Navigating the regulations that affect new ADU projects can be daunting. Each state, county, city or town has their own rules and regulations that affect these projects. However, some states are passing state-wide rules to aim to unify some of the restrictions and make ADU development easier. California is one of the states leading this charge as they aim to promote ADUs as an important part of addressing housing affordability challenges.
With the goal of making ADUs easier to build, California has been passing some great laws that have drastically changed the ADU rules. There are some big changes even from last year. In the article below we will discuss some of the updated rules. But first, let’s start with the basics.
What is an ADU?
ADU is an acronym for Accessory Dwelling Unit. Often called other names like casita, laneway suite, garden suite, granny flat, or even guest house, ADUs are secondary homes built on a property, which are accessory to the primary structure. Unlike tiny houses on wheels, ADUs are full houses and include permanent foundations, separate entrances from the main house, fully functional kitchens, full bathroom, space for sleeping (either a bedroom or space for a bed if the unit is a studio), plus full utilities (water, sewer, and electricity).
ADUs are typically built as rental units, houses for extended families, or homes for downsizing and aging-in-place. In many places they can also be used as short-term rentals like for AirBnB or VRBO, although some towns and cities prohibit this use as they want ADUs to be used as permanent housing.
California Regulation Changes for 2024
Where there once was a tapestry of different rules and regulations across the state, California has been working on passing ADU laws that are applied statewide. Government officials have seen the challenges of having so many different rules and restrictions, thus they have been working to pass laws that override local restrictions that were used to prohibit or significantly hinder the ability for some homeowners to add ADUs to their properties. Because ADUs provide a lot of benefits to both individual property owners as well as society at large, passing statewide regulations that are easy to meet is helping people build enough ADUs to significantly increase the housing supply across the state.
Owner Occupancy on the Property
Owners are no longer required to live on the property if they want to build an ADU and rent it out according to AB 976. Property owners can now build ADUs and rent out both the main house and the new ADU. California has removed this requirement statewide, meaning no local jurisdiction can make this a requirement. This is a win for those looking to add ADUs to properties they currently own but are renting out. We believe ADUs are great investment opportunities and this doubles down on that belief.
ADUs can be sold separately as Condos
We absolutely love this change and think it is a true game changer for ADUs. It is something we hope spreads nation-wide as a way to make more affordable starter homes available for purchase.
Basically, it is now possible to build a new ADU on a property, and then condoize all of the homes on the property to be able to sell them separately. Meaning, you can now develop ADUs as a for-sale product rather than just as a rental unit. This is great if you want to build an ADU as an investment but want to get your money out of the project relatively quickly.
In markets where housing prices are quite high, you could see situations where you may build an ADU for say $300,000, condoize the property, and then sell off the ADU for say $450,000. In just a year or two you could see a 50% return on your investment. Plus you are creating a home that can be purchased for a very reasonable cost compared to many homes on the market.
ADU Types that are now allowed in California
All residential properties are eligible to add an ADU. And depending on the size of the property you could build up to 3 ADUs on your property - one Junior ADU (JADU), one attached ADU, and one Detached ADU (DADU). You can also convert existing structures like garages into ADUs.
ADU Size regulations
There are different maximum size limitations based on the property and layout of the ADU. In all cases you should be able to build an ADU up to 800sf. Individual jurisdictions can’t limit ADUs to below that size but can pass local laws increasing the maximum size an ADU can be. The state has passed laws that if no maximum size is defined then the maximum size is automatically set at 1,200sf for detached ADUs. If you are doing an attached ADU you can build up to 50% of the floor area of the main house or 800sf, whichever is larger.
Furthermore, if you are converting an existing structure you don’t have to abide by ADU size limitations as long as you aren’t expanding the size of the structure. If you stay within the existing footprint you can have an ADU of any side. This is great news if you are converting a large garage, basement, or other existing space into an ADU
Property Setbacks for ADUs
Most properties have setback requirements for buildings that prevent you from building right up to the property lines. I am very much against property setbacks as they prevent us from building some of the best housing types, like attached row houses. Side setbacks especially should be illegal nation-wide. But that is a battle for another day.
For ADUs in California side and rear setbacks are set at 4’ unless a local jurisdiction passes a law reducing that. Places like San Diego have stated that there is a 0ft side and rear setback for ADUs!
The front setbacks are a bit more flexible and can still be set by each jurisdiction as long as it doesn’t hinder the property owner’s ability to build an ADU up to 800sf.
ADU Height Limits
Height limits get a bit more complicated as it depends on location of the property, existing structures, and the type of ADU. The following rules apply:
16 ft height limit is the minimum for every ADU in California under any circumstance. Local jurisdictions can’t enforce a lower height limit. This most likely leads to a single story ADU although we have found some creative workarounds to get two-story ADUs within a 16’ height limit. Curious? Contact us for more information.
18 ft heights are allowed if an ADU is within 1/2 mile walking distance from public transit or if the property already has a two story tall multi-family dwelling. 18’ tall ADUs can definitely be a two story structure.
25 ft height limits are imposed if the ADU is going to be attached to the main residence. Even if the main house is taller, the ADU can only be 25’ tall.
Parking Requirements for ADUs
This is another area where we disagree with many of the regulations. Under no circumstances should parking be required on any property. It should be up to the property owner to decide if they want to build parking. Parking minimums are the dumbest laws and directly lead to more expensive housing and terrible environmental impacts. Parking requirements should be abolished nation-wide.
Alas, here are the rules:
Off-street parking is required for ADUs in most circumstances.
Exceptions:
If an ADU is within 1/2 mile walking distance from public transit
If the ADU is within a historical district
If the ADU is a conversion of existing space (like a basement or garage)
If the ADU is located within one block of a car-share vehicle
On street parking permits are required in your neighborhood but aren’t offered to the occupant of the ADU
If you are converting a garage into an ADU, you are not required to replace the lost parking space.
CalHFA ADU Grant Availability
The CalHFA ADU Grant provided up to $40,000 towards the soft costs of building an ADU (soft costs are things like design, permitting fees, etc.). It was so popular that the latest allotment of $25 million committed to the program was claimed in just a few days. Thus no more funds are available as of the start of 2024.
Considering the popularity of the program and the continued need for new housing there is a good chance that it will be refunded in the near future.
Fire Sprinkler Requirements for ADUs
Fire sprinklers aren’t required except in a few circumstances. If they are required in the main house then they are also required in the ADU. Also, if the ADU is built far enough away from road or driveway access a sprinkler system may be required. This is due to access to the structure by the fire department and access for their trucks combined with length of fire hoses. If your ADU will be located more than say 150’ away from the street you may need to install sprinklers. Contact your local building department to verify the specifics of your project.
ADUs are now allowed on multi-family properties
All multi-family properties are now eligible to have ADUs. In fact, you can add at least one ADU by converting existing space in the building and you can add up to two additional detached ADUs. It gets even better. If the multi-family building has more than 8 units, you can add up to 25% of the number of units in the existing building. Example: if you have a 12 unit apartment building you can add up to 3 ADus (25% of the existing units).
Solar Panel Requirements for ADUs
When building a detached ADU it is required that you have solar panels on either the ADU or the main house. However, there are some exceptions for prefab ADUs or Modular ADUs. There aren’t solar requirements for basement ADUs, or JADUs.
Ready to start your ADU Project?
At Modern ADU Plans are here to help you achieve your goals and have a successful ADU project. Head over to our ADU store to find a beautiful ADU that meets your needs, or contact us if you are considering a custom designed ADU solution. We also offer some free resources on this website and consultations if you want to meet with an ADU design expert to ask questions.
