How Much Does It Cost to Convert a Garage to an ADU? [2026 Data]

In 2026, the national average cost to convert a garage to an ADU is $110,000. Most homeowners spend between $60,000 and $150,000, with garage size, location, and material choices as the primary cost drivers. You could pay as little as $25,000 for a single-car attached garage with budget-friendly materials, or as much as $225,000 for a larger detached garage converted into a rentable space with a full kitchen and bathroom.

Garage Conversion Cost by Garage Size

Garage size is one of the biggest cost drivers when converting a garage to an ADU, with most homeowners spending $150 to $400 per square foot. Calculating the cost difference between large and small garages isn't linear because infrastructure like sewer, plumbing, HVAC, and electricity carries a fixed cost regardless of square footage. 

In some jurisdictions, a one-car garage may not have enough floor space to qualify for ADU conversion without adding a second story, which can increase your total further.

Here's a look at average prices by common garage sizes:

Home Addition Contractor Costs: What to Expect

Labor accounts for 40% to 60% of your total garage-to-ADU conversion cost, averaging $45,000 to $65,000, with a significant share going toward a local home addition contractor. This professional handles the main construction work but may subcontract specialized tasks like plumbing, electrical, and HVAC to tradespeople. 

Getting itemized quotes from your contractor up front helps you understand exactly where labor dollars are being allocated. Here’s what you can expect to pay for each project in your new ADU:

• Kitchen installation costs: $100 to $300 per sq. ft.

• Bathroom installation costs: $200 to $250 per sq. ft.

• Flooring installation cost: $1,500 to $4,800

• Cost to install drywall: $1,000 to $3,200

Architect and Structural Engineer Costs: What to Expect

Most garage-to-ADU conversions require both an architect and a structural engineer, with architect plans running $2,000 to $6,600 and structural engineering services billed at $70 to $250 per hour. An architect designs the custom layout, while a structural engineer reviews and approves any load-bearing or structural modifications. 

Even if your conversion involves minimal structural changes, your municipality will likely require a building permit before work can begin. Confirm professional licensing and ask for references before signing contracts with either specialist.

Interior Designer Costs: What to Expect

A professional interior designer can be especially valuable for a garage ADU conversion, where maximizing limited square footage is critical to creating a functional, rentable space. Interior designer prices range from $50 to $200 per hour, depending on experience and project scope. If you plan to rent the ADU, a well-designed layout can directly improve tenant appeal and long-term return on investment.

Here's what you’ll pay to have a designer review and plan-out your space:

• Cost to design a layout: $1,000 to $2,500

• Kitchen design: $600 to $1,500

• Bathroom design: $600 to $1,400

• Interior design and decor: $1,000 to $5,000

Additional Pros to Consider Hiring: What to Expect

A garage-to-ADU conversion is a complex project that often requires multiple specialized tradespeople, particularly if you aren't working with a general contractor who manages subcontractors on your behalf. The specific pros you'll need depend on your garage's existing condition and the scope of work involved. Below are other pros you may need to hire, along with average costs:

• Cost to hire a carpenter: $75 to $125 per hour

• Cost to hire an HVAC specialist: $100 to $250 per hour

• Cost to hire a plumber: $45 to $200 per hour

• Cost to hire an electrician: $50 to $130 per hour

• Cost to install insulation: $40 to $80 per hour

• Drywall installer cost: $1,000 to $3,200

• Interior painter cost: $2 to $6 per sq. ft.

• Flooring installer cost: $2 to $25 per sq. ft.

• Window installer cost: $300 to $2,500 per window

Garage Conversion Costs by State: What Homeowners Pay

Where you live has a significant impact on your garage-to-ADU conversion cost, primarily because labor—which makes up 40% to 60% of the total—fluctuates with the local cost of living. Costs run highest near major metropolitan areas and in states with an elevated cost of living overall. Permit fees also vary by municipality, though they have a smaller effect on your final total than labor rates do.

Here’s what you’ll pay based on your state:

Garage Conversion Cost Factors: What Affects the Price?

Several variables beyond garage size and labor rates can meaningfully shift what you pay to convert a garage to an ADU. Understanding these factors before you budget helps you avoid surprises once the project is underway.

Demolition and Prep

Demolition and prep costs for a garage ADU conversion depend entirely on your garage's current condition, and can range from a few hundred dollars to several thousand dollars. Common prep tasks include garage door removal, structural damage repairs, roof inspection and repair, concrete floor patching, and resolving rainwater drainage issues. 

Getting a thorough inspection before finalizing your budget helps you anticipate prep costs rather than encounter them mid-project.

Materials

Material quality is one of the most controllable cost levers in a garage-to-ADU conversion, with per-square-foot costs ranging from $150 per square foot for budget finishes up to $400 for luxury options. Budget-friendly choices like asphalt shingle roofing, prefabricated cabinets, laminate countertops, and laminate flooring can bring a single-car garage conversion in at around $36,000 total. 

Upgrading to high-end finishes like marble countertops and hardwood floors pushes that same single-car garage to $96,000.

Type of Garage

Whether your garage is attached or detached is a major cost factor, because the type of ADU you can build depends directly on your garage's configuration and proximity to existing utility connections. An attached garage allows you to tie directly into your home's existing plumbing, electrical, and HVAC systems. A detached garage requires running new utility lines underground, which drives up conversion costs by 20% to 30%.

Permits

Permits are a required part of any garage-to-ADU conversion, with building permit costs running $1,200 to $2,000 depending on project scope and your municipality. Your contractor will pull the necessary permits, but the fees are your responsibility to cover. If you plan to rent the converted space, check with your local municipality about whether a separate rental permit is also required.

Post-Construction Cleanup

The cost of construction cleanup ranges from $140 to $710, depending on the size of the space and the extent of dust and debris left behind. Once your ADU conversion is complete, hiring a professional cleaning service is the fastest way to make the space move-in ready. 

Taxes and Insurance

Completing a garage-to-ADU conversion will likely increase both your property taxes and home insurance premiums, though the exact amounts vary based on your location, current property values, and local insurance regulations. 

Market conditions can also influence how assessors value the new living space. Speaking with an insurance agent and a tax professional before starting the project gives you a clearer picture of your long-term carrying costs.

Financing Costs

If you choose to finance your home addition, factor in the full cost of borrowing—including interest rates, monthly payments, and any reduced returns if you're drawing from an investment account. These costs won't appear on your contractor's invoice, but they can meaningfully affect your long-term total. 

Comparing loan products and rates before committing to financing helps you choose the most cost-effective path forward.

Converting a Garage Into an ADU vs. New Construction

Some homeowners may be tempted to build a new standalone ADU structure on their property instead of converting a garage into an ADU. However, it's almost always more cost-effective to convert the garage rather than start from scratch with new construction that adds to the footprint of your home. Converting a garage to an ADU costs an average of $110,000 , while building a new ADU from scratch costs an average of $180,000.

With that being said, building a separate ADU and leaving your existing garage as-is leaves you space to park your car and still adds square footage to your home, so if you have the property and the budget for it, building a tiny house instead of creating an ADU in your existing garage may be a better option.

You'll also have more opportunities to customize the space, including the layout, position, and orientation. If you have an attached garage, building a detached ADU instead of converting it will also give you and your guests more privacy.

Deciding between converting your garage and building new construction is another area where hiring a contractor is helpful. The contractor can help you choose the most cost-effective, fastest, and overall best method of adding an ADU to your property.

Tips to Reduce Cost While Converting a Garage to an ADU

Converting your garage to an ADU is a big project that can cost as much as $225,000 . The best tip for converting your garage is to set and maintain a realistic budget. Here are a few other ideas.

• Perform your own preparation work. Steps you may be able to do include patching the concrete floor and removing all of your possessions from the space.

• Consider using upcycled or recycled materials for parts of the project. Ask your contractor for any restrictions, as some materials may not be suitable.

• Choose budget-friendly materials. Simply going with more affordable materials like linoleum or vinyl flooring over hardwood and prefabricated kitchen cabinets over custom ones can cut your costs in half.

• Prioritize energy efficiency: Just like with main home renovations, upgrading insulation, windows, doors, appliances, and heating and cooling equipment to energy-efficient options will save you money over time on utility bills.

Does Converting a Garage to an ADU Increase Home Value?

In most cases, converting your garage to an ADU will increase the property value . Adding living space to a property can see investment returns of up to 70%. Additionally, if the new space will be a rental unit, it can even generate income and give you an ROI of well over 100%. However, there are some factors to consider before jumping in.

In some locations, garage space is precious. Having a space that protects vehicles from harsh weather is a huge selling point for many home buyers. If you replace the garage with an ADU, effectively removing garage parking from the property, there's a potential to turn off some would-be buyers when it's time to sell. This could negatively affect how much value your ADU adds .

Another factor to consider may be whether or not you want to be a landlord to the renters who move in. While the property value and your monthly income may increase, decide if having the additional responsibility is worth it to you in the long run.

Why You Should Hire a Pro to Convert Your Garage to an ADU

Acting as your own general contractor when converting your garage to an ADU can save between 10% and 20% of the job's cost. However, managing the large number of tradespeople and inspectors is challenging and time-consuming.

While DIYing some of the work can save money, it's worth hiring a local home remodeling contractor early in the process of converting your garage into an ADU for the best possible results. A professional who builds home additions can provide guidance and ideas and manage the entire project, from planning to final inspection and cleanup.

Here's why it's ideal to hire a garage conversion pro

Converting your garage to an ADU isn't a simple DIY project. Here's why you should always hire experienced pros for the job:

• Professionals know how to prevent structural issues, moisture problems, and foundation damage.

• Hiring pros ensures your project complies with building codes, zoning laws, and safety regulations.

• DIY conversions can lead to improper wiring, poor insulation, and structural concerns.

• Reputable pros carry insurance and offer warranties for added peace of mind.

• Professionally converted garages can increase your property value and enhance your home's functionality.

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We extensively research project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We rely on reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects. 

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