New ADU Laws in 2023
California’s legislature passed 3 different bills related to ADUs in 2022
There are over a dozen rule changes in these cleanup bills!
This article will cover some of the changes in AB 2221, AB 916, AB 561, and SB 897 including:
2 story ADUs will be popping up around the entire state
new government-backed finance programs
no more front setbacks for statewide exemption ADUs
stricter 60 day limits on all permitting agencies
over a dozen other rule changes that make California ADU law better than ever in 2023
If you’re just starting your ADU research, you should first read about the laws that were passed in 2017 and 2019 which are well-summarized in the HCD’s ADU handbook (last updated July 2022).
This article will cover my first read and broad interpretation of changes that are in these 3 new laws passed in 2022, set to go into effect in January 2023.
The way these rules get interpreted and enforced in each jurisdiction always varies a bit from my interpretation so please write to hello@how-to-adu.com about any discrepancies you find and always talk to your local planning department about your specific project.
What is the new ADU law in California?
2 Story ADUs
In the past, the state law allowed local jurisdictions to impose a maximum height of 16 feet on Accessory Dwelling Units.
This effectively prevented most people in the jurisdictions from building 2 story ADUs (because you need a foundation, a bit of room between the first and second story, and a roof which put you over 16 feet).
The amendments in AB2221 and SB897 create new limits on what city or county ordinances can say about the maximum height of an ADU.
There are now 4 categories with different height restrictions:
A height of 16 feet for a detached accessory dwelling unit on a lot with an existing or proposed single family or multifamily dwelling unit.
A height of 18 feet for a detached accessory dwelling unit on a lot with an existing or proposed single family or multifamily dwelling unit that is within one-half of one mile walking distance of a major transit stop or a high-quality transit corridor, as those terms are defined in Section 21155 of the Public Resources Code. A local agency shall also allow an additional two feet in height to accommodate a roof pitch on the accessory dwelling unit that is aligned with the roof pitch of the primary dwelling unit.
A height of 18 feet for a detached accessory dwelling unit on a lot with an existing or proposed multifamily, multistory dwelling.
A height of 25 feet or the height limitation in the local zoning ordinance that applies to the primary dwelling, whichever is lower, for an accessory dwelling unit that is attached to a primary dwelling. This clause shall not require a local agency to allow an accessory dwelling unit to exceed two stories.
My Interpretation of the Height Rules In Plain English:
Attached ADU height limit: If you are building an ADU attached to the primary house, the city has to allow either 25 feet or the same height that is allowed in the underlying zoning code, whichever is lower.
Multi-family multi-story height limit: If you are building on a property where you have an existing or proposed multi-family, multi-story dwelling, the city has to allow you to build up to 18 feet.
ADUs near transit height limit: If you are building a detached ADU within half a mile walking distance of a very good transit stop (like a bus comes through every 15 minutes or it meets some other high standards) then the city has to allow you to build up to 18 feet. Furthermore, the city needs to allow an additional 2 feet in height to accommodate a roof pitch on the ADU that is aligned with the roof pitch of the primary.
All the other ADUs: If you don’t fit into one of the above categories, the city has to allow you to build up to 16 feet.
Broadly speaking, the intent of this law is to allow you to build 2 story ADUs if you’re in one of those categories (attached to the primary, on a multi-family lot, or near good mass transit). If you have a lot in one of those categories and feel like the city is giving you the runaround, you should contact the HCD.
Common questions about the height rules:
Does building above a garage count as attached?
My read is that if you are building above a garage attached to the primary, then it counts as attached. If you are building on top of a detached garage, I don’t think the city will hold back - I imagine they could try to apply the 16 foot height limit.
Does this change the maximum size of an ADU?
My read is that it does not directly affect the maximum size of an ADU. If your city says a 2+ bedroom has to be smaller than 1000 sq ft of habitable living space, building 2 stories does not mean you’d get 2000 sq ft. You could do 500 and 500 or 600 and 400 though.
Having said that, if the limit on your ADU is a percentage based ordinance like an open space requirement, then a 2 story ADU may practically allow you to build more habitable space.
For example, let’s say that a homeowner lives in a city says that ADUs can be 1200 sq ft but there is a 50% open space requirement on all lots. A homeowner might do the math and find out that they can only build a 900 sq ft footprint before hitting their open space maximum. In the past they would be restricted to a 1 story 900 sq ft ADU. In the future, they could imagine building a 2 story ADU that is 900 sq ft on the first floor and 300 sq ft on the 2nd floor. Or 600 and 600.
What is a high quality transit corridor and what is a major transit stop?
“For purposes of this section, a high-quality transit corridor means a corridor with fixed route bus service with service intervals no longer than 15 minutes during peak commute hours.“
“A major transit stop is as defined in Section 21064.3, except that, for purposes of this section, it also includes major transit stops that are included in the applicable regional transportation plan“
“Major transit stop” means a site containing any of the following:
(a) An existing rail or bus rapid transit station.
(b) A ferry terminal served by either a bus or rail transit service.
(c) The intersection of two or more major bus routes with a frequency of service interval of 15 minutes or less during the morning and afternoon peak commute periods.
I haven’t found a definition for “Peak commute hours” in the statutes. I think these are defined at the local level in some jurisdictions. And otherwise, the MTC (Metropolitan Transportation Commission) puts it at 6-10am and 3-7pm (similar to the carpool lane rules).
If you’re pulling data statewide, here’s a good California transit stop data resource on GitHub using the above definitions in its methodology (as of September 26, 2022).
Other 2023 California ADU Laws
While 2 story ADUs are the big attention-grabbing headline change, there are actually over a dozen changes in SB 897 and AB 2221.
These are both cleanup bills that tweak language across the entire ADU section of the government code.
It’s tough to know exactly how every jurisdiction will interpret and enforce each rule, but here is a laundry list in plain English based on my notes. Keep in mind your local planning department is the real authority on how these rules will be implemented in your town, and the HCD is the state authority that can consult the local agencies if they are out of compliance with the state code.
List of ADU Rules included in SB 897 and AB 2221:
60 day rule
The rule that says local agencies have 60 days to act on your permit application have been clarified in several ways to make it much clearer what happens. Enforcement will still be a mystery from my perspective, but:
“local agencies” changed to “permitting agencies” so it includes water districts, special corporations, and other permitting bodies that were previously playing coy “Permitting agency” means any entity that is involved in the review of a permit for an accessory dwelling unit or junior accessory dwelling unit and for which there is no substitute, including, but not limited to, applicable planning departments, building departments, utilities, and special districts.
“act on” has changed to “approve or deny” so the agency has to say yes or no, it can’t just say it has started reviewing
when an agency denies it has to give a full list of all the objective reasons why it denied the project at the same time
Front setback clarity
Front setbacks have been added explicitly to the list of local zoning restrictions which cannot preclude the construction of an ADU under 800 sq ft within 4 foot side and rear yard setbacks (and under the legal height restriction).
Objective standards
The definition of objective standards has been added to statute. “Objective standards” means standards that involve no personal or subjective judgment by a public official and are uniformly verifiable by reference to an external and uniform benchmark or criterion available and knowable by both the development applicant or proponent and the public official prior to submittal.
And a laundry list of the other changes that we’ll be exploring more in the future:
Prevents cities/counties from denying a permit due to the correction of non-conforming zoning conditions, building code violations, or unpermitted structures
Local agencies have to issue demolition permits for detached garages to be replaced with ADU
Prohibits requirements to provide written notice or post a placard for the demo of the garage
Construction of ADUs doesn't trigger a "Group R" occupancy change
Construction of ADUs can’t trigger the requirement that fire sprinklers be installed in the existing primary dwelling
Broader, simpler "no parking requirements"
When the city says no, they have to say why - full list that can be remedied
JADUs without a bathroom need access to the house - was this something people were doing?
Makes it easier to legalize an unpermitted ADU built before 2018
And some funny order stuff
AB 916 - Room Additions
This is a cheeky one. It’s not actually about ADUs.
It says that the city can't require a public hearing to add a bedroom or two, to an existing dwelling unit.
I have a lot of questions about how this will play out because it’s not the same wording as the ADU’s ministerial, non-discretionary process. But the language is still pretty powerful.
Will local jurisdictions allow this to apply to parts of the home that aren’t attached to the primary?
Will local jurisdictions let us use this to convert garages, basements, attics, laundry rooms and other unconditioned spaces into habitable bedrooms?
This could be a sleeper hit.