How to Build an ADU in Los Angeles in 2025

By Jacob Aghelian

On 25 February 2025

What is an ADU in Los Angeles?

An Accessory Dwelling Unit (ADU) is a secondary housing unit on a residential property. Homeowners in Los Angeles build ADUs to generate rental income, provide housing for family members, or increase property value. The process involves zoning regulations, permits, and construction planning.

How Does ADU Permitting Work in Los Angeles?

Los Angeles County has different permitting processes depending on the property’s location:

City of Los Angeles: Permits are issued by the Los Angeles Department of Building and Safety (LADBS).
Unincorporated LA County: Applications are submitted through EPIC-LA and reviewed by the LA County Department of Regional Planning.

What Are the Types of ADUs in Los Angeles?

Choosing the right ADU type depends on budget, available space, and property constraints:

Detached ADU: A separate structure from the main home.
Attached ADU: Connected to the existing home.
Garage Conversion ADU: Converts an existing garage into an ADU.
Junior ADU (JADU): A small unit (under 500 sq. ft.) within the main home.

How to Choose the Best ADU Type?

Large backyard? A detached ADU works well.
Lower budget? A garage conversion is cost-effective.
Faster approval? A pre-approved detached ADU plan speeds up the process.

What Are the Zoning Requirements for ADUs in Los Angeles?

Before designing an ADU, verify property eligibility based on zoning laws:

Allowed on single-family and multi-family zoned properties.
Setbacks: Minimum 4 feet from rear and side property lines.
Height Limits: Typically 16 feet, but varies by zoning.
Parking: Not required if within ½ mile of public transit.
Lot Coverage: ADUs must comply with property coverage limits.

How to Check Zoning Eligibility?

City of LA: Use ZIMAS to check zoning.
Unincorporated LA County: Use Z-NET for verification.

How to Get an ADU Permit in Los Angeles?

City of Los Angeles:

Submit an application to LADBS.
Obtain zoning clearance, plan approval, and building permits.

Unincorporated LA County:

Submit a Regional Planning – Base Application via EPIC-LA.
Review process takes up to 60 days after fee payment.

Tip: Using a pre-approved ADU plan can reduce approval time significantly.

Should You Use a Pre-Approved or Custom ADU Plan?

Pre-Approved Plans:

Approval Time: 2-3 weeks (faster than custom plans).
Cost: $5,000 – $10,000.
Limited customization.

Custom Plans:

Approval Time: 3-6 months.
Cost: $15,000 – $30,000.
Full design flexibility.

Which Option is Best?

Want faster approval and lower cost? Choose pre-approved plans.
Need a unique layout? Custom plans are better.

How Much Does It Cost to Build an ADU in Los Angeles?

Costs vary by size, materials, and plan type:

Expense	Low Estimate	High Estimate
Permits & Design	$5,000	$15,000
Site Prep & Foundation	$15,000	$30,000
Construction (Framing, Plumbing, Electrical)	$80,000	$150,000
Interior Finishes	$30,000	$60,000
Utility Connections	$5,000	$15,000
Total Cost	$135,000	$300,000+

What Are the Financing Options for ADUs in Los Angeles?

Homeowners can access several funding options:

CalHFA ADU Grant: Up to $40,000 for pre-development costs.
NHS LA County Loan: Offers up to $98,500 for low-income homeowners.
United Dwelling Program: Helps with development, financing, and property management.

What Is the ADU Construction Timeline in Los Angeles?

Building an ADU takes 6-12 months from start to finish:

Phase	Duration	Key Steps
Planning & Permits	2-6 months	Design, zoning approval, LADBS permits
Site Preparation	1-2 months	Land grading, utility connections
Construction	3-6 months	Framing, plumbing, electrical, roofing
Final Inspections	1-2 months	Safety checks, occupancy certificate