# California AB 956: Two Detached ADUs on One Lot Starting 2027

*Published 2026-10-04 by 1 Smart Build*

Starting January 1, 2027, AB 956 lets California homeowners build two detached ADUs on a single-family lot. Here's what it means for LA.

Big news for LA homeowners. On September 29, 2026, Governor Newsom signed AB 956. Starting January 1, 2027, cities in California have to approve **two detached, new-construction ADUs** on a lot with a single-family home, as long as the project meets state rules. Until now, that fast-track pathway only covered one detached ADU.

Here's what changes, what doesn't, and how to tell if your lot can actually fit two.

## Key Takeaways
- AB 956 updates Government Code Section 66323 from one detached ADU to two detached ADUs on a single-family lot.
- It takes effect January 1, 2027.
- Cities can cap each of those ADUs at 800 sq ft of living space under this pathway.
- Side and rear setbacks can be as small as 4 feet.
- If you build two detached ADUs this way, the city doesn't have to approve a new Junior ADU on that same lot.
- HOAs still can't effectively block an ADU that state law protects.

## What AB 956 Actually Changes
California already makes cities approve certain ADUs "ministerially." That means no public hearing and no discretionary review. If the plans meet the standards, the city signs off. Section 66323 lists which ADUs get that treatment. Before AB 956, it was one detached new-construction ADU next to your house. Now it's two.

So on the right lot, you could have your main house plus two separate backyard homes. That's three units on what used to be a one-house property.

## How Big Can Each ADU Be?
Under this pathway, a city can limit each detached ADU to 800 sq ft of livable space. Two 800 sq ft units adds up to about 1,600 sq ft of new housing. Height, fire access and building code still apply, and your city's own ADU ordinance may allow bigger units through a different route. We check both before we draw anything.

## Setbacks: The 4-Foot Rule
The two detached ADUs can sit as close as 4 feet from the side and rear property lines. That matters a lot in Los Angeles, where plenty of backyards are long and narrow. Still, 4 feet isn't a guarantee you can build anywhere. Easements, sewer lines, power lines, trees, slopes and fire department access can all push a unit around.

## What About Garage Conversions and JADUs?
Section 66323 also covers ADUs built inside existing space, like a garage conversion. Depending on your property, a conversion might combine with detached units. But there's a catch: once you build two detached ADUs under this provision, the city isn't required to approve a new Junior ADU on that lot. So the order you build in matters. Plan the whole site first, then pick which units to build and when.

## HOA Rules Got Tighter (for HOAs)
State law already limits how much an HOA can restrict a legal ADU. AB 956 changes the wording from lots "zoned for single-family residential use" to lots "zoned to allow single-family residential use." That widens the protection to more properties. HOAs can still set reasonable rules, but they can't use them to effectively ban a protected ADU.

## Does Every Lot Qualify for Two ADUs?
No. The law opens the door, but your lot still has to physically and technically work. Before you count on two units, check:

- Usable backyard area and lot shape
- Existing structures and any unpermitted work
- Easements and utility locations
- Sewer or septic capacity
- Electrical service size (two units often means a panel or service upgrade)
- Fire access, hillside or fire-zone rules
- Grading, soils and drainage

A feasibility review up front saves you from paying for plans that can't get built.

## Why Two Smaller ADUs Can Make Sense
Some owners will want one big ADU. Others will like two smaller ones. Two units can give you a place for your parents and one for a grown kid. Or one for family and one to rent. Or two rentals. It gives you more options down the road.

## What to Do Before January 2027
The law isn't in effect yet, but design and engineering take months. If you start now, you can have plans ready to submit as soon as it kicks in. Here's the order we follow:

- Site review: lot size, setbacks, utilities and access.
- Layout options: one ADU vs. two, and where a garage conversion fits.
- Budget and financing for qualified homeowners.
- Plans, engineering and Title 24.
- Permits, then construction through final inspection.

We handle design, permits and the build in-house, so you've got one team the whole way. Want to know what your lot can fit? Start here: [ADU and garage conversion services](https://1smart.build/services/adu-garage-conversion), or call 1-866-419-8840.

## FAQ

### When does AB 956 take effect?
January 1, 2027. Governor Newsom signed it on September 29, 2026.

### Can I build two detached ADUs on my single-family lot?
Starting in 2027, cities must approve two detached new-construction ADUs on a qualifying single-family lot if the project meets state standards. Your lot still has to fit them.

### How big can each ADU be?
Under this pathway, a city can limit each detached ADU to 800 sq ft of living space.

### Can I still add a Junior ADU?
If you build two detached ADUs under this provision, the city isn't required to approve a new JADU on that lot. Plan the full site before you build.

### Can my HOA stop me?
HOAs can set reasonable rules, but they can't effectively prohibit an ADU protected by state law.

*This article is general information, not legal advice. Rules depend on your city and property.*

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