Accessory Dwelling Units (ADUs) are becoming a key part of Santa Ana’s housing strategy, thanks to California’s ongoing efforts to support housing growth and affordability. Whether you're a homeowner, investor, or contractor, understanding the ADU laws in Santa Ana — and knowing how to get an ADU permit in Santa Ana — is essential before planning your next project.

In this 2025 guide, we break down everything you need to know — from zoning codes and setback requirements to permitting, utility rules, and rental restrictions — to help you build or rent an ADU in Santa Ana legally.

What Is an ADU?

An Accessory Dwelling Unit (ADU) is a self-contained residential unit located on the same lot as a primary home. It has its own kitchen, bathroom, and entrance and can be attached, detached, converted from a garage or basement, or even built as a Junior ADU (JADU) inside the main house.

Santa Ana ADU Laws & Regulations (2025)

1. Zoning Requirements

Santa Ana allows ADUs in all residential zones (R1, R2, R3, etc.) in compliance with California State Law.

You can build:

• One ADU and one JADU per lot (in single-family zones)

• Multiple ADUs in multifamily-zoned lots (converted or attached)

2. ADU Size Limits

• Detached ADUs: Up to 1,200 sq ft

• Attached ADUs: Cannot exceed 50% of the main home’s square footage

• Junior ADUs (JADUs): Max 500 sq ft

There is no minimum lot size to build an ADU in Santa Ana.

3. Setback Requirements

• Side and rear setbacks: Minimum 4 feet

• No setback required if converting an existing permitted structure (e.g., garage)

4. Height Limits

• Detached ADUs: Typically 16–18 feet, depending on location and lot

• ADUs within half a mile of transit may qualify for two stories (25 ft max) under state law

5. Parking Requirements

• No parking required if:

  • The ADU is within ½ mile of public transit

  • It’s part of a garage conversion

  • It’s located in a historic or environmentally sensitive district

🚫 Replacement parking is not required when converting a garage into an ADU.

6. Permit & Approval Process

• Submit building plans to the Santa Ana Planning and Building Agency

• Most permits are reviewed within 60 days as per state ADU laws

• Use pre-approved ADU plans for faster approval if available

7. Utility Connections

• ADUs may share utilities with the main house

• For detached ADUs, separate utility meters are optional

• Impact fees apply only if the ADU is larger than 750 sq ft

8. Rental Rules for ADUs in Santa Ana

• ADUs must be rented for 30 days or longer (short-term rentals like Airbnb are prohibited)

• No owner occupancy requirement for ADUs built between 2020 and 2025

• JADUs do require owner occupancy on the lot

Why Build an ADU in Santa Ana?

• Rental Income – ADUs rent for $1,500–$2,800/month in Santa Ana

• Multigenerational Living – Perfect for elderly parents or college students

• Home Office or Studio – Separate work-from-home space

• Increased Property Value – Up to 20–30% added value