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How Much Does It Cost to Convert a Garage to an ADU? [2025 Data]
Normal Range: $60,000 - $150,000
The cost to convert a garage to an ADU ranges from $60,000 to $150,000, with an average of $110,000. Your total will depend on materials, size, condition, and labor fees.
How we get this data
Photo: John Keeble / Moment / Getty Images
Photo: John Keeble / Moment / Getty Images
Highlights
Garage size and the quality of materials are the most crucial factors to consider.
Converting a detached garage will be 20% to 30% more costly than converting an attached one.
An ADU can boost home value by adding square footage and earn you rental income in the meantime.
Adding square footage can raise your property taxes, so be prepared for higher long-term costs.
The average cost to convert a garage to an ADU—or an accessory dwelling unit—is $110,000. You could pay as little as $25,000 to convert a single-car attached garage with budget-friendly materials, and prices can go as high as $225,000 to convert a larger detached garage to a rentable space with a kitchen and bathroom.
Cost by Garage Size
Garage size is a major factor when converting a garage to an ADU. You’ll spend between $150 and $400 per square foot to convert your garage to a livable ADU, which means larger garages will cost more to convert.
Calculating the cost difference between large and small garages isn't linear due to the need for infrastructure like sewer, plumbing, HVAC, and electricity. The cost of running utilities to a garage will remain static regardless of the size. In some jurisdictions, a one-car garage doesn't have enough floor space to qualify for ADU conversion unless you add a second story, which can drive up your costs, too.
Here’s a look at the average price of garage ADUs based on common garage sizes.
| Garage Size One-car | Average Square Footage | Average Price Range |
|---|---|---|
| One-car | 240 | $36,000–$96,000 |
| Two-car | 360 | $45,000–$120,000 |
| Three-car | 704 | $75,000–$225,000 |
Home Addition Contractor Cost
Labor will account for between 40% and 60% of your total cost, or between $45,000 and $65,000, on average. A good portion of that total will go toward hiring a local home addition contractor. This professional will tackle much of the main construction work, although they may subcontract things like plumbing, electrical, and HVAC work to specialists.
Kitchen installation costs: $100–$300 per sq. ft.
Bathroom installation costs: $200–$250 per sq. ft.
Flooring installation cost: $1,500–$4,800
Cost to install drywall: $1,000–$3,200
Architect and Structural Engineer Costs
Photo: ferrantraite / E+ / Getty Images
Converting your garage to living space may require structural changes, in which case an architect and a structural engineer will be necessary. Even if you don’t make major changes to the layout, your municipality will likely require you to get a building permit for ADU construction or any garage conversion.
You’ll need an architect to design a custom space for you, and a structural engineer to sign off on any structural work. The cost to hire an architect depends on their experience and the project size. For a garage conversion, expect a price between $2,000 and $6,600 for a set of plans. The cost to hire a structural engineer ranges between $70 and $250 per hour.
Cost to draw up blueprints: $800–$2,700
Structural engineer plan costs: $300–$2,500
Cost to propose structural changes: $350–$500
Interior Designer Costs
Because of its small size, converting a garage to an ADU requires an excellent design plan to create a functional and comfortable home space, especially if you plan on renting the ADU as a standalone unit. A professional interior designer can help organize the minimal square footage to get the most value and utility possible. Interior designer prices range from $50 to $200 per hour.
Cost to design a layout: $1,000–$2,500
Kitchen design: $600–$1,500
Bathroom design: $600–$1,400
Interior design and decor: $1,000–$5,000
Additional Pros to Consider Hiring
Converting a garage to an ADU is a complicated and involved project that may require hiring other professionals, especially if you don’t hire a home addition company to act as your general contractor. Below are some other pros you may need to hire, along with average costs.
Cost to hire a carpenter: $75–$125 per hour
Cost to hire an HVAC specialist: $100–$250 per hour
Cost to hire a plumber: $45–$200 per hour
Cost to hire an electrician: $50–$130 per hour
Cost to install insulation: $40–$80 per hour
Drywall installer cost: $1,000–$3,200
Interior painter cost: $2–$6 per sq. ft.
Flooring installer cost: $2–$25 per sq. ft.
Window installer cost: $300–$2,500 per window
Cost by Location
The cost to convert a garage to an ADU varies by location in large part because labor costs, which account for 40% to 60% of your total, fluctuate based on the local cost of living. Conversion costs will be higher in areas near major metropolitan areas and in states with a higher cost of living. Permit costs will also vary based on your local municipality’s fee schedule, although this plays a much less critical role in your pricing.
| State | Average Cost |
|---|---|
| California | $160,000 |
| Florida | $113,000 |
| Georgia | $101,000 |
| Illinois | $105,000 |
| Michigan | $102,000 |
| New York | $136,000 |
| North Carolina | $108,000 |
| Ohio | $105,000 |
| Pennsylvania | $105,000 |
| Texas | $102,000 |
Additional Cost Factors
There are many additional cost factors to consider when converting your garage to an ADU.
Demolition and Prep
The physical preparation necessary before ADU construction can start will depend on your garage’s condition. Things to consider include garage door removal, repairing any damage to the structure, ensuring the roof is in good condition, concrete floor patching, and dealing with any rainwater drainage issues. These can add anywhere from a few hundred dollars to several thousand dollars to your total.
Materials
Your total cost and the price per square foot to convert a garage to an ADU will depend heavily on the quality of materials you choose. Budget-friendly options like asphalt shingle roofing, prefabricated kitchen cabinets, laminate countertops, and laminate flooring can keep your costs close to $150 per square foot, or $36,000 total for a single-car garage.
Splurging on high-end, luxury materials like marble countertops and hardwood floors can push per-square-foot costs to $400, putting the total for a single-car garage at $96,000.
Type of Garage
The type of ADU you’re building depends on the type of garage you have, and this plays a crucial role in the cost of running utilities to the area. With an attached garage, you can connect directly to your main home's plumbing, electrical, and HVAC systems. With a detached garage, you’ll need to run new utility lines underground to the ADU, driving up conversion costs by 20% to 30%.
Permits
Converting a garage to an ADU will require either general building permits or individual permits for roofing, plumbing, electrical, and HVAC work. Your professionals will pull the permits for you, but you’ll need to pay the fees. A building permit costs between $1,200 and $2,000 for a garage conversion, depending on project scope and your municipality. If you’re planning on renting the space, you may also need to get a rental permit.
Post-Construction Cleanup
Once construction of the ADU is complete, you can make it move-in ready by hiring a cleaning service to ensure all of the dust and debris are taken care of. The cost of construction cleanup ranges from $140 to $710.
Taxes and Insurance
Your property taxes and home insurance will likely increase after your ADU is complete. However, the amount varies based on everything from where you live to current property values, insurance prices and regulations in your area, and even market conditions. Speaking with an insurance and tax professional can be helpful before starting the project.
Financing Costs
Should you choose to finance your home addition, remember to include the cost of borrowing money for the job in terms of interest rates, monthly payments, and reduced returns if you're borrowing from an investment account. These won’t be up-front costs, but you should consider how they’ll affect long-term totals.
DIY Garage Conversion to an ADU vs. Hiring a Pro
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 all of the comings and goings of the large number of tradespeople and inspectors required is challenging and time-consuming.
It is also possible to perform some of the work yourself to save on labor. If you have some DIY experience, you can do things like install drywall, tape and spackle, paint, install flooring, and connect plumbing and lighting fixtures. However, most jurisdictions won't allow an unlicensed homeowner to install plumbing, electrical, or HVAC systems, nor will you be able to carry out any structural work yourself.
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 to an ADU for the best results possible. A professional who builds home additions can provide guidance and ideas and manage the entire project, from planning to final inspection and cleanup.
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.
Pro Tip
There is some demand in the market for ADU's, specifically in-law suites. Most of this is driven by new homebuyers looking for ways to help pay their mortgage by renting space without having to qualify for an additional loan to purchase a separate investment property. This has increased as mortgage rates have continued to increase and homebuyers look for ways to save.
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