The Step-by-Step Guide to Underpinning

This step-by-step guide on underpinning will help you determine if you need underpinning for your home and what steps to take.

To stabilize an existing home and to prevent movement, it is necessary to build new footings that are deeper.

The building can be supported by extra footings of concrete or screwed-in steel piers.

This step-by-step guide on underpinning can help you find the solution to cracks.

Hope it helps.

Cracks on Your House

Cracks can cause a lot of anxiety.

This is something I constantly hear. My house’s structural integrity may have been compromised by the movement of concrete footings or slabs. What should I talk to? A structural engineer, or someone who specialises in slab stabilisation or underpinning?

What a scary thing, right?

Our homes are filled with so much affection. We put so much love into our homes. We want to be loved by our houses, to feel safe and protected. When our homes move or crack, we try to stabilize the movement as soon as possible. We are structural engineers who have been trusted to fix many houses. Here is a list of tools we use to fix and stabilize your house. The biggest tool in our toolbox is underpinning. It’s the game changer. The game-changer. It is expensive, and if not done correctly can cause a lot of damage to your house. Underpinning could be your best option to repair your home, depending on the circumstances. It might be. Let’s start with the basics.

What Is Underpinning?

The process of underpinning is to strengthen the foundations by adding additional footings made from concrete or steel. This will stabilise, reinforce or raise the current footings. The process of underpinning involves adding extra footings to your home’s foundation. This will allow your house to be supported by soils that are more stable. Underpinning’s purpose is to secure your foundations in soil that will be more stable and stiffer. It is also stronger, less likely to shift, and is therefore less likely to cause future problems. Google states that “underpinning” is the solid foundation placed below ground to strengthen or support a building.

When does a house need to be underpinned?

The term “underpinning” is so popular right now when it comes to resolving movement issues with homes. Is underpinning the best solution for your house’s movement? Not all house footings are moving for the same reason, and therefore not every footing move requires underpinning. When is underpinning necessary? When the foundations of a building or set have subsided, or fallen for reasons that are unlikely to be reversed, underpinning can help. When a footing has been constructed on soft or loose soil, such as uncontrolled fill (which is prone to footing movement), it is not likely that the footing will move back. Underpin footings are a good option if your original house footings were not installed deeply enough. They can improve your home’s stability. You can use them to raise your house to almost level.

When is Underpinning Not Recommended?

Uneven changes in the soil moisture content (also called slab heave) can cause reversible footing movements. For slab heave, underpinnings are not recommended. The movement can be reversed. Underpinning is not the most effective way to fix reactive clay issues.

What is concrete underpinning?

In order to concrete underpin a home, you will need to dig new bored pier feet at a distance of 2m-3m around the exterior. At times, concrete underpins may also be required within the home. Underpin footings must be able to reach deep into soil that can support the structure’s weight. The deeper footings must then be connected to the building. This is often achieved by digging beneath the existing foundation (undermining it) in order to create a sturdy prop. Each pier-and-prop arrangement is then reinforced with reinforcement bars made of steel and filled with cement. Underpinning contractors who are clever leave space between their underpins and existing footings so that, once the concrete has cured and become strong enough to support the weight of the house again, they can use the underpins. The jacking process can sometimes close settlement cracks in the house. However, because cracks may dislodge unequally and not close every time.

Does underpinning only apply to outside footings?

No. Underpinning can also be done on the footings of a home in the middle. Underpinning contractors must dig under the house to reach the soil beneath. However, the work can be done as if it were the footing on the exterior of the home.

How long does underpinning take?

The length of the process depends on how many underpins the engineer specifies. The work for a home that needs up to 10 underpins will take about two weeks. You might have to leave your home for a few weeks if your entire house requires underpinning.

In 5 simple steps, you can get your home firmly anchored.

This is a guide on how to install underpinnings:

Step 1: Assessment by the structural engineer

A structural engineer is needed to evaluate your house. A structural engineer must be qualified to:

Experienced with assessing damage and repairs

Have local knowledge

Be registered in your locality and easy to talk to.

Do not assume that you will need to have underpinning installed before you arrange an inspection. Leave this assessment up to structural engineers. Describe the symptoms. When was the first crack visible? Your bedroom door sticks or doesn’t latch. The brickwork on the roof of the garage is cracked.

Some engineers don’t have the qualifications. Some engineers don’t have their own business. You’ll have to do a bit more work, but you’ll reduce the chance of you getting sucked into work you’re not really interested in. Do your homework and ensure that you trust the advice you receive from any engineer.

Step 2: Soil Test

Before your contractor can quote you for your underpinning project, he must first assess the soil conditions at your location. The soil tester is the answer. You need to test the soil depth. This will help you determine the depth of your underpinnings. The soil test for the underpinning is much deeper (6-8 m) and can also include recording moisture levels at 500mm intervals. You should use a soil testing company that is familiar with the local area, and who can bring a machine to the test area.

Step 3: Engineering Design

It is for this reason that you hired a structural engineering firm to evaluate your home. The engineer should complete the design of the underpinning by a professional structural engineer in your locality. A structural engineer uses the data from the soil report in order to decide the location, distance and depth for the underpins to be installed to stabilize your house. When the engineer first quoted for your project, he didn’t know that your home would need to be underpinned. So expect to have to pay to design your underpinnings. You may end up paying more than you need to for the design of your underpinnings if an underpinning company or resin injection firm offers to cover it.

The Fourth Step: Engagement of an Underpinning Contractor

Underpinning quotations should include what’s included and what’s excluded, as well as a general indication of the costs that could be different. A good contractor for underpinning will also include the costs of removing or replacing concrete slabs and getting plumbing checked once the job is done.

Ask for references and talk to people who used to use the contractor before if the prices are difficult to compare.

Did the worker make a mess but refuse to clean up after themselves?

Was their behavior polite and friendly?

Did they deliver on their promises?

Were there any price changes that were unexpected?

Build the Underpins

Now, the contractor who will be constructing the underpinnings is in charge of this project. If there are many underpins, they will build them in phases. The structural engineer will be present before each pour of concrete to make sure the footings for underpins are excavated at the right depth. The underpinning concrete will be placed and poured. They’ll return a few days later to stabilize and jack-up the home. The underpinning contractor is responsible for finalizing all paperwork and submitting a final bill. They will also give you the copy of final floor levels.