ADU Questions · 2026
What Is AB 1033, California's ADU Condo Law?
AB 1033 is a California law, signed in 2023, that allows cities to adopt a local ordinance letting a homeowner map an ADU as a condominium and sell it separately from the main house. It does not apply automatically statewide. A city has to opt in with its own ordinance before AB 1033 does anything in that jurisdiction.
The short version: AB 1033 gave California cities the option to let ADUs be sold as separate condominiums instead of only rented, but each city has to pass its own ordinance to turn that option on.
What the law actually changes
Before AB 1033, an ADU was tied to the main home in every practical sense. You could rent it out, house family in it, or use it as a home office, but you could not sell just the ADU. The property sold as one unit, main house and ADU together, no matter how independent the ADU felt on the ground.
AB 1033 opens a new path: condominium mapping. When a city adopts the ordinance, a homeowner can subdivide their property into separate condominium interests, typically one for the main home and one for the ADU, and sell each interest on its own. The ADU becomes a legal, separately-owned unit rather than a rentable extension of the main house.
This is the same legal mechanism that already lets condo buildings sell individual units. AB 1033 extends the option to single-family lots with an ADU, but only where the local city has said yes.
Why this was a meaningful change
Before AB 1033, an ADU could only generate value through rent, or by increasing the resale value of the whole property when the owner eventually sold both units together. There was no way to cash out the ADU on its own, or to sell it to a separate buyer while keeping the main house.
That mattered for a few real scenarios: a parent who wants to sell the back unit to an adult child directly, an owner who wants to recover some of the ADU’s construction cost as a lump sum instead of collecting rent over years, or a multigenerational property where two family households want separate legal ownership instead of shared title.
AB 1033 does not force any of that to happen. It just removes a legal barrier, city by city, so it becomes possible where local government allows it.
Opt-in, not automatic: what that means for you
This is the detail that trips people up. AB 1033 is enabling legislation, not a statewide mandate. Until a specific city adopts its own local ordinance under AB 1033, condominium-mapped ADU sales are not available there, even though the state law exists.
| Question | Answer |
|---|---|
| Does AB 1033 apply everywhere in California automatically? | No. Only in cities that have adopted their own ordinance. |
| Who decides if it applies in your city? | The city council or county board, through local ordinance. |
| How do you find out if your city has opted in? | Contact your city’s planning or building department directly. |
| Does adopting AB 1033 change setback, height, or size rules for ADUs? | No, those statewide ADU rules stay the same either way. |
Because adoption is happening city by city and the landscape keeps shifting, the only reliable way to know your specific city’s status is to ask the local planning department directly, not to assume based on what a neighboring city has done.
How this connects to building with Framework First
AB 1033 is a legal and financial planning question that sits alongside, not instead of, the physical build. Framework First’s project pricing includes a permitting budget along with plans, foundation, the factory build, crane delivery, utility hookups, appliances, and final inspection, and that applies the same way whether an ADU is ever going to be condo-mapped or not. Exact permit costs are set by each city and county, so they’re property-specific and get confirmed in your feasibility study rather than assumed upfront, and property-specific site work like septic upgrades or retaining walls sits outside the listed model pricing, though we handle it in-house as part of your contract so the project stays with one builder.
If separate sale down the road is part of your thinking, it is worth raising early. A feasibility study is the right place to start: it looks at your specific lot and local rules before you commit to a model and layout. From there, browsing the full model lineup or running numbers on the pricing calculator will help you see what’s realistic on your property.
Frequently asked questions
Does AB 1033 mean I can sell my ADU right now?
Only if your specific city has adopted a local ordinance under AB 1033. The law gives cities the option, it does not automatically activate condo-mapped ADU sales everywhere. Check with your city’s planning department to confirm local status before assuming it applies.
When was AB 1033 signed into law?
AB 1033 was signed in 2023 as part of California’s continuing series of ADU-focused legislation aimed at expanding housing options and giving homeowners more flexibility with the units they build.
Does AB 1033 change how big my ADU can be or where it has to sit on the lot?
No. AB 1033 is about ownership structure, not physical ADU rules. Statewide standards, like the 1,200 square foot maximum size and the 4 foot side and rear setbacks for new construction, stay exactly the same regardless of whether your city has adopted AB 1033.
If my city hasn’t adopted AB 1033, can I still get value from my ADU?
Yes. Renting the ADU out, using it for family, or simply increasing your property’s overall resale value all remain available everywhere in California, regardless of AB 1033 adoption. Condominium mapping under AB 1033 is one additional option in cities that have opted in, not a requirement to benefit from an ADU.
Is condominium mapping the same as just splitting my lot into two lots?
No. AB 1033 condominium mapping creates separate ownership interests within what can still be a single legal lot, similar to how a condo building works. That is a different legal process than a lot split, such as one done under SB9, which divides the underlying land itself. If you’re weighing lot-split options, see SB9 lot splits in California for that separate topic.
Curious what an ADU could look like on your property, condo mapping aside? Start with a feasibility study to see what’s possible on your lot.