Lowering Your Basement Floor: A Complete Guide6 min read

A basement can be used strategically to provide additional living or storage space for a home. However, some basements have a limiting factor that greatly reduces their practical usefulness: inadequate headroom. So, how feasible is it to lower your basement floor?

Before lowering your basement floor consider: the cost, local building codes, the time required, and how to address lighting and ventilation in the renovated space. Then, decide whether to use foundation benching or underpinning. The total cost will likely be at least $10k.

Lowering your basement floor is a complex process, but it offers many benefits. Let’s take a closer look at the details of lowering your basement floor so that you can decide if it’s the right choice for your home.

Why Would You Want to Lower Your Basement Floor?

There are several reasons why someone might choose to lower their basement floor. Let’s look at the most common reasons:

To Create Additional Living Space

Your basement can serve just about any purpose. One such option is creating additional living space. But why would you need to lower the basement floor to do so?

The average ceiling height in residential buildings is typically around 8 feet, although it can range from 7 to 9 feet. The standard was established for practical reasons, such as accommodating the average person’s height.

Another consideration is accommodating furniture and providing more space for heating, ventilation, and air conditioning systems. 

Note: depending on the technique used to lower the basement floor (covered later) you may also lose floor space.

But before turning your basement into additional living space, you should be sure to take the following considerations into account:

  • Ensure your basement meets local building code requirements, including minimum ceiling height, windows, and fire safety features.
  • Basements are prone to moisture, so address any issues with waterproofing, ventilation, and drainage.
  • Your basement may not have enough natural light, so consider adding artificial lighting and electrical outlets to meet the needs of a bedroom.
  • Basements can be drafty and colder than the rest of your home, so make sure to add adequate insulation to keep the space comfortable.
  • Consider the type of flooring that will work best in your basement, such as concrete, carpet, or hardwood.
  • Ensure easy and safe access to your basement bedroom, such as a staircase or a finished landing.

To Add Value to the Home

A well-designed and finished basement can increase the overall value of your home and make it more appealing to potential buyers if you ever decide to sell. 

PunchlistUSA predicts a 75% return on investment for homeowners in the US who spend on finishing their basements. Not a bad return considering the living benefits available, too.

A finished basement adds extra square footage to your home. That, in turn, provides more space for a family to live and work. A basement can be used as a family room, home office, gym, playroom, or extra bedroom.

In addition, a basement can provide additional storage space for belongings, helping to declutter the main living areas.

Insulating your basement and adding a vapor barrier can help to improve your home’s energy efficiency and reduce heating and cooling costs. The process is more efficient in a larger basement. That is a huge selling point if you decide to put your house on the market.

You can design your basement to include features such as a home theater or a laundry room, adding additional functionality and convenience to your home.

Things to Consider Beforehand

Regulations

Ensure that the new ceiling height meets local building codes and regulations, including minimum height requirements and fire safety codes. 

Note: building codes vary state by state. Seattle demands habitable basements be over 6 feet 8 inches, whereas California asks for at least 7 feet.

Not adhering to such regulations can land you in legal trouble. But again, a construction professional can advise you on this.

Ensure that the existing structure can support the weight of the new ceiling. It may require adding additional support beams or posts. Again, you will need a professional to determine whether this is an issue. 

If so, you will need to build the reinforcements and make structural adjustments. For this, you should consult an architect or structural engineer.

HVACs and Ventilation

Then there is the matter of HVACs and ventilation. Consider how the changes to the ceiling height will impact heating, ventilation, and air conditioning systems.  

You will also need to consult an electrician to check if your plans will impact existing or planned electrical fixtures. 

You will also need a plumber to check whether lowering your basement floor may impact plumbing fixtures.

Lighting

Plan for adequate lighting, including ambient and artificial lighting, to ensure the basement is well-lit and functional.

Bigger spaces need more lighting. Therefore, lowering your basement floor impacts the efficacy of any lighting you may have previously installed.

Cost

Lowering a basement floor can be a significant investment. So, budget appropriately and compare quotes from multiple contractors to ensure you get the best value for your money. 

h2ouse.org estimates lowering a basement floor to $350 to $450 per square foot. The average size basement in the USA is 500 square feet – 1500 square feet.

While opting for the lowest quote is tempting, carefully consider what each contractor includes in their quote. There’s nothing worse than having to hire a second party to fix the mess made by an incompetent contractor.

Time (and disruption) 

Lowering a basement ceiling can be time-consuming, so plan accordingly and allocate sufficient time for the work to be completed. Typically basement lowering takes around 3 weeks to complete, but this greatly varies based on the size and scope of the project. The two main techniques – benching and underpinning – also impact the project time. Benching is more efficient and quicker than underpinning (I explain the differences in detail later).

It’s also worth noting that when most households have their basements lowered, the residents will temporarily move out. As this is considered major construction, there will be lots of dust, jackhammering, and drilling. Whilst it is technically possible to live in the house whilst the works are carried out, I wouldn’t recommend it.

The Future 

Consider any plans for your basement, such as adding a bathroom or converting it into a living space. Ensure that the new ceiling height doesn’t interfere with these plans.

So many little details can come back to present a problem for future work on your home. For example, it could mean that adding plumbing or additional building is made nearly impossible. 

Methods for Lowering a Basement Floor: bench footing vs underpinning

The two main methods for lowering a basement floor are bench footing and foundation underpinning. Bench footing is less invasive and involves lowering the existing concrete floor by 15cm – 30cm. Underpinning is more expensive and complex and involves digging under the existing foundation.

Which method is right depends on the specific requirements of your project. That includes the size of the space, the existing floor structure, and your budget. Bench footing is cheaper and more efficient, but if you’re wanting to achieve more than an additional 30cm of headroom then underpinning is the option.

It’s important to consult a licensed contractor or structural engineer to determine the best method for your basement and ensure that the project meets all relevant building codes and regulations.

Bench FootingUnderpinning
Faster, less invasive and cheaperMajor construction work, takes longer and is expensive
Loses square footage due to the ‘bench’No square footage lost
Limitation of only adding up to 30cm of headspaceTechnically can be done up to 15 feet
No need to get neighbours permission Can disrupt neighbours soil under foundations of shared wall
If foundations are older and weaker, bench footing may not be possibleStrengthens existing foundations and can be used for upgrades

bench footing (or foundation/basement benching)

Bench footing (AKA Basement benching) is the most cost-effective way to efficiently add ceiling height to your basement. One misconception is that bench footing involves simply digging the existing floor downwards, but this would result in the house collapsing. 

First, a bench is built around the interior walls of the basement, and then the basement is lowered within the benched space. Then a lower concrete slab (the floor) can then be poured at a lower depth without modifying the walls. There’s also the need for builders to remove excess water which is created by digging deeper. 

Bench footing in basement
The red areas in this photo shows where the bench would be built.

Since Bench Footing is not very invasive, homeowners probably don’t need the permission of next-door neighbors to carry out this work. But always check your local building codes to be on the safe side.

As mentioned, bench footing requires far less digging and is less invasive than underpinning, making it a lot faster and cheaper to complete. However, there are two downsides: 

  1. The maximum amount of additional head height is around 30cm. This is due to limitations on extending the foundation through a bench rather than digging a new one. 
  2. The formation of the ‘bench’ reduces square footage. It’s basically a bench around the perimeter of the basement. Many homeowners will turn this bench into some kind of feature rather than letting it become wasted space. 

Foundation Underpinning

Underpinning is a detailed process that involves excavating a series of holes below the current foundation footing, and gradually filling them to reinforce and lower the footing. In layman’s terms, underpinning is removing existing basement footings, excavating to a lower depth, and then pouring new fittings. This is different from benching which is more like extending the current basement footing. 

Three advantages to underpinning are: 

  1. Underpinning strengthens the foundations of the home as well as creates additional space. This may be required to modernize your foundations to be in line with new building standards. This is particularly relevant for older homes with old foundations. 
  2. If foundations are in need of repair, underpinning can also be used for this purpose. If foundation cracks are present, it may make sense to kill two birds with one stone and also have your basement floor lowered. 
  3. Unlike Bench Footing, with underpinning you don’t lose any square footage area.

Underpinning takes longer than bench footing and requires specialist contractors. In addition to disruption, the other major disadvantage of underpinning is the cost. Project costs vary but you’re likely going to spend $20,000 to $50,000. 

However underpinning would be the best choice if budget isn’t at the top of your priority list, or if your current foundations are not strong enough for bench footing. 

Choose to underpin if the foundation is not strong enough, if you don’t want to lose square footage, and are not concerned with the cost.

Lastly, with underpinning typically you’ll need permission from your neighbor where you share a common wall. This is because when excavating, the soil under the foundation of your neighbor will be affected. 

What’s the Average Cost of Lowering a Basement Floor?

The cost of lowering a basement floor can vary widely depending on the specific requirements of your project. Some common factors that can impact the cost include the space’s size and the complexity of the work. 

In addition, one must account for the cost of labor and materials.

On average, you can expect to pay anywhere from $8,000 to $60,000 or more to lower a basement floor. However, the actual cost will depend on the specifics of your project. 

Getting detailed quotes from several contractors is important to ensure you get the best value for your money.

Keep in mind that additional costs might be associated with lowering a basement floor. These include the cost of permits, plumbing, electrical modifications, etc.

Understanding the Building Regulations in Your Area 

Building regulations exist to ensure that buildings are safe, accessible, and meet minimum standards for health and safety. Failing to comply with building regulations can result in fines, legal penalties, and the need to make costly changes to your project.

Regulations vary by jurisdiction. Therefore, it’s important to understand the specific regulations in your area before beginning a renovation project, like lowering a basement floor.

To find the building regulations in your area, you can start by searching online for your local building department’s website or contacting them directly.

Common Building Regulations:

Some of the common regulations that you may encounter include the following:

  • There may be minimum ceiling height requirements that must be met, typically 7 feet or 8 feet, to ensure that the space is livable and meets fire safety codes.
  • Regulations may specify the maximum load a floor can support, which can impact the materials and construction methods used. 
  • In addition, there may exist requirements for fire-resistant materials and construction methods.
  • Regulations may specify the minimum levels of ventilation and air circulation in a basement to ensure that the space is healthy and safe. 
  • Regulations may specify the minimum size and location of windows and doors to ensure that occupants can evacuate the basement in an emergency.
  • Regulations may also specify the type and location of electrical and plumbing fixtures, such as outlets and pipes, to ensure they are safe and accessible.
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Hi, I'm Ed, and I run BuildFanatic! I enjoy providing the best possible information on a range of home improvement topics.

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