What is Foundation Underpinning?

Foundation pier attached to a home's concrete footing.

Imagine waking up one morning to find cracks in your walls and a sinking feeling—literally—beneath your feet. These are telltale signs of foundation problems, a homeowner’s nightmare. However, there’s a solution: foundation underpinning.

This repair technique reinforces the foundation and stabilizes your home, making it safer and more secure. Let’s learn more about how it works.

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Foundation Underpinning Explained

Foundation underpinning is a process used to strengthen and stabilize the foundation of an existing building. It becomes necessary when the original foundation is not strong or stable enough due to various reasons, such as changes in soil conditions, poor initial construction, or the need to support additional floors. With underpinning, you increase the structural stability of the foundation and provide the best possible support to your building.

Types of Underpinning Methods

Several methods of underpinning are available, each suited to different foundation issues and soil conditions. Understanding the differences allows you to pick the best one for your home.

Traditional Underpinning

Traditional underpinning, also known as “mass concrete underpinning”, is one of the oldest methods. It involves excavating sections below the foundation and pouring concrete to extend the foundation’s depth. While this method is reliable, it is labor-intensive and time-consuming.

Beam and Base Underpinning

The beam and base method involves constructing a reinforced concrete beam below the foundation, which transfers the building’s load to mass concrete bases. This method is effective for structures with weak soils or varying load requirements.

Mini-Piled Underpinning

Mini-piled underpinning is a modern technique that uses small-diameter piles to transfer the load to deeper, more stable soil layers. This method is ideal for sites with restricted access or where traditional underpinning is not feasible due to ground conditions.

Foundation Piers

Foundation piers are components used to stabilize and support foundations in various soil conditions. These piers are essential for addressing foundation settlement and ensuring long-term structural integrity.

Helical Piers: Screw-like steel shafts twist into the ground to provide support; quick to install and suitable for various soil conditions.
Push Piers: Hydraulically driven steel piers push into the ground until they reach stable soil or bedrock, offering a permanent solution to foundation settlement issues.
Slab Piers: Specifically designed for slab foundations, these piers are installed directly beneath the concrete slab to lift and stabilize it.

How Underpinning Works

Understanding the underpinning process helps homeowners appreciate the complexity and precision of stabilizing a foundation. Here is a step-by-step overview of how it is typically carried out:

Initial Assessment

Foundation expert inspecting a home with laser level.

The first step in the underpinning process is a thorough inspection of the building and soil conditions. A professional engineer or foundation specialist will assess the extent of the damage and determine the best underpinning method.

Soil Testing

Soil testing is crucial to understanding the underlying issues causing foundation problems. Tests will reveal soil composition, moisture levels, and other factors that affect the foundation’s stability.

Planning

Experts can develop the most appropriate repair plan based on the assessment and soil test results. This plan outlines the chosen method, required materials, and the step-by-step process.

Excavation and Installation

Excavator being used to prepare for underpinning.

The actual underpinning work begins with excavation and the placement of new supports according to the chosen method. This phase requires precision and expertise to ensure the stability of the building during and after the process.

Monitoring

Post-implementation monitoring is essential to ensure the chosen method is effective. Regular inspections and maintenance checks help in identifying any further issues and taking corrective actions promptly.

Benefits of Foundation Underpinning

Structural Stability: Enhances the structural stability of a building, ensuring it can withstand various stresses and remain safe.
Property Value: Increases the property’s resale value, making it more attractive to potential buyers.
Safety: Directly impacts the safety of occupants by rectifying potential hazards associated with foundation issues.
Longevity: Extends the life of a building by addressing foundational problems before they escalate, preventing costly future repairs.

Expert Foundation Underpinning With AFS

AFS crewman installing slab pier in a home.

Foundation underpinning protects the structural integrity of a building. Whether dealing with shifting soils, poor construction, or a need for additional support, underpinning is a reliable solution.

At AFS, we use foundation piers to provide industry-leading foundation underpinnings. If your home needs foundation repair, contact us today to schedule a free inspection. Your home’s stability is our top priority.

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Related Resources

A Guide to Foundation Repair for Different Foundation Types

When foundation damage occurs, it puts your entire home at risk. In this guide, we'll outline the various ways to repair a foundation and why doing so is a valuable investment in the long-term.

How to Install Helical Piers in 5 Steps

Helical piers are a way to permanently stabilize settling foundations. Learn how AFS installs them in our step-by-step guide.

What is Backfill in Construction? A Guide to Types and Uses

Backfill provides support and drainage for foundations, retaining walls, and more.

Ted Dryce

Content Writer

Ted is an SEO Content Writer who has been with Groundworks since 2021. He’s covered home repair topics ranging from crawl space encapsulation to regional soil conditions. When he’s not working, Ted is performing improv comedy and working on his own creative projects.