How Much Does an ADU Cost To Build in Los Angeles?

By Babak Mortazavi October 3, 2025

In Los Angeles, the cost to design and build an ADU (accessory dwelling unit) can range from $150,000 to over $400,000, depending on the size, type, and complexity of the project.

With construction costs averaging $300 to $400 per square foot, many homeowners are asking the same question: How much does an ADU cost to build in Los Angeles?

Whether you're considering a garage conversion, a detached backyard unit, or a two-story addition, understanding the full scope of ADU costs can help you plan smarter and avoid unexpected expenses.

In this article, we'll break down:

What impacts the total ADU project cost in Los Angeles.
How the size of the ADU affects price.
Differences in cost by type of ADU.
What's included in construction costs vs. soft costs such as permits and design.
How LADU's fixed pricing and in-house team helps homeowners stay on budget.

By the end of this guide, you'll understand the true cost of an ADU in Los Angeles and how LADU makes ADU construction simpler, more transparent, and more predictable from day one.

Schedule your free consultation with LADU today to learn more about the benefits of adding an ADU to your property and how we simplify the process with end-to-end project management.

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

Average Cost To Build an ADU: Price Range for ADUs in 2025

The average cost to build an ADU in Los Angeles in 2025 ranges from $150,000 to $400,000+. The actual price can vary depending on factors like the ADU type, size, site conditions, and finish level. For example:

A basic garage conversion can start around $95,000 and climb to $225,000, depending on upgrades and structural improvements.
A detached ADU in the backyard typically costs between $200,000 and $350,000 for a one-story unit, with two-story designs pushing that number higher.
Attached ADUs, i.e., those connected to the main home, usually fall in the mid-range due to shared walls and utilities.

Prefab ADUs typically cost less to purchase, but once you factor in site preparation, transportation, and installation fees, the price of a prefab ADU is usually comparable to building from the ground up and offers a similar return on investment.

The California ADU Grant Program can help homeowners reduce costs by up to $40,000 and is well worth looking into.

What Impacts the Final Cost To Build an Accessory Dwelling Unit?

Several key factors influence the total cost of your ADU building project in Los Angeles:

ADU Size: Larger ADUs require more materials and labor, but they often have a lower cost per square foot.
Construction Complexity: Two-story ADUs, hillside builds, or custom designs can significantly increase costs.
Site Conditions: Properties with poor soil, steep slopes, or limited access may require grading, retaining walls, or additional engineering.
Material and Finish Choices: High-end cabinetry, flooring, and fixtures can quickly add tens of thousands to your total budget.

LADU's ADU Pricing Approach

At LADU, we've simplified the cost planning process with a transparent pricing model. Our flat-fee design packages help homeowners avoid scope creep and unexpected costs. You'll know exactly what your ADU will cost before we build it.

New California state laws have made building an accessory dwelling unit easier than ever before for Los Angeles homeowners. Now is the ideal time to consider investing in an ADU.

How Size and Type Affect the Cost of Building an ADU

ADU Cost by Square Foot

In Los Angeles, ADU construction costs typically range from $300 to $400 per square foot. For larger units, costs may drop closer to $250 per square foot due to economies of scale.

For example, a 1,200 sq. ft. ADU may cost less per square foot than a compact 500 sq. ft. unit with similar finishes.

Cost by ADU Type

Here's how the cost of constructing an ADU varies by type and typical square footage:

Garage Conversion: $95,000–$225,000. Converting an existing garage into a living space is often the most cost-effective route.
Attached ADU (500–1,000 sq. ft.): $175,000–$325,000. These units share infrastructure with the main house, which can bring savings.
Detached ADU (up to 1,200 sq. ft.): $200,000–$400,000+. These standalone structures offer more privacy and flexibility but come at a higher cost due to separate foundations, utilities, and framing.

Choosing the Right ADU Size for Your Budget

The best ADU size depends on your goals. A 500 sq. ft. ADU will cost less and may be ideal for a guest suite or home office, while an 800–1,200 sq. ft. ADU could serve as a full rental or multigenerational home.

LADU's team helps homeowners match their budget with the right ADU design and layout.

Understanding ADU Building Costs: Cost Breakdown

ADU Design and Architecture Fees

Professional ADU design is more than just floor plans. LADU's architect-led design team handles:

Site evaluations.
Schematic designs.
Code-compliant construction drawings.
Permit-ready plan sets.

Typical design fees range from $8,000 to $25,000+, depending on complexity and site-specific requirements.

ADU Permit and City Fees

ADU building permits in Los Angeles are required and generally cost between $5,000 and $10,000. These fees include:

Plan check and review.
School impact fees.
Utility connection fees.
City inspections.

Each city may have slightly different requirements, so LADU's in-house permitting experts manage the process for you.

ADU Construction and Site Work

Construction costs include:

Foundation and framing.
Roofing and insulation.
Plumbing and electrical systems.
Interior finishes and fixtures.

Site conditions associated with ADU construction, such as grading, tree removal, or retaining walls, can significantly affect the total cost of building an ADU. LADU evaluates these factors during your free site assessment.

Los Angeles ADU Cost per Square Foot

500 Sq. Ft. ADU Cost

Expect to spend between $150,000 and $200,000 for a 500 sq. ft. ADU. These units are ideal for compact rental suites or a guest house and can be built as garage conversions or small detached units.

800 Sq. Ft. ADU Cost

An 800 sq. ft. ADU typically costs $200,000 to $275,000, depending on the complexity. This size allows for a comfortable one-bedroom or two-bedroom layout with mid-range finishes and efficient use of space.

1,200 Sq. Ft. ADU Cost

A full-size detached ADU at 1,200 sq. ft. can range from $300,000 to $400,000+, especially if it includes two stories or high-end materials. This size offers the most flexibility for long-term rental or multigenerational use.

How ADU Regulations and Site Conditions Impact ADU Costs

Hillside Lots, Setbacks, and Soil Conditions

Building an ADU on a sloped or irregular lot can increase the overall cost due to:

Grading and excavation.
Retaining walls.
Structural engineering.
Additional inspections.

Setback requirements may also limit your buildable area, requiring creative design solutions.

Utility Access and Upgrades

Connecting your new ADU to existing water, sewer, gas, and electrical lines can add several thousand dollars to your total cost, especially on older properties. In some cases, utility upgrades may be required to meet code.

Additional Property Improvements

Don't overlook the extras. Landscaping, fencing, driveways, and hardscaping are often outside the base construction budget but can add significant value, as well as cost, to your ADU project.

Garage Conversions: A Cost-Effective ADU Option

Why Garage Conversions Cost Less

Garage conversions often cost less than new construction because they reuse existing foundations, framing, and roofing. This reduces material and labor costs while speeding up the construction timeline.

Common Garage Conversion Costs

Basic conversions: $95,000–$150,000
Mid-range conversions: $150,000–$175,000
High-end conversions with structural upgrades: Up to $225,000

What To Know Before You Convert

Before starting a garage conversion, consider:

Structural condition of the garage.
Ceiling height (minimum 7'6" is typically required).
Local zoning and ADU permit requirements.

ADU Building Permit and Timeline Considerations

How Long Does Permitting Take?

In Los Angeles, ADU permits typically take 2–3 months to process. Timelines vary based on project complexity, city workload, and responsiveness to plan check comments.

Common Permit Requirements

To get an ADU permit, you'll need:

A site plan and floor plan.
Structural and engineering drawings.
Title 24 energy compliance documents.
Fire safety and access documentation.
To pay all permit fees.

Obtaining ADU building permits is non-negotiable. Building an unpermitted ADU risks fines, stop-work orders, and even forced demolition.

LADU's Permitting Expertise

Permitting can be one of the most stressful parts of building an ADU. LADU's in-house team works directly with city planners and inspectors to streamline the process and keep your project on schedule.

How LADU Simplifies the ADU Cost Planning Process

One Team. One Contract. One Goal.

LADU is a full-service ADU firm offering design, permitting, and construction coordination under one roof. This integrated approach ensures better communication, faster timelines, and fewer surprises for homeowners.

Transparent ADU Pricing Without Surprises

Our flat-fee design packages and fixed construction pricing mean you'll never be caught off guard by unexpected change orders or hidden fees. We believe in clarity from day one.

Free Site Assessments and Consultations

Every LADU project starts with a free site visit. We'll assess your property, discuss your goals, and provide a clear, personalized quote.

Budgeting Tips for Homeowners Planning an ADU

Start With a Realistic Budget Range

For most Los Angeles homeowners, a smart starting point is $250 to $400 per square foot. This range accounts for quality construction and the local cost of labor and materials.

Don't Forget the Soft Costs

In addition to construction, your total ADU budget should include:

Design and engineering fees.
Permitting and city fees.
Utility hookups and inspections.
HVAC installation and appliances.
Desired extra features such as solar panels.

These "soft costs" can add $20,000 to $40,000 or more to your total.

Plan for Contingencies

Older homes, sloped lots, or unknown site conditions can lead to surprises. We recommend setting aside 10–15% of your budget as a contingency reserve.

ADUs as Long-Term Investments

The benefits of investing in an ADU are undeniable. There are several reasons so many LA owners are considering adding an accessory dwelling unit to their property:

Rental Income Potential

A well-designed ADU can generate $1,500 to $3,500+ per month in rental income, depending on location and unit size. This income can help offset your construction cost over time.

ADUs and Property Value

Adding an ADU can increase your property's resale value and expand its appeal to future buyers, especially in high-demand areas of Los Angeles.

Multi-Use Flexibility

ADUs aren't just for rental income. They're perfect for multigenerational living, guest accommodations, or home offices.

Want To Build an ADU? Let's Talk.

The cost to build an ADU in Los Angeles varies widely from $150,000 to over $400,000, depending on size, type, site conditions, and design choices. Planning for architecture, permits, construction, and site work is essential for accurate budgeting.

At LADU, we make the process simple. Our architect-led, all-in-one model combines design, permitting, and construction coordination under one expert team, with full transparency and no surprises.

Book your free site assessment with LADU today, and take the first step toward building your ADU with confidence.

Need To Get a Clear ADU Cost Estimate for Your Property?

By now, it's clear that the cost to build an ADU in Los Angeles can vary significantly, ranging from around $150,000 for a simple garage conversion to over $400,000 for a custom, two-story detached unit.

Key factors such as ADU size, construction type, site conditions, and finish level all play a role in shaping your total investment.

With LADU's architect-led, all-in-one approach, homeowners don't have to guess their way through the process.

From ADU design and permitting to construction, LADU offers competitive pricing and a single point of accountability so there are no surprises along the way.

Our experienced team knows how to navigate Los Angeles zoning laws, utility requirements, and permit timelines to keep your project on track and within budget.

Call (213) 855-3334 today to speak with an ADU expert and start designing your new ADU.