What is Underpinning?

Helical pier underpinning stabilizing home's foundation

A home’s foundation changes over time. Whether it’s a few months after construction or several years later, these changes can reduce the foundation’s load-bearing capacity, with weak or shifting soils being the primary cause.

As a result, the foundation may crack or settle unevenly, jeopardizing your safety and your home’s structural integrity. Fortunately, there is a solution: foundation underpinning.

This page explores the underpinning process and foundation repair options.

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Underpinning: What is it?

Underpinning is a foundation repair method that strengthens the foundation of a home or a building by distributing the structure’s load above a wider area. The technique involves installing new, robust structural supports beneath the existing foundation, like concrete footings or steel piers. It’s a complex and disruptive process best handled by foundation repair experts.

Is Underpinning Necessary?

illustraion of foundation settlement and cracking that requires underpinning

Underpinning is necessary for severely damaged, sinking, or settling foundations or when additional weight support is required. Poor construction, soil erosion, earthquakes, flooding, or adding excessive weight can cause wall cracks, uneven floors, and other structural problems requiring foundation underpinning methods.

If you are unsure whether repair is necessary for your home, contact a professional to inspect your foundation and determine whether underpinning is needed.

Types of Foundation Underpinning

Foundation underpinning involves various methods. The method used on a foundation depends on the damage, foundation depth, soil type, and other factors. Below, we discuss foundation piers, a trusted underpinning method many homeowners and commercial property owners choose.

Foundation Piers

Foundation piers strengthen, stabilize, and lift damaged foundations by transferring the load to more stable bedrock or soil. The pier type used varies depending on the soil conditions, the extent of damage, and other site-specific factors. Here are the three pier underpinning types:

illustration of helical pier underpinning driven into soil underneath a house

Helical Pier: Uses screw-like bladed piers driven deep into the soil, transferring weight from weak soil to more stable ground or bedrock. They stabilize and lift the foundation.
Push Pier: Hydraulic jacks press these piers into the ground. They are used for shallow foundations or when there is limited foundation access. Push piers stabilize and support foundations.
Slab Pier: These piers are designed explicitly for slab foundations. They redistribute the structure’s weight to firmer, more stable soil layers, preventing further settling and safeguarding against soil changes and shifts.

Pier underpinning is an intricate process requiring professional expertise. After installation, experts benchmark the area for future monitoring.

What is Benchmarking?

Foundation benchmarking is a process implemented after pier installation. Technicians document each pier’s location, depth, and hydraulic resistance encountered during installation. This data is kept as a reference throughout the lifespan of your house or building. If future foundation repairs are needed, this benchmarking information will be used to help the technician assess the current condition of your foundation.

How to Benchmark a Foundation

Foundation benchmarking includes several intricate steps:

Pier underpinning installation in basement.

Each pier undergoes load testing to determine the correct depth and spacing, with readings taken for future reference.
The installer marks each pier with a benchmark guide.
A laser level is used to mark small rivets on the foundation; each used as a reference point for future foundation inspections and monitoring.

Benchmarking offers homeowners peace of mind by providing a reference guide for foundation stability and movement. This process requires technical expertise and the skills of a professional. Experts use precise measurements to monitor foundation movement, document the initial pier positions, and compare them during future inspections.

How is Future Foundation Movement Measured?

Comparison surveys are used to check for foundation movement. Structural engineers follow guidelines established by the American Society of Civil Engineers (ASCE). These standardized procedures evaluate localized foundation deflection, tilt, and total foundation deflection. This essential data compares foundation elevation and tolerance levels before and after movement. Regular comparative inspections are necessary to assess your foundation’s current state, confirming no elevation issues or discrepancies.

Following local building codes and other standards may also be required depending on your region or the project. Monitoring crack growth and using inclinometer tools to measure tilt may also be used to provide valuable data on foundation stability.

Contact a foundation repair expert for a free inspection if you suspect settlement or sinking.

Trusted Underpinning Solutions: Foundation Recovery Systems

Foundation underpinning is essential to keep your home safe and stable long term, so choosing a reliable company is crucial. The highly-trained experts at Foundation Recovery Systems offer free inspections to determine if you have foundation damage and how to address it. We answer your questions so you feel confident in your decision.

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Foundation Underpinning FAQs

Should I Install Foundation Piers Myself?

We strongly advise against DIY installation. Incorrect placement can lead to severe complications.

Can foundation piers be used in commercial buildings?

Yes, foundation piers are commonly used in both residential and commercial structures.

How long does the installation of push piers take?

The duration is contingent on several factors, including the scope of the issue, installation site, and number of piers needed. A free consultation with a Foundation Repair Systems expert will provide a precise timetable.

Leah Leitow

Content Writer

Leah is a Content Writer for Groundworks with nearly ten years of experience working in the foundation repair industry. Her experience ranges from working with homeowners to find the right solution to training inspectors and staff. In her background as a Michigan journalist, she gained invaluable insight into people's lives throughout our state. Leah lives in metro Detroit with her husband and two sons.

Related Resources

Expert Guide: 5 Best Foundation Repair Types

Learn about common causes of foundation damage and get expert solutions to ensure your home's safety.

What Is Foundation Settlement?

Foundation settlement puts your home at risk of structural damage. Learn everything you need to know about it to protect your home from its effects.

FRS crew member measuring wall braces on basement wall

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