ADU Regulations in Santa Ana: A Comprehensive Guide
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ADU Regulations in Santa Ana: A Comprehensive Guide

|Oct 28, 2023

If you are deciding to build an ADU in Santa Ana, make sure to understand all the rules and regulations in detail. There are plenty of restrictions and regulations that are required to be met in order to become eligible for the construction of a JADU or an ADU.

In this article, we will discuss all the rules regarding permitted zones, the number of ADUs allowed per zone, the maximum size of an ADU in Santa Ana, etc.

Types of ADUs

Rules for ADUs are different for different types. To better understand the rules, let's learn the different types of ADUs that you can build.

Attached ADUs

An attached ADU in Santa Ana, as the name suggests, is built as an expansion of your current home. They are not free-standing buildings but prefab accessory dwelling units built to increase the overall area of your house.

Detached ADUs

Detached ADUs are free-standing buildings that are constructed at some distance from your house within the premises of your home. These ADUs can be built with single or multiple-family buildings in order to expand living or working areas without attaching them to the main dwelling.

Types of ADUs


Junior ADUs are built by converting the existing area of your single-family or multi-family residence into an accessory dwelling. In JADU, you can share the bathroom with your primary dwelling; however, everything else would remain unshared.

Conversion ADUs

Conversion ADUs are similar to JADUs, but you won’t be converting a part of your primary dwelling. Here, you will pick an existing structure separate from your primary dwelling for conversion. An example of such structures could be a garage or a shed.

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Permitted Zones

The ones looking to build an accessory dwelling unit in their house should know that the ADUs, attached or detached, can only be built in the zoning districts where mixed-use development or residential development is allowed.


The design must be according to the building regulations, which would make the approval of the building permission application much smoother. Application submitted would require some time to get the approval. If your design doesn't match the rules and regulations, it would mention the areas where it needs rectification. The fee for the application is non-refundable, so make sure you check the design properly. For proper design, make sure to follow the rules and regulations listed below.

Design - ADU Santa Ana

City of Santa Ana ADU Requirements

Number Allowed

Lots developed for single-family residences would be allowed to have one accessory dwelling unit. Multiple detached single-family residences would have to face similar restrictions as well. However, multi-family residences can be built with a maximum of 2 detached accessory dwelling units. Moreover, keep in mind that the size of the ADU should not exceed 25 percent of the number of units built on a single lot. Detached ADUs can be built by converting the current accessory buildings such as garages, covered parking, carports, or other constructions. On the other hand, junior accessory dwelling units have similar regulations when it comes to single-family residences. Meanwhile, multiple detached single-family dwellings cannot have a JADU.

Lot Sizes

There are different size restrictions for different types of ADUs. Attached and detached Santa Ana ADU’s restrictions differ from JADUs when it comes to minimum size, which is 220 square feet. However, the maximum size for an ADU and JADU is 1000 square feet and 500 square feet, respectively. Keep in mind that your attached ADU should not be more than 50 percent of the size of your primary dwelling, or if it exceeds, it shouldn't be more than 800 square feet.

For the conversion ADUs in Santa Ana, you can only expand up to 150 square feet of your existing structure area. The expanded area would not be subject to the development standards that you need to meet for new ADUs, and it would only be considered as a part of your existing ADU. For expansions above 150 square feet, you will need permission and have to follow all the development standards required to be fulfilled for additional ADUs in Santa Ana.

On the other hand, the maximum height for the attached ADU and JADU should be the same or lower than the primary building. However, detached ADUs should be as high as 20 feet with a maximum of 2 stories. The height requirements are not applicable for converted ADUs.

City of Santa Ana ADU Requirements


The minimum front yard setback should be the same as the primary building for all kinds of ADUs. However, the minimum side yard setback should be at least 4 feet from the primary dwelling for attached and detached ADUs. JADUs can have setbacks similar to the primary buildings.

Parking Requirements

Parking requirements for your ADU depend on some conditions. If any of the following applies, then you don't need to build separate parking for your ADU

  • Your ADU is located only half a mile away from public transit, such as a train station or bus stand.
  • Your ADU is on the premises of your primary dwelling and is attached to it.
  • Your ADU is constructed for an office or some purpose other than living. This kind of ADU doesn't have bedrooms.

On the other hand, if you convert your existing garage or parking space to an ADU, the construction of a separate parking space would not be required. The demolition permit would be issued with the permission for building the ADU in Santa Ana.

Selling of an ADU

If you are building an ADU to sell it for some extra profits, keep in mind that the rules in Santa Ana don't allow you to do that. An ADU, regardless of the type, cannot be sold separately from the main dwelling. It can only be sold with the primary dwelling, where you will have the power to control the price.

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