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Fontana ADU Regulations and Requirements in 2024
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Fontana ADU Regulations and Requirements in 2024

|Dec 7, 2023

Fontana is a great place to set up an accessory dwelling unit. However, before you decide to construct one for your backyard, make sure you know all the rules and regulations set by the State regarding its construction. In this article, we will list all the Fontana ADU requirements for you to build your dream home in the most efficient way possible. However, before learning the rules, you must get a good knowledge of the different types of ADUs you can build in Fontana.

Types of an ADU

Attached ADU

The first type of accessory dwelling unit is the attached ADU. As the name suggests, the ADU is attached to the primary dwelling but has a separate entrance. The walls of the ADU are joined with the walls of the main building to make it look like a single unit. However

Detached ADU

The second type of ADU is the detached ADU, which is placed at a distance from the primary dwellings. This type of ADU is isolated from the main dwelling and has separate utility connections, entrances, and, in some cases, separate parking as well.

Junior ADU

Junior ADU is a smaller version of detached ADUs. The size of a junior ADU can't get bigger than 500 square feet. The rules and regulations for such ADUs are also different from a conventional detached ADU.

Conversion ADU

As the name suggests, conversion ADU is built by the conversion of an existing structure, such as a garage, basement, or attic. These structures can also be expanded up to 150 square feet, but not more than that.

Types of an ADU

Fontana ADU Requirements and Regulation

Locations Allowed

You can only build ADUs in the areas that are zoned for residential use. Moreover, it is required that you have an existing single or multi-family home on the property. This would make you eligible for the building of an additional accessory dwelling unit beside your primary dwelling.

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Size Restrictions

You just can't make a prefab ADU of any size you want, as there are some restrictions to that as well. The maximum size that you can go for is 800 square feet, considering that you are building it on a single-family dwelling. You can also build larger sizes as well, but it requires permission from the local ordinances and some special requirements to be met.

Number of ADUs Allowed

The total number of ADUs allowed with a single-family home is one. However, you can have one conversion ADU and one detached ADU at the same time. On the other hand, multi-family dwellings can have two detached units and an attached conversion unit at a time.


The minimum setback from the rear and side of the primary building should be at least 4 feet. However, the setbacks for the street side must be greater than 4 feet. Keep in mind that these setback requirements are only for the detached and attached ADUs, as conversion ADUs are a part of your current structure.

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Parking Requirements

For a single-bedroom ADU, you can have one separate parking space. However, you are not required to have a separate parking if a public transit is located only half a mile away from your accessory dwelling unit. Moreover, you should also keep in mind that if you convert one of your current parking spaces into an ADU, you are not required to replace it with a new one.

Height Restrictions

As far as the height of your Fontana model homes is concerned, you are only allowed to build your ADU at around 16 feet in height. However, this restriction is only for the detached ADUs, as attached ones can go up to 25 feet to match the overall height of the primary dwelling. For conversion ADUs, any kind of height restrictions are not applicable.

Owner Occupancy

Owner occupancy is not required for the ADUs or mobile homes in Fontana CA permitted between 2020 and 2025. It means that you can have your ADU legally registered as a part of your property without having to occupy it for any specific period of time.

Fire Safety

Although installation of fire sprinklers is not required for your accessory dwelling unit, if they aren't required for your primary dwelling, we highly recommend installing them in order to keep your property safe.

Fire Safety

Permit Process

The permit process of your ADU would take around 60 days to complete. The process will take much less time if your design and construction plan match the guidelines and California ADU law 2023. On the other hand, you must pay a permit fee in order to get your application processed. However, the fees are not applicable to ADUs with less than 750 square feet of living area.

Rental Allowance

Rental service can be offered on your prefab homes in California, but make sure that you rent it out on a term longer than 30 days. This is a great opportunity for those looking to earn quick profits from their ADU investments.

Utility Connection

To balance the division of power to both the detached ADU and the primary dwelling, you need to attach a separate meter for your accessory dwelling unit. Although it is not one of the ADU California requirements, it is highly recommended for providing ample power for your ADU to operate correctly. Moreover, if you are choosing a container home in California, a separate utility connection would make your life much easier, as wiring in such homes is extremely difficult. On the other hand, the ones opting for a private sewage disposal system must get it reviewed by the local health officer before making the final construction.

Utility Connection - fontana adu requirements

Design Review

Before submitting your application for the permits, make sure you check the design of your tiny home kits. The design of your ADU must not violate any condition or rule set by the State, which includes the number of bedrooms, bathrooms, kitchens, and parking spaces.


Fontana is undoubtedly a great place to set up an ADU. However, All the Fontana ADU requirements listed in this article are required to be fulfilled in order to make your ADU permit process successful, so make sure you pay close attention to all the details mentioned above and enjoy an amazing living experience.

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