Basement Underpinning – Features, Benefits & Stages

Here we’ll be discussing all you need to know about basement underpinning, so keep reading.

There are a few good reasons for homeowners to underpin their basements. The process can be used to turn a crawl space into a usable part of the home, to fix an unstable foundation, to support the foundation, or to boost the foundation’s weight capacity.

It is an old practice that has been used to fix many basement support problems, and if you’re wondering what it encompasses, then you’re reading the right article.

What Is Basement Underpinning?

For those who don’t know, basement underpinning is the practice of excavating soil from underneath a concrete slab or crawl space, then re-enforcing the space with new concrete footers, walls, and floors for the sake of creating a more stable and rugged foundation.

This job is very tedious and can only be done by very experienced professionals.

Before proceeding, the pros will first do a thorough evaluation of the structure and its immediate environment to be sure of what would be required to begin and finish the job.

Factors such as building code requirements with regards to depth of excavation, the amount of concrete work to be done, as well as electrical and plumbing re-routing will all be taken into consideration.

Is Underpinning A Basement Really Necessary?

Most professionals will tell you that the number one solution to subsidence is underpinning.

As we have pointed out before, the process involves a lot of excavation beneath the concrete walls and adding a great amount of concrete for support.

Such a process cannot be carried out by quack basement underpinning contractors, and it would definitely cost a lot of money. This is why many homeowners only embark on the process when they seem to have no other choice.

New buildings may not require underpinning, but the same may not be said of old houses.

This is because the parts of an older building that haven’t been underpinned will continue to move naturally following the soil conditions.

So if you’re considering underpinning, be sure to thoroughly investigate and find out why there is subsidence in the first place.

Stages Of Underpinning

If you’ve made up your mind to underpin your basement, then below are the stages you should expect the contractor to pass through.

  1. Designing The New Space

Once the initial evaluation has been done, the underpinning contractor in charge of the project will have to design the new space. The new plans will have to be submitted to the local municipality so they can be approved.

You will receive a permit after that and the underpinning work can commence.

  1. Preparing The Site

Once the permit has been received, the next step would be to prepare the area for the construction work. This involves re-routing furnace connections and installing temporary support to keep the building in place during work.

Steel beams and wooden boards are used to hold the building steady while the work is ongoing. They are eventually removed after the job has been completed.

  1. Lowering The Basement

When it comes to shallow underpinning, the traditional mass method is employed.

In this case, the soil beneath the foundation isn’t thick enough to support the top structure, so it is excavated and replaced with a mass concrete filling.

Doing this will strengthen the bottom soil and ensure a more even weight distribution.

The beam and approach use the traditional mass base, but with the incorporation of hard concrete beams. This is built right below the concrete base so that the load can be evenly spread across and enhance support.

There’s a third approach that can be used, and this is called the mini-piled underpinning. This method allows the structure to sit on a stable and sturdy base about 5 to 15 meters under the new footers.

Piles of about 15 to 30cm are built and housed in a steel casing. Then they are driven into pre-drilled holes so they can sit on a more rugged ground base.

Another aesthetical approach for basement underpinning demands that the already-existing concrete floor be taken off. Here, the soil is removed in parts, then replaced with concrete.

Small gaps will be left between the new and former concrete. After that, the areas of each part are filled with non-shrink grout.

The Right Finishing

After the underpinning is completed, waterproofing foundation walls and sump basins can be installed. The type of underpinning method used doesn’t matter, the old plumbing should be uninstalled and replaced with a new one.

To ensure the structure stays dry for as long as possible, you must install a proper basement waterproofing system. As we have mentioned earlier, an expert basement underpinning contractor is in the best position to execute a job of this nature.

A waterproofing system ensures that water will not be able to penetrate the basement from the exterior. The contractor should ensure that the exposed foundation walls are backfilled.

Now that the exteriors have been waterproofed, it’s time to do the same for the interior.

An internal weeping pipe can be placed around the room’s perimeter below the floor level. This will collect the groundwater and redirect it to the new sump pump, which will then carry it outside.

The entire floor should be covered with a layer of gravel, which offers a secure base for the brand new concrete floor.

This is quite an extensive project to carry out, which means it would take a good amount of time to complete. At every stage, adequate time must be given for the concrete pour area to cure.

Doing this will ensure adequate tensile strength is achieved before the temporary supports are taken off.

Keep in mind though, you and your household may experience some inconvenience during the duration of the work. However, expert contractors should ensure that it is carried out with minimal disruption.

The contractors should also ensure that there is no damage to your home while work is ongoing. This is why you need to hire trained and experienced hands for the job.

You can go online to find one, also check out their testimonials to see what people are saying about them before you commit.

Benefits To Underpinning Your Basement

 Underpinning your basement can be done for a good number of reasons. The major ones include –

  • Stabilizing your home from structural damage
  • Expanding the current living space

Below are other benefits of underpinning your basement.

  1. It will make your home more accessible

After any form of construction or reconstruction is carried out in the basement, it potentially opens up the hidden aspects of your house. This will make your home easily accessible when you want to carry out inspections or repairs.

If your house is old, underpinning provides the opportunity to modernize your home by taking out the old plumbing and replacing them with more modernized installations.

Old wires and electrical connections can also be replaced with newer ones. New insulation systems can also be installed.

To add to that, underpinning also gives you the chance to upgrade your waterproofing systems and spare your basement from future leaks and water damage.

This will in turn help you save money in the short and long term on structural damage caused by water.

  1. It offers the chance to increase ceiling height and increase space

Basements in old buildings usually have low ceilings which makes you feel too boxed in. However, underpinning gives you the chance to increase the height of your ceiling, which will create a more comfortable living area.

The process also gives you the chance to tear down any unwanted walls and turn your basement into whatever you want. If you wish, you can build a new game room, an extra bedroom, or even a home theater.

  1. It gives the chance to remove any already-existing structural problems in the foundation

It is common for foundations to experience structural problems now and then. This is mainly caused by leakages, bad weather, soil types, and even bad jobs done by inexperienced contractors.

Underpinning gives you the chance to correct these deformities and ensure you have a more solid structure in the foundation.

Making your home structure more solid improves the overall value of the property, and this will allow you to lay down a higher asking price if you ever decide to sell.

  1. It can be a low-cost project

If you’re underpinning your basement purely for the sake of basement expansion, then it can be very inexpensive to do.

In this case, all the work is being done only in the basement, so the other parts of your house will not be affected, and you can carry on with your daily family routine.


Boosting your foundation’s weight capacity, fixing structural damage, and expanding the space are among the several reasons homeowners underpin their basements.

It has its advantages, so you can embark on it if the situation requires you to. It’s a really technical job, so remember to hire only the best hands to do it.

Thanks for reading!

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