Let’s Triplexize California

In October 2019, Governor Gavin Newsom signed three bills into law that effectively legalized no-hassle triplex conversions across the entire state of California.

If you own a single family home and wish you could do something to take on the state’s housing shortage in your own way, the time is now.

The new state laws will break down most barriers to developer one or two new ADUs on your property. Starting at the beginning of next year, you won’t need to worry about:

  • Public hearings.
  • Replacing parking when you convert your garage.
  • Most local zoning requirements.
  • Discretionary approval processes.

Build new, convert your garage, or both!

Cities have limited discretion when it comes to approving an ADU–almost none, in fact.

While state law does authorize a city to implement limitations on accessory dwelling units, state law prescribes another separate set of regulations that cities simply cannot overrule. Those regulations are:

  • 4 foot setbacks
  • 16 foot height limit
  • 800 square feet maximum

That’s it. For years, cities hostile to the Californian dream of affordable housing everywhere have found ways to ban accessory dwelling units using tools such as Floor Area Ratio, replacement parking for garage conversions, elaborate yet vague design requirements, and endless public hearings, just to name the most common.

New state law does away with all those barriers. Most Californian homeowners can now apply for an ADU, garage conversion, or both, over the planning counter. No hearings. No fighting the city. You don’t even need to ask your neighbor for their permission.

The California Renters Legal Advocacy and Education Fund has put together this easy guide to help homeowners get through the process and bring much needed housing to the state without contributing to sprawl.

Is your city putting up a fight?

The state’s housing crisis is 40 years in the making, in part because local cities consistently refuse to allow for more housing. New state laws aimed at making it easier for homeowners to build ADUs are no different and will be fought by Californian cities where housing is most needed, as they have for decades.

If your city is fighting your ADU application, it is very likely to be unlawful behavior. Submit a complaint to CaRLA and we will make sure that your city doesn’t get a free pass from state law.

We’re California’s housing watchdogs, but we depend on your eyes and ears to take action.

How does it work?

Building an ADU or two on your property requires financing, designing, and developing the project. The first step is to figure out how to pay for everything. Most ADUs are financed using existing equity in the property, or the increased equity of the property based on the value of the ADU. Talk to your bank to figure out what options are available to you. 

Next, you will need to figure out where on your property you can fit an ADU. Luckily, this year’s changes to statewide ADU law means that nearly every single-family property in California can fit an ADU. The law specifies two separate sets of rules governing where and how big of an ADU you can develop. The local ordinance provides one path, but you may find that local rules make it difficult to fit an ADU on your property. If this turns out to be the case, you can take advantage of the state rules, which all but guarantee each home one backyard detached ADU, and potentially a small Junior ADU converted from existing space like a garage. As shown in the two drawings below, the allowable build envelope for an ADU can be substantially different from the requirements your local planning ordinance puts on single family homes. These drawings represent the average single family home lot which includes a 15′ front setback, 5′ side setbacks, a 30′ rear yard setback, includes a requirement for a covered parking garage. The state rules free up the back yard for a new detached ADU, subject only to a 4′ rear and side setbacks and a 16 foot height liming, regardless of how your city regulates single family homes. Further, it allows you to convert your garage to a smaller junior ADU, making your single-family property into a triplex!

Isometric view

Overhead view

Design and Build

Once you have figured out where to put your ADU, you’ll need to hire a contractor and architect who can design and build the new homes you’ll be creating. With the increasing popularity of ADUs, businesses are popping up all over the state to provide homeowners with these services. Go with someone with a good reputation who can get the job done, but also pays attention to all the new changes in state law so that you can take advantage of them. CaRLA is assembling a directory of vetted ADU builders in time for the laws to take effect in 2020; sign up for our newsletter to know when we publish it!

In planning your ADU project you will have some choices to make. If you have an existing garage, you can probably convert it to a small ADU without having to build a whole new structure. This can keep costs down and simplify the construction process. If you are adding a new ADU in the backyard, you can choose to buy a pre-fabricated ADU from one of the many businesses around the state that install them. This process involves pouring a foundation and having the new home trucked in and lifted onto the foundation with a crane.

All of these choices can make a difference in the cost and type of ADU you want to develop. Remember that there are lots of options available once the new state law reforms go into effect. Find what suits you and your budget best and go for it!


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Submit your application

Check with your local planning department to learn how to submit the application. If you’ve hired an architect or pre-fabricated ADU supplier, they’ll already know how to do this. This is also where cities will try and avoid their obligations under state law; CaRLA is ready to fight back.

Submitting your application should be quick and painless; if it isn’t, your city is probably breaking the law and we need to know about it. Here are some things to watch out for:

Floor Area Ratio requirements: State law prohibits regulating the overall floor area of a single family property if it would prevent an 800 square foot ADU from being developed.

Distance between the ADU and the existing house: On small lots, these rules can make adding an ADU difficult. You may need to opt for the state approval process, which would bar the city from applying this requirement.

New or replacement parking for the ADU: Cities are prohibited from requiring additional parking for a new ADU in many circumstances. If you convert your garage to an ADU, cities are prohibited from requiring that you replace that parking. Use the savings on an annual bus pass or put it towards an e-bike!

Public hearings or discretionary design review: Nope. State law prohibits these too. While cities can ask that you follow a list of aesthetic design standards, they can’t put your approval to a vote, and those design standards must be objective. Words like “neighborhood character”, “harmonious context”, or even “appropriate massing” might indicate they’re breaking the law.