Can You Build A Basement Under A Garage?

It is certainly possible to build a basement under an existing garage; however, there are many pros, cons and caveats to consider with this project. Generally speaking, you are far better off constructing the basement first and then adding the garage. In this article, we discuss the options and provide tips to help you decide how and if you will build a basement under your garage. Read on to learn more.

When You Build Your Garage, Plan For A Basement

When You Build Your Garage, Plan For A Basement

Adding usable square footage to your home without expanding its footprint is always desirable.

But if you plan to have a basement under your garage, you would be very wise to have a flexicore or hollow core floor installed rather than counting on your poured concrete floor to keep your car from plummeting into the middle of your newly created space.

As this video makes clear, installing this type of flooring is a lot more easily done at the time of construction than after the fact.

For the best, most reliable and most usable garage basement, it is wisest to install a prestressed, hollow core precast garage floor made of slabs that have been especially engineered and manufactured for that specific space before you ever begin building a garage.

This type of flooring is installed on a pre-built shelf and needs no support beams. This is the kind of construction that is used in commercial parking garages for maximum durability and safety.

Furthermore, when you use hollow core floor panels, you don’t sacrifice any space to support structures. You’ll be able to make use of all of the space below your garage.

Even though use of this type of flooring requires meticulous planning and is significantly more expensive than traditional garage flooring made of stone that has been finished with smooth concrete, the planning and expense are worth it.

The hollow tubes built into the planks significantly reduce the weight of the flooring, while simultaneously increasing strength and reliability thanks to built-in steel beams.

Is It Smart To Put A Basement Under Your Garage?

When it’s done right, a basement underneath the garage can add lots of usable space and great value to your home. When it’s done wrong, it is a mess at best and a catastrophe at worst and may significantly decrease the value of your home.

If you are not able to pre-plan your garage basement and make it part of your original construction, you must be extremely careful and meticulous in every step of the planning and building of your garage basement.

Building a basement under your garage is not a do-it-yourself project because there are a great many factors you must take into account. Ask yourself the following six questions:

Can I get the help I need for this project?

You will need a very skilled and experienced certified contractor and engineer to design and carry out this project safely. Do you have access to that kind of assistance? Can you afford it?

Can I get a permit to dig a basement under my garage?

Check your local building codes. You may not be able to get a permit, or it may be more costly or difficult to get a building permit for a basement than for some other sort of addition.

Will I be able to get insurance for a garage basement?

Check with your insurance agent. It may be very expensive or even impossible to insure your structure.

Is there a viable alternative to digging a basement?

Could you add a story above your garage or build a space to the side? Either of these projects would be easier and less costly than digging a basement.

Is the space this project would provide worth the expense?

It can be extremely costly to add a basement under your garage, depending upon where you live and how much it costs to hire skilled assistance.

If you live in a location where property is expensive and extra living and storage space is rare, the cost may be justified by the amount of value a properly constructed garage basement will add to your home.

Do I have the time this project requires?

Building a garage basement can take a very long time because it requires a lot of planning. You may have a hard time finding a truly qualified professional to help you, and it may be difficult to get the needed materials.

Furthermore, the construction itself must be done in a painstaking and meticulous manner for safety and stability.

Would buying more property be a better investment than building a basement?

If it’s possible to buy the lot next door or across the alley and build more usable space onto it, it will be a better investment than building a basement. True, your initial outlay of cash will probably be greater, but in the long term, your money will be better invested than it would in digging a basement.

Moving Forward With Your Garage Basement Project

Moving Forward With Your Garage Basement Project

After you’ve examined all the pros and cons on your own, discuss them with a trusted advisor and with a contractor and/or engineer certified to design and build a garage basement.

If you come to the conclusion that building a basement under your garage is the best thing you can do, it’s time to start drawing up plans.

How Will You Use Your Garage Basement?

A basement is a great space to have for a wide variety of uses, such as:

  • Family room
  • Wine cellar
  • Home gym
  • Workshop
  • Playroom
  • Storage

…or whatever your heart desires; however, it‘s important to define those desires. You need to know exactly the sort of space you need before you built it. There is a certain appeal to having blank space to shape as needed, but this is not easy with a garage basement.

Important construction questions to keep in mind include:

1. Do I want to use the garage basement for a living area?

If you want to exercise, watch movies and pursue hobbies in your garage basement, you need to be sure the garage floor above is well sealed to keep out moisture and fumes.

2. Will I want to store heavy equipment in my garage basement?

If you need to bring lawn mowers and trailers and whatnot in and out, you’ll need a ramp. If you also want to use your basement as a living area, you’ll need to construct a wall to keep these two functions separate.

3. Do I want to use my garage basement as a safe room or storm shelter?

This can be a very good use of a garage basement. If this is your plan, remember to have necessary elements such as plumbing, food storage space, etc., built in right from the start.

Identify And Gather Your Resources

Once you have a clear plan, you can begin pricing materials and equipment. Things you’ll need include, but are not limited to:

  • Foundation walls, 1’ thick, steel reinforced for all sides of your basement
  • Flexicore floor panels pre-engineered for your application
  • A crane for lifting and positioning the floor panels

If you plan on installing any pipes, wiring etc., in your garage basement, you must detail it in the plans and get it in place before you install the flexicore. Once it’s installed, it will be firmly attached to the walls. Making any openings in it will be very nearly impossible.

Is A Garage Basement Your Best Choice For Added Storage And Living Space?

If it’s the only choice, and it’s correctly done, a garage basement can bring you all of the advantages of any added storage and living space; however, the fact that it’s such an unusual addition can make it difficult to sell your home.

No matter how well done it is, potential buyers may look askance at it and wonder if it’s really safe.

For this reason, along with the added expense, the difficulty and the amount of time necessary to complete this project, you may very well be better off choosing another alternative for adding storage and living space to your home.

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