In January of 2017, the California Senate passed a new law, government code 65852.2, that makes building a granny flat a whole lot easier.

So, what does this new law mean and what are the granny flat regulations for California?

Maxable sat down with Jared Basler, Director of Strategic Initiatives of the Casita Coalition, to break down what California’s new Senate Bill means for accessory dwelling units.

All Prior Granny Flat Laws are Null and Void

Prior to 2017, granny flat laws were outlined separately in each of California’s 543 jurisdictions. That means each jurisdiction had passed its own granny flat ordinance — most of which placed incredible restrictions and fees on homeowners.

California lawmakers recognized the gross overregulation at the local level and signed government code 65852.2 into state law. Thankfully, these archaic regulations regarding minimum lot sizes, parking restrictions, you name it, are now null and void.

“This state law overrides all local jurisdictions,” said Basler. “The state of California needs more housing and they realize that to do that, they need to relax very restrictive and outdated laws.”

Jurisdictions Can Write Their Own Ordinance:

While California’s new state law regulates granny flat projects across the board with no exceptions, local jurisdictions still retain the legal right to draft their own ordinances — provided they exist within the framework of the new state law. This is why you may be able to do things that your friend five miles away can’t.

For example, jurisdictions can write an ordinance outlining:

  1. Legality of Short-Term Vacation Rentals
  2. Whether Owner Occupancy is a Requirement
  3. Maximum ADU Size

Find out if your jurisdiction has written its own ordinance here, or consult our regulations portal for a simplified, comprehensive version of your ordinance.

Now, let’s examine the California’s state standards.

granny flat regulations for California copy

Single Family Residence

Any single-family residence can now build a granny flat or accessory dwelling unit (ADU) on their property. Any existing structure, like a garage, can be converted into an accessory dwelling unit.

Not sure what your zone is? You can visit to figure it out, or contact Maxable.

Granny Flat Size Requirements

The new granny flat regulations state that the minimum size you can build your granny flat is 150 square feet. The maximum size is 50 percent of the size of the existing house, up to 1,200 square feet for attached units. The maximum detached unit size you can have is 1,200 square feet. Square footage is measured as accessible from the inside of the unit.

What if your house is only 800 square feet? Can you still build a unit that’s 1,200 square feet? Yes. Unless your jurisdiction put an ordinance restricting maximum build size.

granny flat regulations for california

Parking Requirements for Accessory Dwelling Units

No additional parking is required IF you’re converting an existing permitted space, like your garage or if you’re within half a mile of a transit stop.

If you don’t qualify for either of those, you will need to provide parking. Luckily, the law allows you to place parking anywhere on your lot, but it must be hardscaped for parking, meaning you can’t park a car on your lawn. Unlike previously, parking may now exist as a tandem in an existing driveway. One parking spot typically measures 10×18′. You’ll be required to add one parking spot per bedroom added.

Setback Requirements

If the structure is already permitted, like a garage, congratulations, there are no setback requirements!

Now, let’s say you decide to add a second story to your garage, then the setback rules DO apply and you need to have at least 5′ setbacks on the side and rear lot line.

What to Expect in Fees?

Here’s where the news is less great. Previously, building an accessory dwelling unit was extremely cost-prohibitive because the city charged the same impact fees as building a brand new house, which could be up to $80,000!

Basically, this new law said, “Ok, look, guys, fees need to be proportional to the impact the development has on the property.” This law stems from the Mitigation Fee Act. Since code 65852.2 didn’t specify exactly what “proportional” meant, a lot of cities said, “Ok, they are proportional.” Even though they didn’t make any changes to their fee structure. (Lazy!)

Impact fees should be redefined since these single-family homes have already paid impact fees when the original house was first constructed. Right now, fees range from $1,800-$85,000. In San Diego, you can expect to pay around $20,000 in fees to the city, potentially less if you’re converting space within an existing home.

Granny Flat Regulations in California

Historical Review Fees

A historical review will be required before your plans are approved if your home is older than 45 years. The city will look at your home in a vacuum and assess things like, have you made exterior changes? Are all the windows matching or are half vinyl? You’ll also be required to submit a copy of the building record. Historical reviews are typically several thousand dollars.

Can I Rent My Accessory Dwelling Unit?

You may rent your accessory dwelling unit, but your jurisdiction may place restrictions on short-term vacation rentals. For example, in San Diego, you cannot rent your granny flat legally on Airbnb.

Can You Permit an Illegally Built Structure?

Yes. You can retroactively permit an illegally built structure. However, it must be brought up to current code which can be expensive depending on where and how it was built. A lot of times energy efficiency is the hard part. It’s easier to bring a building to code when starting from scratch.

If you’re interested in taking advantage of these new regulations, you can start with downloading our free tool kit.

Plan, hire, and manage your ADU project with Maxable.

At Maxable, we believe that building an ADU should be fun and exciting. You shouldn’t have to be the one to deal with confusing obstacles like permitting snafus or ever-changing regulations. We’ll be by your side every step of the way and connect you to experienced designers and general contractors in your area to make sure your project goes as smoothly as possible.

Leave the headaches to us! Check your address and see what Maxable can do for your home during an ADU Planning Call.