Can I Dig Below My Basement?

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Digging below a basement sounds complex. If you are curious to know if it is possible, then we are here to help. We have consulted with the experts and unraveled the following findings.

It is possible to dig beneath your existing basement. Before you proceed, you need to answer the following questions to help you decide if you should go ahead with the project or not:

  • Do you have extra space for expansion?
  • Is your basement dry or wet?
  • How near are your neighbors?
  • Is there enough access for digging equipment to reach your basement?
  • How low are the sewer lines?
  • What are the cost implications?

After you answer the above questions, you will be able to make a credible decision and move on to undertake the project. Continue reading as we discuss more on how far down you can dig, the cost, and the value additions to your basement.

A nicely refurbished basement room with white painted ceiling, recessed lighting and wooden flooring, Can I Dig Below My Basement

Assessments Done Before Digging Further Down Your Basement

The number one reason most homeowners dig up their basement is usually to increase the ceiling height or the space in general. But before you embark on doing so, you need to assess the situation critically as follows:

Do You Have Extra Space For Expansion?

Digging lower than your basement is not a cheap affair. That is why if you have other options like adding another floor above your home or building another room on the ground adjacent to the house, that would be a better idea.

However, if expanding your basement is your only option, then digging down is a good decision.

Is Your Basement Dry Or Wet?

This is a crucial point that cannot be overlooked. Building a new foundation wall is not a very big issue, as you can easily build a remarkable waterproofing system.

But if you have to create a new foundation inside the current one, then the task will be more complicated as you may encounter issues with waterproofing, making this an unfavorable approach. Talk to a basement professional who will advise you accordingly.

How Near Are Your Neighbors?

It is possible to dig down even when you have close neighbors, though it may be complex and expensive. A shoring system like that used to hold up the walls in the pits dug up for skyscrapers would be required to prevent your neighbor’s house from caving into yours.

If you really must do this, then You may have to request an easement from your neighbors, which may end up being costly because of repairing the fence or the landscape that is interfered with due to excavation.

Is There Enough Access For Digging Equipment To Reach Your Basement?

Your job can be much easier if you have a ramp down your basement to move a mini-digger inside for digging out the soil.

In many urban homes, the setup does not allow easy access, and therefore a conveyor belt, and workers with shovels would be most ideal.

How Low Are The Sewer Lines?

Find out how low your sewer lines are to avoid damaging them when digging out your basement, as it could add to your costs.

What Are The Cost Implications?

This could be your most important point. Whereas there may be factors that could lower your costs, overall, it will be expensive to dig under your house. Stay with us, as we delve into costs in just a bit.

How Deep Can I Dig Under My House?

After you have answered all the questions above and decided you will go ahead and dig up your basement, the next point to decide on; is how far down you can dig.

This will largely depend on the reasons which mainly include adding a basement ceiling and turning a crawl space into a full basement. Adherence to building codes may be necessary, hence permissions from the authorities may be required.

Let us delve further into the reasons for digging down your basement.

Adding Ceiling Height

The International Residential Code (IRC) states that the space in a livable basement should have a floor-to-ceiling height of at least seven feet overall and at least six feet to accommodate bathrooms. The different States may have varying code requirements. 

So, if your basement does not meet these specifications you have the option of lowering the floor, which involves digging between 14 and 16 inches to add six inches of concrete floor. 

Turning Crawl Space Into A Full Basement

Digging out a crawl space to turn it into a full basement is very involved, and requires excavating close or up to six feet down. This means a new foundation will require an extra four to six feet of concrete walls.

Is The Foundation Below The Basement?

A foundation partly holds the weight of your home. It serves the following purposes:

  1. It shares the weight of the house with the ground underneath, avoiding unnecessary overload on the soil.
  2. The house is held in place by the foundation, anchoring between the ground underneath and the frame such as ceilings and walls. This helps your house to remain firmly on the ground in adverse weather conditions such as wind, frost heaves, and floods, and also during natural disasters, such as hurricanes, earthquakes, and tsunamis. 
  3. A foundation that is properly laid down will help provide protection against water from the ground. 

To find out if your foundation is below the basement or not, let’s look at the three types of foundations below:

Basement Foundation

Reinforced basement foundation with gravel base

A basement is actually a type of foundation and is common in many homes. They are constructed by creating a hollow downwards, usually between six and eight feet, depending on the type and condition of the soil.

Crawl Spaces

A worker checking the pipes under the crawl space of the basement

This type of foundation creates sufficient space to crawl in but not stand, and can be raised from one to three feet above the ground.

It is found mainly in humid climates, where homes are raised above the ground avoiding the dampness of the soil. These spaces are not habitable, instead, you will find utilities such as water pipes and electrical wiring.

Though not encouraged, some homeowners store items here. This is because the moisture may end up destroying your stuff especially if the items are paper or stored in boxes made from cardboard.

Slab Foundation

Concrete basement flooring with excess pipes for the waste line and water line

This type of foundation is not dug into the ground. It is simply formed by pouring concrete on the ground to form a slab. However, it does not provide good stability to a home like a crawl space or basement would.

How Much Does It Cost To Dig Deeper In A Basement?

Generally, the cost of digging deeper into a basement varies depending on factors, such as the depth required, the room size, the landscape, location, and easy access to the location.

By and large, the prices range between $10,000 and $100,000 to dig deeper into a basement, while per square foot the price is expected to be from $30,000 to $75,000. The costs can be this high because of the excavation methods that can be very expensive, such as underpinning, and the structural changes that are made to a property.

Concrete slabs normally cost between $4,500 and $12,000, which is significantly cheaper than building a basement or crawl space.

Is It Worth Digging Out A Basement?

If you have space in your basement that you turn into a livable space, it definitely will be worth it. Despite
the initial high costs, in the long-run you will enjoy a higher ceiling and much bigger space, in your basement for a long time.

Furthermore, a finished basement will add value to your home by 70% to 75% of the investment you make. For example, if you spend $1,000 on improving your basement, your home will have an added value of $700 to $750.

In Closing

A nicely refurbished basement room with white painted ceiling, recessed lighting and wooden flooring

It is possible to dig deeper into a basement, but before you go ahead, you need to go through a few factors to determine how feasible the project is; some of which include how low the sewer lines are and the costs involved.

After verifying the factors and concluding your project is possible, how deep you will go down depends on the purpose for which you are digging the basement. The basement can actually be the foundation of your home. Also, crawl spaces and concrete slabs are other types of foundations.

Have a look at our other posts that show you how to finish a dirt basement, and learn the difference between a basement and foundation:

Can You Finish Dirt Basement?

Difference Between Foundation And Basement

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