Everything You Need to Know About ADU Requirements in California

You’ve spent your entire life in California. Your whole family lives here. And now, with your own family growing, your parents aging, and your children growing up, you want to find housing that works for the whole family.

Unfortunately, if you’re like many families in California, the current housing market renders that goal almost impossible.

The good news? California is pursuing a better alternative. The state has passed a huge collection of new ADU-friendly laws designed to encourage homeowners to pursue ADUs as a valid housing option. So many, in fact, that it’s hard to keep track of the current status of the law.

Here, we’re doing a review of the most important ADU requirements in California, including some of the recent laws that change the way California approaches ADUs and what they mean for your family.

What are ADUs?

Accessory dwelling units, or ADUs, are self-contained residential units on the lot of a pre-existing single-family home. You may have heard of them under different names, including:

  • Accessory apartment
  • Accessory suite
  • Accessory unit
  • Backyard cottage
  • Basement apartment
  • Carriage house
  • Dawdy house (among the Amish)
  • Garden cottage
  • Granny flat
  • Home within a home
  • In-law suite
  • Laneway house
  • Mother-in-law suite
  • Multigenerational homes
  • Secondary dwelling unit
  • Tiny house (sometimes–not all tiny houses are ADUs)

ADUs are sometimes called tiny houses, but not all tiny houses are ADUs. That’s because ADUs must have foundations and utility hookups, and while they can be freestanding, they can also be attached to the main house or fully integrated into the home.

There are four types of ADUs:

  1. Detached
  2. Attached
  3. Interior conversion
  4. Garage conversion

Detached ADUs are the most independent of the four, with a fully separate foundation, utility hookup, and sometimes even their own entrance. On the other hand, interior conversions (like basement apartments) are part of the pre-existing home, but they serve as functional, fully independent units within the home.

Even if the unit is fully detached from the primary residence, ADUs are still considered part of the primary lot. However, the owner may choose to rent the property to tenants, relatives, or friends. Essentially, you have a second home within your home.

The Solution to the Affordable Housing Crisis

This makes ADUs a great solution to California’s affordable housing crisis.

The housing crisis is the price of California’s economic boom. Nearly 30 years of churning growth kept out the type of housing developments that are now critical to meeting demand.

The median home price now tops $600,000, more than twice the national average. Housing prices have skyrocketed by 75% in the last five years in San Francisco, Los Angeles, San Jose, and San Diego, four of the hottest housing markets.

Even those who earn six figures, a good income anywhere else in the country, have to commute an hour or more to affordable housing each day.

ADUs offer the perfect solution for families, whether you need to live closer to your job, get your young family off on the right foot, support your adult kids, or take care of an elderly or disabled relative. Instead of fighting with millions of other California residents for the few remaining affordable units, you can find the perfect space right in your own backyard.

ADU Requirements in California

All across the state, legislators at all levels are recognizing the rising costs of California’s housing crisis.

The problem itself is straightforward: there isn’t enough housing supply to meet demand. But the fallout is more complicated. The lack of affordable housing is severely restricting growth, with significant environmental and economic damage as families choose between losing hours each day to commuting or seeking opportunities outside the state.

New ADU Bills

To that end, California passed a wave of bills in the last several years to remove barriers to entry for ADUs, protect tenants, and actively encourage ADU building. A few years ago, it was almost impossible to build an ADU on your property.

Now, the state is opening the door for a flood of change, encouraging the housing market to rethink the way it views traditional property.

That said, with all the new bills currently on the books or recently added to California law, it can be hard to keep track of the law as it stands. Here are a few essential laws to know.

SB 13 (Wieckowski) – Owner-Occupancy Prohibitions and Fee Limitations

Senate bill 13, authored by Senator Bob Wieckowski, is the heaviest of the recent additions. The good news is that there are several components of SB 13 that make it easier for California homeowners to build ADUs.

The Planning and Zoning Law authorizes local agencies to provide for the creation of ADUs in single- and multi-family residences within certain requirements, such as the ADU being attached to or located within the proposed residence. SB 13 allows homeowners to build ADUs in areas zoned for single- and multi-family residential use while revising the requirements for approval.

In addition, owners were previously required to replace parking spaces on their property if they were converting or demolishing their garage, carport, or parking space. SB 13 eliminates this requirement. You will be required to add a parking space if you are more than half a mile from public transportation, but your driveway can satisfy this requirement.

The bill also eliminates the old owner occupancy rule, which demanded owner occupancy of the ADU for at least five years. In the meantime, SB 13 puts pressure on city permitting offices to expedite approvals, slicing approval time down to 60 days compared to the previous 120-day waiting period.

Last but not least, SB 13 waives your ADU building fees if the ADU is less than 750 square feet. If the unit is more than 750 square feet, fees will be structured in a graduated scale proportional to square footage.

SB 1226 (Bates) – Building Standards: Building Permits

Senate bill 1226, authored by Senator Patricia Bates, was signed into law in 2018. It was sponsored by the city of Encinitas and Mayor Catherine S. Blakespear, but the bill is intended to reduce ADU barriers across the state.

The bill directs the California Building Standards Commission to adopt a standard clarifying the role of local governments to permit an existing ADU based on the year the ADU was constructed.

If, for example, an ADU was constructed in 1995, the instructor could use the 1995 building code to issue a permit. This would allow unpermitted ADUs to be brought up to code and made available on the housing market.

The goal in Encinitas was to bring pre-existing ADUs out of the shadows and up to code. This was done to complement an Encinitas rule which states that ADU owners must offer rental terms of at least 30 days, preventing homeowners from using ADUs as tourist rentals to skirt public safety regulations at the risk of long-term renters. However, most cities don’t have structure conversion guidelines, which requires builders to take a specialised approach.

SB 330 (Skinner) – Housing Crisis Act of 2019

Senate bill 330, the Housing Crisis Act of 2019, is one of the most important and extensive new laws affecting large-scale housing developments.

Among the key procedural changes introduced by the bill, a few stand out:

  • Preliminary application protections
  • Application completeness streamlining
  • Fees and exactions limitations
  • Hearing limitations
  • Downzoning prohibitions

The application protections, for example, limit a jurisdiction’s ability to change zoning and development standards applicable to a project after the project’s preliminary application is submitted.

In addition, the Act specifies what constitutes a “preliminary application”. A jurisdiction has one chance to identify incomplete items in an application and may not request new information for submission if the information was not included on the original list of missing items.

This ties into fees and exactions limits. Under the new law, jurisdiction cannot increase fees during the application period, but fees can go up if the regulation establishing the fee calls for fee increases over time.

The Act also limits the number of hearings that can be conducted on a proposed housing project. If the proposal complies with the objective general plan and zoning laws in effect at the time the application is marked complete, the city may not hold more than five hearings on the proposal.

Downzoning prohibitions prevent jurisdiction from enacting housing policies that would “lessen the intensity of housing”. It also prohibits any moratoriums or similar restrictions on housing developments, prohibits subjective design standards established after January 1, 2020, and prohibits limits on the number of permits which may be issued in a non-agricultural jurisdiction.

AB 1763 (Chiu) – Density Bonuses for 100 Percent Affordable Projects

Building off of SB 330 is Assembly Bill 1763, which works to combat density restrictions in certain areas that have previously halted ADU projects.

The pre-existing Density Bonus Law requires a city or county to provide a density bonus to a housing development to incentivize construction of low-income housing. AB 1763 expands the density bonus to include developers who agree to construct a housing development in which 100% of the available units are for lower-income households.

However, the bill also states that a housing development may qualify for a density bonus if up to 20% of its units are for middle-income households. The remaining 80% of units must be designated for low-income housing, except for manager units where appropriate, and the units must be priced appropriately based on their designation.

A housing unit that meets these criteria will receive four additional concessions under the Density Bonus Law and a height increase of up to three stories if the development is located within half a mile of a major transit stop.

Generally, housing developments can receive a bonus of up to 80%, but the development is exempted from maximum density controls if it is located within half a mile of a major transit stop.

AB 1485 (Wicks) – Amendments to SB 35’s Streamlined Ministerial Approval Process

Assembly bill 1485 offers an in-depth clarification of several points contained in the 2017 Senate bill 35.

SB 35 allowed qualifying housing and housing-rich mixed-use projects to qualify for streamlined ministerial approval with CEQA exemption, provided that the project met local zoning, design, and subdivision review regulations.

AB 1485 amended a few key points of SB 35:

  • Moderate-income options
  • Approval expiration dates
  • Calculating two-thirds mixed-use projects
  • Subsequent permits
  • Standards of review and consistency with other laws
  • Clarification of Housing Accountability Act coverage

AB 1485 expanded eligibility for SB 35 to Bay Area projects which provide 20% of their units to moderate-income households (i.e. less than 120% of area median income).

It also clarified the three-year approval expiration dates under SB 35. In cases of litigation, the three-year expiration of SB 35 expires three years after the final judgment upholding approval of the project. The approval remains valid as long as vertical construction is underway and in progress.

In addition, it clarified the calculation used to determine if a project qualified as mixed-use under SB 35. The new law states that a project qualifies as mixed-use under SB 35 if it consists of two-thirds residential spaces, excluding underground spaces such as basements and parking garages.

As for permitting, the bill clarifies that local governments must issue subsequent permitting (i.e. grading, final maps, demolition, building permits) without delay, as long as the subsequent permit applications comply with the previously approved SB 35 permit.

Under the new law, the standard determining whether a project qualifies under SB 35 is deferential to the applicant. So long as there is evidence that would allow a reasonable person to conclude that the project complies with SB 35, the project qualifies under SB 35.

Finally, the law states plainly that any properties qualifying under SB 35 are entitled to protections under the Housing Accountability Act.

AB 68 (Ting) / AB 881 (Bloom) – Processing Timelines, Ordinance Prohibitions and Triplexes

Technically, Assembly bill 68 and Assembly bill 881 are two different laws, but they declare many of the same things. For our purposes, we will review both laws together.

Essentially, the laws require that a local agency must either approve or deny an ADU project within 60 days of receiving the complete proposal on a ministerial (i.e. CEQA-exempt) basis. In addition, local agencies cannot adopt ordinances that:

  • Set certain maximum ADU dimensions
  • Impose minimum lot size requirements
  • Require replacement of parking when previous parking is demolished or converted

In these respects, the laws have much in common with SB 13.

What’s significant about these laws is that they allow for ADUs and junior ADUs where certain setback, access, and other criteria are met. This is known as the tripelex-ation of single family housing. This is the most exciting element of these laws–you’re now allowed to have an ADU and JADU (a small unit constructed from a bedroom) on your primary dwelling.

The laws also build on options, allowing homeowners to build ADUs in boiler rooms, storage rooms, and similar areas in multi-family housing where building standards are met.

Plus, AB 881 creates much more lenient setback requirements, which were previously a huge obstacle for many homeowners.

AB 670 (Friedman) – Common Interest Developments: Accessory Dwelling Units

Before Assembly bill 670, homeowners’ associations (HOAs) were the frequent enemy of ADUs and homeowners who wanted to build them. This was a huge barrier to ADUs, considering that HOAs were one of the only governing bodies with the authority to overwrite state laws.

This left millions of eligible homes unable to build ADUs, not because of the lot, but because HOAs nixed the idea.

Now, under AB 670, HOAs are no longer able to bar ADUs in single-family homes. While HOAs are still able to establish guidelines, such as unit sizes and rental terms, they are no longer able to ban construction occurring on or adjacent to a member’s property. They cannot “unreasonably restrict” construction either, barring you without directly “barring” you.

In addition, the AB 670 amnesty program addresses the issue of illegally built ADUs. If you built an ADU on your property without the required permits or inspections, you now have five years to bring the ADU up to code, provided that there are not any health and safety issues on the property which must be addressed immediately.

AB 671 (Friedman) – Accessory Dwelling Units: Incentives

A related law, Assembly Bill 671, further encourages homeowners to build ADUs by lowering costs through government incentives. Existing laws require local governments to provide for the creation of ADUs on single-family and multi-family lots, but this law encourages them to go further.

Under the law, local governments are now required to include housing elements plans in their General Plans which incentivize and promote the creation of ADUs. The Department of Housing and Community Development is required to generate a list of existing state grants and other financial incentives for expenses attached to building and maintaining ADUs.

That list will be made available on the Department’s website by December 31, 2020.

AB 587 (Friedman) – Separate Conveyances

Traditionally, ADUs were considered part of the original lot and could not be sold separately from the main lot. Assembly Bill 587 changes that, improving the options of those in dire need of low-income housing.

Under the new law, local agencies may now allow ADUs to be sold or conveyed separately from the primary lot, provided that certain conditions are met. These generally apply to ADUs built by qualified nonprofit corporations, and qualified buyers must use the ADU as their primary residence.

In short, if the property is owned by a nonprofit for the purpose of renovating or rehabilitating single- or multi-family properties for sale to low-income families, then the ADU is eligible to be sold as a separate property to a qualified buyer, i.e. a buyer of low or moderate income.

This bill is a huge deal for low-income families, as it significantly increases the availability of independent housing units. Where before, families would have had to rent from the primary homeowner or buy the primary residence in order to use the ADU, some ADUs will now be available as independent housing from the primary unit.

Essentially, you now have two properties where you used to have just one, and one of the properties is affordable to average families.

ADU Requirements by City

So far, we’ve reviewed laws covering the whole state. But there are also dozens of local laws on the books between various cities and counties. We work in 22 different cities across California, and offer a review of the current laws on the books in each city.

Historically, local ordinances were often the last barrier of entry for interested homeowners, despite the fact that California law has always allowed for the creation of ADUs. While three 2016 laws made it easier to build ADUs, and the laws reviewed here have significantly improved the process, there is still a lot of variation between cities.

As such, if you are interested in building an ADU, it’s best to look at the laws in your city to get the final word on your eligibility.

Let Us Help Build the ADU of Your Dreams

We know that navigating ADU requirements in California is not easy, even with all the new laws intended to simplify the process for homeowners. That’s why we’re here–to provide the support you need to build the family home you’ve been dreaming of.

If you need somewhere to get started, make sure to check out our Frequently Asked Questions page. And if you need to speak with an ADU specialist about your options, get in touch today!

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