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  • Writer's pictureCRAIKER

ADUs and Multi-family

AB 68 Accessory Dwelling Units (ADUs) conjure up images of single-family homeowners with an underused back yard or aging Baby Boomers who want the retirement income of a rental home on their property. But as of January 1, 2020, new State laws require municipalities to be more flexible in allowing ADUs, including game-changing ADUs on multifamily properties.

Owners of multifamily buildings are always balancing operating costs and revenue. They may have older buildings with costly maintenance or want to build new apartments, but can’t quite get them to pencil out due to high construction costs. Multifamily ADUs (MADUs) can help solve these problems while simultaneously fighting California’s overpriced housing market.

The process is comparatively quick and easy, circumventing the difficult planning department hoops typical of multifamily projects. I liken it to getting a Community Chest card in Monopoly that gives you another house on properties that already have hotels on them. This is a true game-changer.

Local agencies scrambled at the end of 2019 to update their local ordinances to conform with the new State laws. A handful of aggressive planning departments already had ordinances that allowed more than the new laws (larger or taller ADUs, for example), but many others were dragged kicking and screaming into this brave new world.

Cities are still struggling to align their ordinances with State law, so check the current ordinance where you’re working. But here are some of the most impactful multifamily aspects of the new laws:

Junior ADUs (JADUs):

  • Multiple JADUs can be created within an existing multifamily building. We were working on a rehab of an 8-unit 1940’s apartment building when the new laws were enacted, allowing us to carve two more units out of unused mechanical and storage space.

  • The number of JADUs is limited to 25% of the original number of dwelling units.

  • JADUs can be carved out of storage rooms, boiler rooms, passageways, attics, basements, or garages (but not existing living space) as long as the new spaces meet building code requirements.

Location and Size:

  • When there’s an existing multifamily building on a lot, up to two detached MADUs are allowed. These can go just four feet from the rear and side property lines, even if the base zoning requires larger setbacks.

  • MADUs can be up to 850 SF for a studio or one-bedroom units, or 1,000 SF for two-bedroom or larger units. Some cities, like Berkeley, allow MADUs to be 1,200 SF.

  • Any detached ADU is limited to a 16-foot height. This is in response to concerns that two-story buildings four feet from back yard property lines create a privacy problem for neighbors, and that they are more likely to block views on hillside locations.

  • Lot size or coverage is not a limitation.

Parking and Emergency Access:

• New MADUs are not required to provide parking as long as any of the following is true: 

  • It’s within half a mile of public transit (even just a bus stop).

  • It’s in a significant historic district. It’s within a proposed or existing primary residence or accessory structure.

  • On-street parking permits are required but not offered to the occupant of ADUs.

  • It’s within a block of a permanent car share vehicle location.

• Accessible parking space requirements of the California Building Code (CBC) Chapter 11A still apply, so check with your local agency and the CBC.

• When demolishing or converting a garage, carport, or covered parking structure, replacement parking is not required. The only exception is required accessible parking.

• Cities have different safety requirements for emergency access, especially for narrow hillside streets and certain fire zones. Such restrictions on any type of ADU are allowed by State law.


  • MADUs “shall be considered ministerially without discretionary review or a hearing” and are to be approved within 60 days of a complete application being submitted. So an agency can’t slow you down with a public hearing or design review process.

  • When you’re proposing a new multifamily building AND a detached MADU, the reviewing agency can follow their regular process and requirements for the main building, but then has to abide by the 60-day rule for the MADU. So MADUs are definitely faster if you’ve already got a building in place.

  • For the few cities that already had a MADU ordinance as of July 1, 2018, State law allows imposition of “standards, including, but not limited to, design, development, and historic standards” on MADUs, but not minimum lot size standards. It’s unclear whether these additional requirements allow agencies to take more than 60 days for their review, so bring this up in your first discussions with a Planner.


  • Unfortunately, encouraging better accessible design in MADUs didn’t make it into the new laws. But we architects need to think about the aging of the Baby Boom population and take every opportunity to create level entrances, accessible bathrooms and kitchens, and other amenities that we’ll all need more more of in the upcoming years. Do future residents a favor while also helping your clients to future-proof their MADUs. My mantra: Make your Granny Flats actually work for Granny!

Multifamily ADUs are a new tool that helps us add value to projects and make a dent in the housing crisis. We should take any opportunity to build these small-scale accessible apartments. They will make our neighborhoods more diverse, more affordable, and more interesting.

Now go forth and multiply.

On January 1, 2020, it will become easier to build Accessory Dwelling Units in California, thanks to a package of new bills. These bills invalidate local ADU ordinances across the state and replace them with state-mandated rules. Here are some highlights of California’s new ADU law: Reduced Costs and Burdens for Developing ADUs Cities must approve ADU applications within 60 days, without a hearing or discretionary review. For ADUs permitted by 2025, cities cannot require the owner to live at the property. Cities cannot charge any impact fees for ADUs under 750 sqft; fees for larger ADUs are limited. Homeowners associations must allow the construction of ADUs. ADUs can be developed at the same time as a primary unit, under most of the same rules. A city must delay code enforcement against an existing unlawful ADU to allow it to be legalized. For areas where development is county-controlled, all of these same rules apply to counties. ADUs Subject to Automatic Approval — No Local Limits Cities must permit certain categories of ADU without applying any local development standards (e.g., limits on lot size, unit size, parking, height, setbacks, landscaping, or aesthetics), if proposed on a lot developed with one single-family home. ADUs eligible for this automatic approval include: An ADU converted from existing space in the home or another structure (e.g., a garage), so long as the ADU can be accessed from the exterior and has setbacks sufficient for fire safety. A new detached ADU that is no larger than 800 sqft, has a maximum height of 16 feet, and has rear and side setbacks of 4 feet. Both of the above options (creating two ADUs), if the converted ADU is smaller than 500 sqft. ADUs Subject to Ministerial Approval — Minimal Local Limits Even if not subject to automatic approval, a city generally must approve any attached or detached ADU under 1,200 sqft unless the city adopts a new ADU ordinance setting local development standards for ADUs. If a city adopts such an ordinance, it must abide by the following restrictions: No minimum lot size requirements. No maximum unit size limit under 850 sqft (or 1,000 sqft for a two-bedroom ADU). No required replacement parking when a parking garage is converted into an ADU. No required parking for an ADU created through the conversion of existing space or located within a half-mile walking distance of a bus stop or transit station. If the city imposes a floor area ratio limitation or similar rule, the limit must be designed to allow the development of at least one 800 sqft attached or detached ADU on every lot. Adding Units to Multifamily Properties For the first time, the new laws allow units to be added to multifamily buildings. Cities must permit these types of units in multifamily buildings without applying any local development standards: New units within the existing non-living space of a building (e.g., storage rooms, basements, or garages). At least one unit and up to ¼ of the existing unit count may be created this way. Two new homes on the same lot as the multifamily building but detached from it, with 4-foot side and rear setbacks and a 16-foot maximum height.

Assembly Bill 1485, authored by Assembly member Buffy Wicks (D-Oakland), adds an additional class of projects that qualify for streamlined project approval and clarifies existing law under Senate Bill 35 (California Government Code Section 65913.4). SB 35, which was adopted in 2017, required local entities to approve certain housing projects through a ministerial approval process within specified timeframes, removed the requirement for analysis under the California Environmental Quality Act (CEQA), and removed the requirement for Conditional Use Authorization or other similar discretionary entitlements granted by a Planning Commission. SB 35 projects must also commit to paying prevailing wages to construction workers.

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