Can You Build A Basement Under A Garage?

If you want extra space for more storage, a basement is a great addition to your house. You might wonder if you can create a basement under an existing house structure, like the garage. Such a project will be difficult due to the complex processes. If you are in doubt, we have consulted the experts so you'll know if you can proceed with this unconventional basement building project.

Even though uncommon, you can build a basement under your garage. You can use the basement garage for extra car parking or a workshop. Like every home improvement project, there should always be a plan. Below are the common factors to consider before building the basement:

  • Specific state building code requirements
  • Costs of construction
  • The existing structure of the garage

Even though building a basement under a garage is possible, you also have to weigh the pros and cons. It is best to hire professionals for the technical work to avoid structural damage. Continue reading to learn more about building a basement under a garage.

Background wallpaper concrete stairs concept. basement garage. Can You Build A Basement Under A Garage

What Is A Garage Basement?

A garage basement is where you can keep your cars under the ground. Instead of parking your vehicles on ground level, you can keep them safe under a garage basement. If your house is in some elevated place, it would be great to create a straight driveway.

With regards to construction, you have to consider the type of soil on your lot. Then you can choose which type of foundation is best for your garage basement. You can consult a foundation professional for advice. Of course, you have to follow the legal requirements of your state building codes.

Read further for some ideas you can do with a garage basement.

Uses Of A Garage Basement

A garage basement is not only for your vehicles, but you can use the space for other activities. Your basement garage can be your workspace or just a hideaway where you can rest and relax.

Other uses of a garage basement include the following:

  • Make the garage basement your car workshop. You don't have to go away from home to work on your cars.
  • You also can store seasonal equipment and tools like lawnmowers and snowblowers.
  • Convert the garage basement as your workout area or a recreation room.
  • Ideal storm shelter because of the strong foundation and walls surrounding it.

Once you finalize what you want to do with your garage basement, you should also consider the benefits and drawbacks of building one.


Whenever you plan to build a basement, you should always look for the benefits. You have to remember that your garage basement should also be functional like other parts of your home.

Here are some benefits of creating a garage basement:

  • Extra storage or living space.
  • Leaving more space for your outdoor areas.
  • Clear separation from the main house.
  • Excluded in computing for the floor area ratio (as long as the intended use of the garage basement is for parking).


While building a garage basement has its benefits, here are some drawbacks:

  • You have to deal with issues like flooding and insulation.
  • If you have several cars, you should consider if the upper garage floor can carry their weight.
  • There is a need for a ramp or stairs to go up easily. It may be difficult for you to carry your groceries from the garage basement going upstairs.
  • If you plan to sell your home, the resale value may be lower.

What Is The Difference Between A Basement Garage And A Built-In Garage?

Both the basement garage and built-in garage are functional spaces where you can park your vehicles. The main difference between the two garage types is their location.

A basement garage is partially or fully below the ground level. In contrast, a built-in garage is on the same level as the main floor of the house.

A built-in garage is an attached garage where you can access other rooms in the house. Unlike a basement garage, the only way out is the upstairs garage door.

With access to the main home, car fumes can quickly transfer inside your house. If you have loud tasks while in the garage, the noise will disturb the household.

In terms of design, you can follow the style of the main house for your built-in garage. You have to make your garage appealing to the neighborhood because it becomes a focal point along with the main house.

It is great to match the garage doors, trims, and windows with the main home to get a cohesive look.

After all, the type of garage you plan to construct should align with your family's needs.

How Much Does It Cost To Build A Basement Garage?

In every home project, you should account for your costs. You have to make a detailed budget to avoid overspending. You can account for the materials, labor and professional fees, and other legal requirements with a budget.

It would cost you around $48,000 to $80,000 to build a basement garage. However, the costs can still go over this range.

The costs depend on the size, connections, and finishing touches of the basement garage. If you are into a modern underground garage, you can even install an elevator lift.

There are legal requirements that you should also follow. Some states require fireproofing a basement garage. One method is by installing fire stops between basement ceiling joists and drywall. You should also install safety and security measures like smoke detectors and door locks.

Read more about Maryland's garage and basement fire safety. You can refer to your state fire department for their specific requirements.

You have to select the best for your basement garage to avoid frequent repairs. You should be able to get more benefits in the long run to justify the costs. Do not take the risk of building a basement garage if you cannot afford the costs.

Do I Need Planning Permission For A Basement?

Before you can finally build a basement under your garage, you must comply with the legal requirements. You will need planning permission if you meet the conditions listed below:

  • The earthworks for your basement garage exceed the total gross area of your house and at least 50 percent of the backyard area.
  • Suppose you are planning to create a basement garage with two or more stories. You could not build additional floors over an existing basement even if you have a previous development permit.
  • The basement elevations (if any) should not obstruct the street view of the main house. Otherwise, you will need a planning permit.
  • Your house is in a conservation or protected area. You have to apply for a planning permit before you can get a building permit.
  • You live in multi-family residential units or social housing communities. There might be provisions in the title that prohibits modifications and additions to your house.
  • If you are in a flood-prone area, you have to get a planning permit after the approval of the basement building proposal. You should have a detailed plan on how to mitigate the flooding with the help of a professional.

You have to go through detailed and complicated assessments to abide by state laws. The basement construction must be legal so that if issues arise, you won't have to worry much. It would also benefit you if you have any insurance claims and for future home appraisals.

Abstract empty basement parking lot interior with dark gray concrete walls and white ceiling lights

In Closing

You can build a basement under your garage. With a basement garage, you can park your cars underground. Aside from the usual function, you can also use the basement as an extra storage or recreation room. You can be creative about what you want to do with your basement garage.

If you plan to make one, you should be ready for the costs. It is costly to create a basement under your garage. You have to account from the preparation to finishing. Aside from the costs, make sure that you have the permits to begin the construction. If you are all set, build your basement garage now!

You can read more about building a basement from our previous posts:

Can You Build A Basement Under An Existing House?

Can You Add A Basement To A House On A Slab?

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