California AB 956: Two Detached ADUs Coming in 2027

California AB 956: Two Detached ADUs Coming in 2027

California AB 956 may create a pretty interesting new opportunity for homeowners starting in 2027.

A new California law, AB 956, expands the state’s ADU rules and allows qualifying single-family properties to pursue two detached, new-construction accessory dwelling units instead of one through the streamlined approval process.

California AB 956 is important because it expands the streamlined ADU pathway for qualifying single-family properties.

That could be a big deal.

For the right homeowner, it may create additional space for family.

For someone looking to generate rental income, it could create new opportunities.

And for real estate investors, it may completely change the way they look at the potential of an existing single-family property.

But there is another part of this conversation that I think deserves just as much attention:

How are you going to pay for it?

Because if you already own a home with a great first-mortgage rate, refinancing your entire mortgage to pull out construction money may not always be the smartest first option.

Let’s break down what is changing, what homeowners should understand, and some of the financing strategies worth exploring.

What Is California AB 956?

AB 956 is a new California law affecting accessory dwelling units, commonly known as ADUs.

Beginning January 1, 2027, the law expands the streamlined approval pathway for a qualifying lot with an existing or proposed single-family dwelling to include two detached, new-construction ADUs.

Under this provision, local agencies may impose certain limitations, including a maximum floor-area limitation of 800 square feet of livable space for each detached ADU and applicable height requirements.

The law also addresses side and rear setbacks, with the streamlined provision applying to qualifying detached ADUs with setbacks of no more than four feet.

In simple terms:

A qualifying California single-family property may have the opportunity to add two separate detached ADUs.

That is a significant change.

Think Three Potential Living Units on One Property

Imagine an existing single-family home with enough usable lot space.

You already have the main house.

Then, depending on the property, local requirements, permitting, design, utilities and other factors, you may potentially be able to build two detached ADUs.

That creates some interesting possibilities.

A homeowner could potentially:

• Live in the primary residence and rent both ADUs.
• Live in the primary residence and use one ADU for family while renting the other.
• Create housing for aging parents or adult children.
• Use an ADU for long-term rental income.
• Add flexibility to a property that may eventually serve multiple generations.

For an investor, the economics may also become worth exploring because an existing single-family property could potentially support multiple rental units.

Notice I said potentially.

This is not as simple as saying every backyard in California can suddenly fit two 800-square-foot houses.

The lot still matters.

The design matters.

Utilities matter.

Building codes matter.

Fire and safety requirements matter.

Construction costs matter.

And local implementation still matters.

Before somebody buys lumber or starts drawing plans, they should talk with the appropriate local planning professionals, contractors and other qualified experts.

800 Square Feet Is Not a Minimum

This is an important distinction because I have already seen this discussed incorrectly.

AB 956 does not say that each new ADU must be at least 800 square feet.

Rather, under this streamlined provision, a local agency may impose a floor-area limitation of not more than 800 square feet of livable space on each detached new-construction ADU.

Those are very different things.

Depending on the property and the homeowner’s goals, smaller units may actually make much more sense.

Two thoughtfully designed smaller ADUs could potentially provide better use of a lot than trying to maximize every possible square foot.

This is where good planning becomes incredibly important.

The Rental Income Opportunity Is Interesting - But Run the Numbers

Whenever people hear “two ADUs,” the immediate reaction is often:

Two more rents!

Maybe.

But rental income alone does not tell you whether a project makes financial sense.

You also need to understand:

• Construction costs
• Architectural and engineering costs
• Permitting
• Utility connections
• Property-tax implications
• Insurance
• Financing costs
• Maintenance
• Vacancy assumptions
• Market rents
• The time required to complete the project

A project that generates additional rent can still be a bad investment if the cost to create that rent is too high.

On the other hand, the right property, construction budget and financing structure may create an extremely interesting long-term opportunity.

The point is not:

“Build two ADUs because California says you can.”

The point is:

Now that this option may exist, let’s determine whether it actually makes financial sense for your property.

That is a much better conversation.

Already Have a Low Mortgage Rate? Think Before You Refinance It

This may be the biggest financing lesson in this entire conversation.

Let’s say you bought or refinanced several years ago and have a first mortgage with a very low interest rate.

Now you want several hundred thousand dollars to build one or two ADUs.

One possible solution would be a cash-out refinance.

But think about what that does.

You are not only borrowing the additional money needed for construction.

You may also be replacing your entire existing mortgage balance with a new loan at today’s available rate.

Depending on your existing mortgage, that can be expensive.

I tell people all the time:

Do not automatically disturb cheap money just because you need additional money.

First, look at the entire financing picture.

If your existing first mortgage is working for you, there may be situations where leaving that loan alone and financing only the additional funds needed for the project produces a better overall strategy.

Home Equity May Be Part of the Solution

For homeowners with sufficient equity, a HELOC or other home-equity financing may be worth evaluating.

Instead of refinancing the entire first mortgage, a homeowner may be able to access a portion of the equity separately.

Depending on the program, this could potentially allow someone to:

• Keep the existing first mortgage in place
• Access funds for construction or improvements
• Borrow based on available equity and qualification
• Structure financing around the actual amount needed for the project

There are multiple types of home-equity products available, and they do not all work the same way.

Some are lines of credit.

Others provide fixed-rate options.

Depending on the program, certain products may work for owner-occupied properties while others may allow investment properties.

Qualification can depend on credit, income, equity, property type and the specific loan program.

That is why the financing conversation should happen before construction begins.

Do Not Finance a Long-Term Project With the Wrong Short-Term Debt

Another mistake I would try to avoid is automatically reaching for credit cards or other expensive short-term debt simply because it is easy to access.

Building an ADU is a major real estate project.

The financing should be approached like one.

You want to understand:

How much will I actually need?

When will I need the money?

What will the monthly payment be?

Will I make payments during construction?

What happens when construction is complete?

How much rent could the finished unit realistically generate?

And what is my exit strategy?

Those questions matter more than simply asking, “What interest rate can I get?”

Start With the Finished Project and Work Backward

If somebody called me today and said:

“Tim, I want to build two ADUs in my backyard in 2027. What should I do?”

I would not start with the loan.

I would start with the plan.

What are you building?

How much will the project cost?

What will the finished property look like?

Will you rent both units?

Will family occupy one?

What are realistic market rents?

How much equity is currently available?

What mortgage do you already have?

What is your current payment?

How much additional monthly payment are you comfortable taking on?

Then we can start comparing financing options.

That is how I think lending should work.

The loan is not the strategy. The loan should support the strategy.

Realtors Should Understand This Too

This is not only a homeowner conversation.

If you are a California Realtor, this law gives you another reason to look at a property differently.

A buyer may walk into a house and see an oversized backyard.

An experienced real estate team may see possibilities.

California AB 956 also gives Realtors another reason to understand the hidden potential inside certain properties.

Could an ADU work?

Would two ADUs make sense beginning in 2027?

Could rental income change how the buyer evaluates the property?

Maybe the property could work for multigenerational living.

Or perhaps it becomes more attractive to an investor.

None of that means a Realtor needs to become an architect, contractor, city planner or lender.

It means knowing when to bring the right professionals into the conversation.

That is where the team matters.

The Opportunity Is Bigger Than Just “More Units”

I think the exciting part of California’s continued ADU changes is the flexibility they can create.

Housing does not look the same for every family.

Some people need a place for their parents.

Other families want adult children to have their own space without moving far away.

Homeowners may be looking for rental income.

Investors may want to improve the income potential of an existing property.

And others may simply want the flexibility of additional living space.

AB 956 could create more options for all of those situations.

But an opportunity only becomes a good opportunity when the numbers make sense.

Before You Build, Build the Financial Plan

If you are considering adding one or two ADUs to a California property, do not wait until you have signed a construction contract to figure out financing.

Start earlier.

Talk with the city or a qualified ADU professional.

Understand what can realistically be built.

Get realistic construction estimates.

Research achievable rents.

Talk with your insurance professional.

Talk with your tax professional about potential tax implications.

And talk with a lender about the financing options available based on your property, equity and goals.

Then put all of those pieces together.

That is where good decisions happen.

California AB 956 Creates Another Option. Strategy Determines Whether You Should Use It.

I am excited about what this could mean for California homeowners and investors.

Two detached ADUs on a qualifying single-family property could create opportunities that did not exist under the same streamlined pathway before.

But I would never tell someone:

“You can build two ADUs now, so go do it.”

I would say:

Let’s figure out what you can build, what it will cost, how you would finance it, what income it may generate, and whether the entire project makes sense.

That is the conversation worth having.

And if you already have a low-rate mortgage?

Before replacing it, let’s look at whether there is a way to leave that first mortgage alone and use your equity more strategically.

That could make a very big difference.

If you are a California homeowner, investor or Realtor and want to talk through the financing side of an ADU project, let’s connect:

https://calendly.com/mortgage_manfro/chat-with-mm

Tim Manfro
Mortgage Manfro | Loan Advisor Group
Give. Guide. Educate.

This information is for educational purposes only and is not legal, tax, investment, construction, zoning or lending advice. ADU eligibility, local requirements, financing options, loan terms and qualification requirements vary. Consult the appropriate licensed and qualified professionals regarding your specific property and circumstances.