupancy rules for junior ADUs, a 50% size cap for attached and conversion ADUs, and a 15-foot front setback.
Unincorporated Solano County (opens the government site in a new tab)
Showing California state rules because a local rule change is pending
A local rule change is pending. The County adopted changes to its ADU rules on August 25, 2026 (ZT-26-02), and its online code could not be confirmed as updated when this research summary was prepared. We'll add the new local rules after they take effect and we've reviewed them.

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