The cost to add a room above a garage ranges from $25,000 to $80,000, with an average of $50,000. Your total cost will depend on the type of room you add, the size, and materials.
The size of the room and how you use the space affect costs the most.
Building a room over the garage provides an average ROI of around 70%.
Adding a kitchen or bathroom to the space will increase costs significantly.
Don’t forget to budget for permits; costs vary based on your building department.
The average cost to add a room above a garage is $50,000. You’ll pay just $10,000 to add general living space over a single-car garage or as much as $270,000 to build over a three-car garage with a kitchen and bathroom to create a separate living area. The cost per square foot for the conversion is between $100 and $300.
The type of room above your garage you add will have a significant impact on your overall price. Open living space or an added bedroom that just requires a connection to your heating, cooling, and electrical systems and doesn’t require any special installations will be the most affordable. You can also opt to install an in-law suite or attached ADU, but adding a kitchen and a bathroom can triple your per-square-foot costs.
Type of Room Above Garage | Average Cost |
---|---|
Living space | $50,000–$100,000 |
In-law suite/ADU | $80,000–$210,000 |
Storage space | $10,000–$50,000 |
Building an over-the-garage addition can cost between $100 and $300 per square foot, so the size of your garage room addition plays another important part in the price tag for this project. The average garage size ranges from 240 to 704 square feet, depending on how many cars it holds. You can get an idea of the cost to add a room above your garage based on your garage size using the table below.
Garage Type | Room Size (Sq. Ft) | Average Cost Range |
---|---|---|
1-car | 240 | $24,000–$72,000 |
2-car | 360 | $36,000–$108,000 |
3-car | 704 | $70,000–$210,000 |
Between 40% and 60% of your total will go toward labor, and nearly all of that will go to a local home addition contractor. This pro may use in-house specialized contractors like plumbers, electricians, and HVAC techs to handle utilities, and they’ll tackle the construction and finishing themselves. Below are some of the common tasks a home addition contractor will handle, along with average costs.
Framing the add-on: $4–$16 per sq. ft.
Installing the roof: $4–$11 per sq. ft.
Installing siding: $1–$13.50 per sq. ft.
If you envision your new room above your garage as a living space, you’ll need a way to heat and cool your addition. Your home addition contractor will often have an HVAC tech on staff, but if you instead choose to hire individual professionals for each portion of the job, you’ll need to coordinate with a local HVAC pro. Depending on what systems you choose, you can expect to pay anywhere from $2,000 to $14,500 for HVAC.
Ductwork installation: $300–$2,100
Installing a ductless mini-split: $2,000–$14,500
Installing a standalone central AC unit: $3,000–$8,000
Similarly, you’ll need to hire an electrician to extend your existing electrical system up into the room above your garage. Hiring an electrician costs an average of $50 to $130 per hour, but you could see a flat fee of between $500 and $1,500 for this project. Some projects for your above-garage room include the following.
Installing an outlet: $100–$450
Adding a light fixture: $150–$1,000
Installing a light switch: $100–$200
Depending on the type of room you’re planning to build over your garage, you may need to hire several other contractors to get the project done.
Architect cost: $2,400–$14,000
Cost to install insulation: $40 to $80 per hour
Drywall installer cost: $1,000 to $3,200
Flooring installer cost: $2 to $25 per sq. ft.
Insulation installation cost: $0.30–$6.75 per sq. ft.
Interior painter cost: $2 to $6 per sq. ft.
Plumber: $45 to $200 per hour
Structural engineer cost: $350–$800
Window installer cost: $300 to $2,500 per window
There are some additional costs you may encounter when adding a room above a garage. The home addition company that you hire should include most of them in your contract.
You’ll need a building permit to add a room above your garage. Depending on your location and local requirements, you can expect to pay anywhere from $140 to $2,500 for a general construction permit, which should cover the plumbing, HVAC, electrical, and roofing work that might otherwise need separate permits. If you’re building the addition as an attached ADU and plan to rent it, you’ll also need a rental permit.
In some cases, an existing garage foundation may need to be strengthened to support the weight of a new room above it. Pros will often do this by extending your foundation's depth, repairing damaged areas of your foundation, or adding additional support through methods like underpinning. Foundation strengthening can add $2,000 to $10,000 to the overall cost of your project.
Any inspections that your building department requires will be included in your permit fees, but it’s a good idea to have a post-construction inspection done after the project to ensure the structure is safe. A home inspection costs between $300 and $450.
After a large construction project comes the inevitable cleanup. Excess drywall, flooring pieces, dust, and debris all need to go before you can enjoy your new space. Your contractor should include the cost for cleanup within your contract, but budget an additional $200 to $500 if they don’t.
Adding a room above a garage costs less than building a detached addition in most cases. Building up from your existing garage means you can skip the foundation, which saves you thousands on the cost. You’ll pay an average of $50,000 to add a room above your garage, whereas building a detached ADU or tiny home addition will cost an average of $180,000.
However, you should think about more than just the cost when deciding. If you’re renting the added space or saving it for long-term guests, building over an attached garage will give you and your guests less privacy than you’d get from a detached ADU. You’re also more limited in the square footage you can add above a garage, while an ADU gives you more freedom to customize.
"Post-pandemic, many people do appreciate the idea of having visitors and the flexibility to work from home in a separate area of the house. A private location near your primary residence for quiet time or remote work is ideal for work-life balance."
— Elizabeth Altobelli, Luxury Properties Specialist with William Raveis - Connecticut
Building a room above a garage is not a DIYable project, so you should leave this one to a professional who builds home additions. Building a garage requires specialized skills and knowledge in architecture, structural engineering, electrical work, and plumbing. It also involves intricate tasks like pouring concrete foundations, framing walls, installing roofing systems, and connecting utilities, most of which your building department won’t let you do yourself legally.
However, you can DIY some finishing touches to save money on labor. Consider installing and painting the drywall yourself or installing flooring, which are more DIY-friendly projects associated with building a room above a garage.
While it can seem financially overwhelming at first, there are a few things you can do to help lower the cost of adding a room above your garage.
Compare quotes from at least three different home addition companies to find the right pro for your job.
Consider what you’ll use the space for, and if possible, avoid additional costs like plumbing.
Take on some of the DIY-friendly portions of the overall project, like interior painting.
An above-garage addition can boost your property value with an ROI ranging from 60% to 80%, with an average of 69%. This is due to the increase in livable square footage and the added value from an additional bedroom, which future home buyers will undoubtedly enjoy. The bump you’ll see depends on the type of space you install.
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A new space over the garage offers several upsides, including added living space, more storage space, and boosted home value from the addition. If you create an attached ADU with the space, you could secure more privacy for you and any guests you have, or even some rental income if you rent the area. However, there are some drawbacks to consider, too, including the high up-front cost, the potential need to increase structural integrity, and size restrictions since garages are smaller than an entire floor of your home.
Not all garages are structurally designed to support the weight of a room above, so the answer depends on a few things. A critical first step is consulting with a structural engineer or building professional to assess the project's feasibility. Your home addition pro will assess what kind of foundation reinforcement will be needed to build the additional space you desire.
As with most large-scale home renovation projects, you’ll need an architect to map out the exact layout and specs of your above-garage room, which is required in many municipalities. Some general contractors will serve as your architect, or they may bring on a residential architect to assist with the plans.