Can I Build Multiple ADUs?

Yes, you can — courtesy of Assembly Bill 68 (AB-68), ADU (Accessory Dwelling Units) construction in California just became that much simpler. You can now build multiple ADUs on both single- and multi-family lots, as long as your project conforms to the inescapable (yet surprisingly flexible) new regulations.

This post will dissect AB-68’s provisions and answer your most pressing questions about the new bill’s effect on ADU construction in California.

How Many ADUs Can I build? 

Thanks to AB-68, the current state ADU legislation is amended to allow several new configurations for both single- and multi-family lots. Here are your options.

On Single-Family Lots

1 attached, standard sized ADU and one Junior-ADU (JADU). The new ADU and JADU must fit within the footprint of the single-family home or an accessory structure, such as a garage or a shed. The new ADUs cannot expand beyond the floor area of the home or accessory structure by more than 150 ft2, and the expansion should only be made to accommodate an entrance or an exit. The new ADUs must also have exterior access from the primary residence, and any new rear and side setbacks should be wide enough to suffice for fire and safety.

Note that the new JADU must conform to the legislation’s definition of a JADU by meeting the following requirements: 

  • The new JADU is no more than 500 ft2 in floor area.
  • The owner lives in either the JADU or the home where the JADU is located.
  • A deed restriction is recorded with the permitting agency, which forbids selling the JADU separately from the home and restricts future alterations to size and characteristics that don’t meet the current state JADU design requirements.
  • The JADU must be built within the walls of the primary home, have a separate entrance, and an efficiency kitchen. The latter needs to comprise a cooking facility with appliances, a cooktop counter, as well as cabinets for storage.

1 detached, standard sized ADU and one JADU. The new detached ADU must have side and rear setbacks of at least 4 feet, and local governments may restrict the floor area to a maximum of 800ft2 and the height to 16 feet. Check with your building officials to find out the local height and area constraints. If you’re using this option to include a JADU, the latter must conform to the JADU requirements described above.

On Multi-Family Lots

Multiple accessory dwelling units within non-liveable spaces of the primary multi-family residence. These spaces may include storage rooms, boiler rooms, passageways, attics, basements, and garages — as long as they comply with the state’s building standards for dwellings. You can convert such a space into at least one ADU in a multi-family dwelling unit, and use up to 25% of a building’s multi-family units for ADU conversions.

2 detached, standard-sized ADU on a lot with an existing multi-family residence. The new ADUs must have side and rear setbacks of at least 4 feet, and their height cannot exceed 16 feet.

Design Everest’s team of engineers would be happy to guide you through the new legislation surrounding ADUs. If you’d like to learn more, please contact us at (877) 675-9828 and we will provide you a FREE consultation..

What Size ADU Can I build? 

The maximum size of your ADUs will vary based on your location, so it’s always best to check with your building officials before planning anything. That said, locally adopted ordinances must allow an ADU with a floor area of at least 800ft2, or 1,000ft2 if the unit includes 2 bedrooms. Your local government must also allow a maximum height of 16 feet, and cannot require side and rear setbacks wider than 4 feet.

If you’re including a JADU, the new unit cannot exceed a floor area of 500ft2, and must be located within the footprint of the primary dwelling.

Other New Regulations That Make It Easier to Build Multiple ADUs 

Apart from explicitly allowing multiple ADUs on single- and multi-family lots, AB-68 also includes several new provisions that will facilitate the construction of more than 1 such unit. For instance, local governments can no longer impose restrictions on ADU lot coverage, open space, floor area ratios, and minimum lot size. Thus, if the ADUs you’re proposing are otherwise compliant with the new bill’s regulations described above, these factors cannot be used to prohibit their construction.

What’s more, any accessory structure — defined as a structure that’s incidental to the primary residence — can be converted into an ADU. These auxiliary buildings include sheds and garages, and can be attached or detached from the home.

To make the permitting process faster, local agencies must now process ADU applications within only 60 days — that’s twice as fast as was required by the previous regulations. The only exception to this new provision falls on applications submitted concurrently for ADUs and for the lot’s primary dwelling. In this situation, building departments may take longer to process the applications.

How Design Everest Can Help

ADUs may be small compared to an average single-family home, but their construction still requires expert planning and guidance. If you’re thinking about building an ADU, our team at Design Everest can walk you through the entire process, from inception to completion. We’ll start by connecting you with an experienced architect in your area. Then, once you’re happy with your ADU’s architectural features, our engineers will furnish civil, structural, and MEP drawings for your project.

Our team will also help streamline your permits and entitlements, and assist with construction administrations during the execution phase. Contact us at (877) 675-9828 and we will provide you a FREE consultation with a quote.

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