What You Need to Know About Underpinning a House

A house is one of the most important investments today, as not only does it give you a place to live but it also gives you security and financial freedom. A problem may arise when your home has developed floors that have become sloped over the years, or worse yet – your home may be close to collapsing! If this happens, then you need to go ahead and get underpinning done.

What Is Underpinning?

Underpinning is the procedure of supporting a weak structure by using steel poles or concrete to hold up any part of it that has sunk, and fixing the problem permanently so that you do not have to worry about anything else in the future. During this process, the foundations of the building will be dug up, and steel columns or concrete will be installed to support any side that appears to have a problem.

In most cases, underpinning is done when a house has sunken below its initial level. This can happen because the ground underneath is soft sand, clay, gravel, or even thick limestone rock. Whatever the reason, underpinning is the best way of bringing your home back to its original position.

Why Underpin your Home?

A lot of pressure builds up on the foundation of a house. This can put it under strain over time, causing any part of the floor to crack and thus leading to problems down the road. As such, it is important to get the whole foundation reinforced when you start hearing strange noises from your floors or when it shows visible signs of sinking. You can also check out house restumping for more great options.

The Different Types of Structural Support


Steel Columns

The steel columns are also called the hydraulic jack method, and they can be used for either a new house or an old one. A hole is dug up in the foundation, and then a steel pole with a hydraulic jack on top of it will be placed into that hole. The rest of the pole will be in the ground and will support all load from your floor to the foundation.

Concrete Columns

The second type of column that you can use is concrete, which comes in two different forms: one made entirely out of concrete (more expensive but ensures better performance) and others partially reinforced with steel or even another material. The partially reinforced ones will be cheaper, but they will not last a long time.


You can also use steel beams to reinforce your foundation. The beams will sit on top of the foundation, take any load from your house onto it completely, and then transfer that load into the foundation. These beams are used in places where you cannot use columns for some reason or when your house is large and the floor has sunk on one side in a way that columns can not handle.

When is Underpinning Needed?

Since the original foundation is not enough to support the structure, most homeowners must underpin their homes. This usually happens because the soil supporting the foundation has changed, such as through subsidence, moisture-induced expansion or contraction, nearby large trees, damaged plumbing that has not been repaired, or because the properties of the soil were not sufficiently understood when the foundation was first designed, meaning the foundation is inadequate for the circumstances.

Underpinning is also needed in less frequent situations for the following reasons:

  • The structure’s usage has changed, for example, as a result of a significant refurbishment.
  • Excavation of earth supporting existing foundations caused by adjoining new building to strengthen the strength of the building’s current foundations so they can hold an additional level.
  • Natural catastrophes that have caused the structure to move or become unstable, such as earthquakes, floods, or droughts.

Types of Underpinning?

Restumping or reblocking are two terms used to describe the process of fixing the stumped foundations of buildings. In essence, this entails changing out the foundation stumps as they develop cracks or other damages. This is not regarded as underpinning. Three techniques are currently in use that fall under this definition of underpinning: concrete slab, screw pile, and grout or resin injection.

Concrete Slab

The size of foundations was traditionally increased and strengthened through the use of concrete underpinning. This technique is still widely used today.

Screw Pile

This technique closes gaps and cracks by lifting the building back to its original place and securing it with steel piers and concrete footings. This technique is employed since using piers is seen to be a permanent fix that won’t be impacted by future changes in the ground surrounding the property.

Grout or resin injection

Although it is not really underpinning, this is the newest approach that is now available. Injecting glue or grout into the ground causes it to expand and compress the ground by filling up any gaps under the slab. In terms of the end cost and the durability of the repair, it is the least quantifiable option and is not appropriate for all types of ground conditions.

What to Ask a Repair Company Before Hiring Them?

Before you hire any underpinning company, it is important to find out if they have enough experience. They should show you references for the jobs that they have done before. They should also tell you how much their services cost.

When choosing a company, make sure that their equipment is of quality, and that they use high-quality materials. You should also find out how long the job will take. If you have to pay them by the hour, that is fine, but don’t base your decision solely on the cost factor. You should hire somebody that will do a good job for you.

Can You Do Underpinning Yourself?

If you are not in any rush to get this done and have the knowledge required to do the job, you can do it yourself. There are plenty of tutorials available online about how to go about this process.

How Much Does Underpinning Cost?

The cost of underpinning is going to differ according to company, location, and type of property. The average cost will be around $4000 or even less for a simple job with just one room, but you should expect the price to rise if it gets more complicated than that.

Underpinning is the best way to bring your foundation back to its original position. Though it can be quite expensive, it will prolong the life of your home by many years and can save you from having repairs down the road. You should not wait for more damage to occur before you get this done.