ADU Knowledge
June 11, 2024

How much does a Garage Conversion ADU cost in Orange County?

Argi Avetisyan
Argi Avetisyan
Gather ADU expert
How much does a Garage Conversion ADU cost in Orange County?
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Are you thinking about converting your garage into a stylish, functional living space? You're not alone! Garage conversion ADUs (Accessory Dwelling Units) are becoming a popular choice for homeowners in Orange County. This trend is driven by the need for additional living space, potential rental income, and the desire to add value to existing properties. But how much does it really cost to convert a garage into an ADU in Orange County? Let's break it down.

What is a Garage Conversion ADU?

An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family residential lot. These units can be attached or detached from the main house and serve as a functional living space. Garage conversions are a popular type of ADU, where an existing garage is transformed into a livable area. This option is particularly appealing because it utilizes existing structures, making it a more cost-effective and quicker alternative to building a new unit from scratch.

Factors Influencing Cost

Several factors can influence the cost of converting a garage into an ADU. Here are some key considerations:

Size and Design Preferences

The size of your ADU will significantly impact the overall cost. Larger units tend to have a lower cost per square foot but require more materials and labor. Design preferences, such as the layout and interior finishes, will also affect the final price.

Material Selection and Quality

The choice of materials plays a critical role in determining the cost. High-end finishes and premium materials will naturally increase the budget, while more economical options can help keep costs down.

Permits and Legal Requirements

Permits and legal requirements vary by location. In Orange County, specific permits are needed for garage conversions, and these can add to the overall cost. It's essential to consult with local authorities to understand the necessary permits and associated fees.

Labor Costs and Timeline

Labor costs can vary based on the complexity of the project and the expertise of the contractors involved. Additionally, the timeline for completion can affect costs, with longer projects potentially leading to higher labor expenses.

Real Cost Breakdown

Converting a garage into an ADU in Orange County typically costs between $200 and $300 per square foot. For a standard two-car garage (approximately 400 square feet), this translates to $90,000 to $120,000. Here's a detailed breakdown:

  • Construction Costs: $200 - $300 per square foot
  • Architects & Engineering: $8,000 - $25,000
  • Designers, Landscapers: $2,500 - $8,000
  • Civil Engineers: $2,500 - $5,000
  • Plan-check and Permit Fees: $5,000 - $10,000
  • School Fees (over 500 SF): $1,000 - $3,000
  • Impact Fees (over 750 SF): $3,000 - $10,000
  • Solar (Most detached ADUs): $8,500 - $10,000

Return on Investment (ROI)

Investing in a garage conversion ADU can offer significant financial benefits. Not only does it provide additional living space, but it can also increase property value and generate rental income. Many homeowners find that the ROI justifies the initial investment, making it a financially sound decision.

Case Studies and Examples

Garage Conversion in Orange County

Let's explore some real-life examples of homeowners in Orange County who have successfully converted their garages into ADUs. These stories highlight the costs, challenges, and benefits experienced during the process:

1. One family converted their detached garage into a modern one-bedroom unit for $110,000. They now rent it out for $1,800 per month.

2. Another couple opted for a high-end conversion with premium finishes, costing $140,000. The unit serves as a guesthouse and home office.

3. A third household transformed their garage into a cozy studio apartment for $95,000. They use it as an in-law suite for visiting family members.

Steps to Get Started

Ready to start your garage conversion ADU project? Here are some initial steps to guide you:

  1. Budget Planning: Assess your finances and determine a realistic budget for the project.
  2. Find the Right Contractor: Research and hire a reputable contractor with experience in ADU conversions.
  3. Obtain Necessary Permits: Consult with local authorities to secure the required permits for your project.


Garage conversion ADUs offer a practical and cost-effective solution for homeowners in Orange County looking to maximize their living space and increase property value. By understanding the costs involved and following the outlined steps, you can make an informed decision and embark on a successful ADU project. Ready to take the next step? Contact our ADU experts  and discover how we can help you transform your garage into a functional and stylish living space. Share this post with others who might find it helpful, and let's build a community of informed and empowered homeowners.

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