Two ADUs on One Lot, By Right: What California Just Handed Sacramento Homeowners

ADU Builder editorial – Sacramento, CA

On September 29, 2026, the Governor signed AB 956. According to the author’s description, it allows up to two detached ADUs by right on single-family lots, and HOAs cannot block them. That headline – two ADUs on one lot in California, with no HOA veto – deserves your attention. Here is the honest part: the final bill text and effective date are not yet published in plain-language summaries, and new California laws normally take effect January 1 of the following year. So verify the details for your property before you design around them. What you can rely on today is existing law. California allows ADUs on single-family lots statewide. Review is ministerial, with no public hearing. Cities cannot ban ADUs. Since January 1, 2026, development impact fees are barred on ADUs of 750 square feet or less. We check your lot against all of it, free.

Concept rendering – illustrative, not a completed project.

What did California actually sign on September 29, 2026?

The Governor’s office listed AB 956 in its September 29 housing signing release. According to the author’s description, AB 956 allows up to two detached ADUs by right on single-family lots, and HOAs cannot block them.

Read that twice. Two detached units on a single-family lot, and your HOA does not get a vote. If it holds up in the final text, it changes what two ADUs on one lot in California means for every homeowner who has been told no.

Now the part most blog posts skip. We have the author’s description. We do not have a plain-language summary of the final bill text, and neither does anyone else we trust yet. The final text and the effective date are not yet published in the summaries we can point you to. New California laws normally take effect January 1 of the following year, which would point to January 1, 2027. Write that date in pencil, not ink.

Here is what we will not do. We will not tell you how big each unit can be or how far it must sit from your fence. Those numbers are not in front of us, and a guess from a contractor can cost you a set of plans. When you want your property checked against the rules, we do that free.

What can you build in Sacramento right now, before any of this kicks in?

Plenty. The state housing department, HCD, keeps the ground rules on its accessory dwelling unit page. California allows ADUs on single-family lots statewide. Review is ministerial, which means non-discretionary: your city checks your plans against written rules, and there is no public hearing where a neighbor gets to argue. Cities cannot ban ADUs.

That is better than many homeowners expect. Some still picture a packed council chamber and a project that dies on a show of hands. For an ADU, that scene does not apply.

Inside those rules you already have choices. A detached ADU is a small separate home in your backyard, and a garage conversion turns square footage you already own into a place to live. A junior ADU, or JADU, is different: capped at 500 square feet and built inside your existing home. Many lots can already combine a JADU and an ADU. And since 2025, SB 1211 has allowed up to 8 detached ADUs on lots that already have a multifamily building.

If you want the full tour, start with our complete ADU guide. Then come back, because the two-unit news is the part that moves.

What does by right mean for a homeowner?

It means the city’s job is to check your plans against the written rules. Deciding whether the neighbors are happy is not part of that job. That is ministerial review, and it is the reason an ADU moves differently from a project that needs a hearing.

Speed is part of it. Since January 1, 2026, under SB 543, agencies must determine whether your application is complete within 15 business days. Know exactly what that says. It is a completeness deadline. It is not a promise that your permit shows up in 15 business days, and anyone who tells you otherwise is selling something. For how permits and zoning actually flow, read our ADU permits and zoning page.

Put ministerial review next to a 15-business-day completeness check and the lesson is plain: the homeowner who submits a clean, complete set of plans is the one who gets to use those rules. That is design-build work done well – plans drawn to the rules from day one.

Can your HOA stop you from building two ADUs?

If you live under an HOA, this is the line to read twice. According to the author’s description of AB 956, HOAs cannot block the two detached ADUs it covers. Description, not final text. The same hedge applies as above: the final bill text and effective date are not yet in plain-language summaries.

So treat your HOA documents as live until you have verified how the new law applies to your property. Pull your CC&Rs and find the architectural review language, then keep both next to the bill text when it lands. Checking how it applies to your lot is a job we do free.

What happens to impact fees with two ADUs?

Fees are where a second unit can get expensive, so slow down here.

Existing law first, because you can rely on it. Since January 1, 2026, SB 543 has barred development impact fees on ADUs of 750 square feet or less.

Now the new one. SB 1117 was also signed September 29, 2026. Per its sponsor, for the first two ADUs on a property, impact fees apply only to square footage above 750. It passed the Senate 37-0. Same hedge as AB 956: the final text and effective date are not yet in plain-language summaries, and new laws normally take effect January 1 of the following year. Verify before you plan around it.

We are not quoting a fee number for your address in a blog post, because we would be making it up. Your number belongs in a written estimate for your address. To see where fees fit in the full picture, read our ADU cost and financing breakdown.

What would two ADUs cost to build, and what could they rent for?

Ballpark planning ranges only. Treat every number in this section as a way to think, not a quote. In the Sacramento region, a detached ADU runs about $250-$400 per square foot to build, and a garage conversion about $150-$260 per square foot. The rents below are ballpark ranges for the Sacramento region. Verify them against live listings before you trust them.

Planning ranges. The build column is simply unit size times $250-$400 per square foot. Not a quote, not a rent guarantee.

Run a garage example. Say your conversion comes to 400 square feet. At $150-$260 per square foot, that is a $60,000-$104,000 planning range, with a ballpark rent of $1,400-$1,900 per month for that size.

Now picture two detached units of about 600 square feet each. At the ballpark rents, the pair brings in $3,400-$4,600 per month on paper. At the ballpark build range, the pair costs $300,000-$480,000 to build. On paper is the phrase that matters. Before you count a dollar of that as profit, subtract vacancy, property taxes, insurance, loan payments and upkeep. Those are your numbers, and they are not in this post.

Compare that with building one unit first. A single 600 square foot unit at the ballpark rent brings $1,700-$2,300 per month on paper, with a build range of $150,000-$240,000. Whether a second unit is worth it depends on how the first one performs and on what your lot allows.

Is building two ADUs the right move for your lot?

Maybe, maybe not. Here is the straight answer: it depends on your lot and on what you want out of the next ten years.

Some owners want rent. Others want a place for a parent or an adult child. Those goals lead to different floor plans, so decide what each unit is for before you draw anything.

Two units means more to plan and more to pay for up front. If you rent both, it also means two tenants to manage. Some owners love that, and others find one unit plenty. Neither answer is wrong.

Ask yourself a blunt question: could you carry the loan payment if a unit sat empty for a few months? If the answer is no, build smaller or build one.

Then there is timing. You can build today under the rules already in place, or you can wait for the final text of AB 956 and build to it. Waiting has a cost, and rushing has a cost. The middle path is to get your lot reviewed now, learn what you can build today, and know what to watch for when the final text arrives. Do not pour a foundation around a rule you have not read.

What should you do this month?

Short list. You can finish it in a weekend.

• Bookmark the Governor’s release above and watch for the final text of AB 956 and SB 1117.
• If you have an HOA, pull your CC&Rs and mark the architectural review language.
• Decide what each unit is for, whether that is rent or family.
• Ask anyone quoting you a size or a setback for AB 956 to name the source. If they cannot, do not use the number.
• Keep your budget in ranges until a written estimate exists for your address.
• Book the free on-site written estimate: request your free ADU quote.

ADU Builder is a Sacramento design-build contractor working within roughly 200 miles of the city. The on-site written estimate is free and carries no obligation. Call (916) 432-0333 and we will also check how AB 956 and SB 1117 apply to your property once the final text is out.

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