Santa Ana Zoning and ADU Guide for Homeowners and Sellers

Last updated November 13, 2026. Reviewed by the Cash Home Buyers CA team. Information comes from the City of Santa Ana; sources are listed at the end.

Santa Ana regulates ADUs under Zoning Code Section 41-194, which allows up to one ADU and one junior ADU on a single-family lot. Multifamily properties can add detached ADUs, subject to limits tied to the number of existing units, and the city offers pre-approved ADU plans.

Santa Ana ADU rules at a glance

Code section	Santa Ana Zoning Code Section 41-194
Single-family lots	Up to one ADU and one junior ADU
Multifamily lots	Up to eight detached ADUs, not exceeding the number of primary units, and up to 25 percent of existing units
Pre-approved plans	Available from the city
Who to call	Planning Division, (714) 647-5804

Why check size and setback rules with the city?

Size caps, setbacks, parking and owner-occupancy rules depend on the type of unit and the lot, and state law has changed these rules several times. This guide does not list those figures. Confirm them with the Planning Division before you market a house as having a legal second unit.

How ADUs and zoning affect selling a house in Santa Ana

A permitted ADU can be a selling point, but a converted garage or backyard unit with no permit is something buyers’ inspectors and lenders flag. In California, sellers generally have to disclose known unpermitted work. Your choices are to permit the unit, remove it, discount the price, or sell as-is to a cash buyer who accounts for the risk. See our Santa Ana building permits guide for the lookup tools.

How to sell a house in Santa Ana with an unpermitted ADU

1. Check the permit record. Search the address in Property Information to see whether the unit was ever permitted.
2. Check for complaints. Ask Code Enforcement at (714) 667-2780 whether any case is open.
3. Weigh the options. Permit it, convert it back, sell with a credit, or sell as-is.
4. Disclose honestly. A cash offer does not change what you must disclose, but it removes repairs and inspections from the timeline.

We buy Santa Ana houses as they are, including houses with converted garages and backyard units. Read how selling a house as-is in Santa Ana works, or see our Santa Ana cash-offer process. If the house has been cited, read our Santa Ana code enforcement guide.

Not sure whether your unit is legal? Call (424) 435-2326 or request a cash offer. There is no cost and no obligation.

Single-family lots versus multifamily lots

Santa Ana’s Section 41-194 treats the two lot types very differently, and that matters for how a buyer values the property. On a single-family lot the city allows up to one ADU and one junior ADU.

On a multifamily lot it allows detached ADUs, up to eight, but never more than the number of primary units, plus conversions of existing space up to 25 percent of the existing units. A fourplex owner, for example, is working with a different set of limits than a single-family owner.

If you own a duplex or larger building, ask the Planning Division which limits apply to your lot before you tell buyers what could be added.

What state law says about converting existing space

California requires cities to allow certain ADUs created inside space that already exists, such as a garage or other accessory structure, without requiring a new building. For multifamily buildings, state law also allows converting non-livable space such as storage rooms, basements or garages into units.

These rules set a minimum that Santa Ana’s code has to respect, so a house with a converted garage may be closer to legal than a seller assumes. The catch is that conversion still needs a permit, inspections and compliance with fire and life-safety standards.

Why pre-approved plans matter to a buyer

The city offers pre-approved ADU plans. For a buyer who wants to add a unit after closing, that can lower design cost and uncertainty. If your lot has room, mentioning the plan program is a reasonable way to explain the potential of the property, as long as you are clear that the city must still approve the unit on your specific lot.

A four-point check on whether a unit is legal

1. Permit: Is there a permit for the unit, and was it finaled?
2. Use: Does the unit have its own kitchen, bathroom and entrance, as the permit describes?
3. Utilities: Are electrical, water and sewer connections what the permit shows?
4. Records: Are there any recorded documents or city conditions tied to the unit?

If any of the four answers is no or unknown, treat the unit as unpermitted for disclosure purposes until the city confirms otherwise.

How the unit affects what a buyer will pay

A legal, finaled ADU can add rental income and buyers may pay for it. An unpermitted unit can have the opposite effect, because buyers have to budget for permitting or removal and lenders may not count the space.

Income-property buyers will also ask for rent rolls and lease terms if the unit is occupied. That is why the same square footage can lead to very different offers depending on its legal status.

More Santa Ana ADU questions

Can a duplex owner add ADUs in Santa Ana?

The city lists detached ADU allowances for multifamily properties, tied to the number of existing units, so it may be possible. The Planning Division can confirm what your lot allows.

Is a pre-approved plan a permit?

No. A pre-approved plan is a design the city has already reviewed. You still need a permit for your lot, with the required inspections.

Who should I call with an ADU question?

The Planning Division at (714) 647-5804. Ask for the current code section and any handouts for your lot type.

Santa Ana zoning and ADU FAQ

How many ADUs can I build in Santa Ana?

On a single-family lot, up to one ADU and one junior ADU. Multifamily properties can have up to eight detached ADUs, limited by the number of primary units.

Does Santa Ana have pre-approved ADU plans?

Yes. The city offers pre-approved ADU plans. Call the Planning Division at (714) 647-5804 with questions.

Can I sell a Santa Ana house with an unpermitted ADU?

Yes. The sale is not legally blocked, but you should disclose the unit. A cash buyer can purchase the house as-is with the unit unpermitted.

Which Santa Ana code section covers ADUs?

ADUs are regulated under Zoning Code Section 41-194.

Sources

• City of Santa Ana: Accessory Dwelling Units, Zoning Code Section 41-194
• California Government Code section 66314 (ADU ordinance standards)

This guide is general information, not legal advice. ADU rules change often; confirm requirements with the City of Santa Ana Planning Division.