Skip to Main Content


Underpinning is used by contractors to fix settling foundations. But will it get the job done?

Get a Free Estimate

Replacing doors and windows, fixing a leaking roof, painting the walls, or putting in new flooring are just some of the projects that come to mind when someone mentions house maintenance. However, the most important structural element of your home is not that visible. You might not even notice that something is wrong with it until it is too late. We are talking about your foundation, the part of your home responsible for its structural stability.  

If you neglect your foundation and don’t react to the first signs of trouble, you could end up with a home that is slowly sinking into the ground. In addition, you might have to deal with insect or rodent infestation, which is never pleasant. If your foundation is cracked, tiny creatures can easily squeeze their way into your home. This should especially concern those with crawl space foundations. On the other hand, when there are foundation issues, plumbing in your home becomes very vulnerable. The shifts in your house can cause plumbing pipes to break, and sometimes the levels of the damage can be catastrophic. A damaged foundation can also lead to mold and mildew issues. These can create a toxic environment for you and your family. 

One of the reasons why your foundation can become damaged is changes in the soil. If your home was built on unstable soil that often shrinks or expands due to different weather conditions, your foundation will need to be reinforced. Otherwise, it could settle or crack, causing the problems we mentioned earlier. Luckily, some methods can easily solve this problem. Let’s take a closer look at underpinning and what this process includes. 

piers for underpinning

What Is Underpinning? 

Underpinning is the process of strengthening the foundation of a house, a building, or some other structure. It often involves extending the existing foundation so that the weight load is evenly distributed across a greater area. The first step of underpinning includes the excavation of soil that is located directly under the foundation. The dug-out soils are removed in stages, to lower the risk of undermining the foundation and therefore causing structural problems. This is a major repair project, and a foundation repair professional needs to calculate the depth of excavation by taking the type of soil into consideration and identifying the layers that can hold the load. Once a layer of the soil has been replaced with an underpinning material, the process is repeated with the next layer. This procedure goes on until the complete structural base is finally reinforced. 

Reasons for Underpinning 

There are several reasons why homeowners decide to underpin their homes. Some realize that their foundation is no longer able to bear the load of the house, or their home has changed in some way. Then, some find the soil properties weren’t calculated when the foundation was being built. Sometimes, the purpose of a structure changes and underpinning comes after major renovations. In some cases, underpinning is needed when the structure nearby is being built and the construction includes the excavation of the soil that holds the foundation. Some homeowners want to expand their homes by adding another story. In this case, the existing foundation won’t be able to hold the added load and therefore will need to be underpinned. Certain events like natural disasters can affect the soil and make the structure unstable, so underpinning is required. 

Types of Underpinning 

While there are various methods of underpinning, one type stands out above the rest. When they want to reinforce the foundation, repair contractors will opt for a more permanent pile method. This method is used when the foundation sits on unstable soils, while firm soil layers are situated at substantial depths. In this case, the foundation piles or piers are installed evenly along the foundation to transfer loads from the existing foundation to the piers and to potentially lift it.  

Temporary Underpinning Solutions 

There also are various underpinning solutions that can be used by professional repair crews. Some common methods that have been used in the past may have worked at the time, but these are only temporary fixes at best. 

Concrete Underpinning: The problem with this method is that it doesn’t address the unstable soil. It involves excavating the soil around the foundation and then pouring concrete under the existing footings. This way the footing is extended. When the concrete is dry, the soil is backfilled. 

Concrete Piers: Concrete piers are concrete cylinders that are connected with a wire. These are driven into the soil, but since there is nothing to guide them, they cannot go deep into the ground. 

Durable Underpinning Solutions 

If you wish to permanently fix your foundation problem, here are different, more reliable methods you can opt for. 

Push Piers: These piers are the most commonly used type of piers and their purpose is to permanently stabilize the foundation, prevent it from settling, and potentially lift the foundation back to its original position. They are made from galvanized steel so they will not rust or corrode. 

Helical Piers: Helical piers are designed to reinforce the foundation just as push piers are, except that these are screwed down mechanically into the ground. They are used to support the foundation of lighter structures such as porches and chimneys. 

Slab Piers: When a home is built on a slab foundation, contractors use slab piers to strengthen the foundation. 

If you have noticed that something is wrong with your foundation, contact AFS Foundation & Waterproofing Specialists and schedule a free inspection. We provide our services in Georgia, Mississippi, Tennessee, and Alabama. Our inspector can determine the problem and recommend the appropriate underpinning solution.

Publish Date:

Last Modified Date:

AFS Coverage Map


Birmingham, AL

130 Interstate Commerce Crt. Bldg. 100 & 200
Alabaster, AL 35007

Chattanooga, TN

214 Industrial Park Dr.
Soddy-Daisy, TN 37379

Columbus, GA

2701 Opelika Road
Phenix City, AL 36870

Huntsville, AL

2415 Jordan Road
Huntsville, AL 35811

Knoxville, TN

3028 E Governor John Sevier Highway
Knoxville, TN 37914

Mobile, AL / Biloxi, MS

3131 Hamilton Blvd.
Theodore, AL 36582

Montgomery, AL

445 Dexter Avenue, Suite 4050
Montgomery, AL 36104

Nashville, TN

1519 Heil Quaker Blvd.
LaVergne, TN 37086