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What Is The Cost Of Digging Out a Basement in 2023?

basement under construction

Basements, much like attics, are invaluable spaces in any home. When you need more space in your house, sometimes the answer is digging out your basement. Many “standard” basements have a paltry height of 6 feet, which is very constricting when you want to use your basement to its fullest.

If you’d like to use your basement for more than laundry or storage, a great way to do that is by expanding it. Increasing the height can be just the thing to turn your boring basement into a guest room, home theater, or any number of other options.

There are several techniques available for expanding basements, though underpinning is the most common type. Let’s check out how much it costs to dig out a basement via underpinning, what alternatives are available, and more.

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What Is Basement Underpinning?

Underpinning generally refers to work involving the foundation, but it has another meaning when it comes to increasing the usable space within a basement. Either way, though, underpinning deals with the foundation of your home, which is complex and labor-intensive work.

It involves digging up the floor of the basement, removing the existing footings, and placing new footings at the new floor level of the basement. The critical part of this process is keeping the structure braced while it’s being excavated which is why professionals are needed.

Underpinning your basement stabilizes the foundation, which is a handy benefit, but that’s not all it does: it increases your usable square footage and can hide unsightly aspects of your basement.

Underpinning can hide things like support columns, water heaters, and other nonessential components of the basement. This can go a long way towards turning your basement into a more functional and attractive part of your home.

Digging out your basement via underpinning is a great way to expand your house if you’re unable to build another story or expand outward, and it usually doesn’t disturb other parts of your house.

construction of basement
Image Credit: Andrei Kholmov, Shutterstock

How Much Does Basement Underpinning Cost?

Any modification to your home is going to cost, and underpinning is no exception. The average basement expansion is around 2 feet, giving the whole space more height. Average costs of basement underpinning range from $300 to $450 per linear foot, not to be confused with square feet.

The final cost of underpinning depends on how big your basement is. An 800-square-foot basement expanded from a 6-foot-height to an 8-foot-height can cost as much as $40,000 to $60,000 when finished. This includes additional costs necessary to fully complete the work, which we’re about to talk about in more detail.

Additional Costs to Consider

On top of excavation, there are the costs of pouring concrete, waterproofing the basement, installing a sump pump, and if you opt for it, finishing work. Together, they substantially raise the price of your average basement expansion.

Typical Cost For:

  • Pouring Concrete Slab: $20 per square foot
  • Drainage including Sump Pump Installation: $4,000 to $6,000 (one-time)
  • Demolition: $4-8 per square foot
  • Finishing: Depends heavily on preference

Depending on your basement and your house, there may be other work involved to dig out the basement floor. These can make the job more complicated and costly, not to mention time-consuming.

If you have support beams in the middle of your basement, the contractor will have to install new ones, typically metal beams. If you want a separate entrance for your basement (often called a walkout), that will cost more, too. As a final example, your whole project will cost more if you have limited space for the contractor to work. Limited access means slower work, so they need to charge more to make it worth their time and effort.

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How Long Does It Take To Dig Out a Basement?

You’re looking at 3–4 weeks for most underpinning jobs, not counting extras like finishing the basement or adding a walkout entrance. You should bear in mind that any number of things can delay this figure. If you need to relocate electrical panels, water heaters, or build new stairs, that adds time and money.

Basement Underpinning vs. Basement Benching

Underpinning isn’t the only way to dig out a basement. Benching or bench pinning is a method of lowering your basement that doesn’t dig out the foundation. Instead, the contractor will use “benches” around the perimeter of the basement to marginally increase space.

Finished basements will have a distinct “bench” around the outside, which many people disguise with cabinetry or other storage solutions.

Overall, benching is cheaper than underpinning because it doesn’t touch the foundation or original footings. This can make it an attractive alternative, but the biggest downside is that benching doesn’t add nearly as much space to the basement. In many cases, benching actually reduces the usable square footage of the basement.

Is Basement Underpinning Worth It?

For large homes with large basements, the cost of underpinning can approach the market value of a small home! This makes it cost-prohibitive in cheaper housing markets and more attractive in expensive housing markets. In many places, it’s cheaper to add a story to your home or build a new bedroom.

In some places, it makes sense to dig out a basement. For example, it makes more financial sense to underpin a basement in New York City or Los Angeles than in a small Midwest city.

If a property is worth a million dollars or so and moving to a larger space isn’t possible, it turns out cheaper to dig out the basement. Conversely, you probably don’t want to spend upwards of $50,000 to dig out a basement for a house that’s only worth $250,000.

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Basement underpinning is a great way to get some additional space in your basement, whether you’re creating a game room, den, or home theater. In many cases, it’s cheaper to simply expand up or outward, but basement expansions are most valuable in more expensive cities.

Featured Image Credit: ungvar, Shutterstock

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