Difference Between Underpinning and Resin Injection

In the construction industry, fixing foundation problems is key to keeping any building safe and stable. Two common methods for tackling foundation subsidence are underpinning and resin injection. Both are designed to strengthen and stabilise foundations, but they use different techniques, materials, and are suited to different situations. Knowing the difference between the two will help you choose the right solution for your project.

What is Underpinning?

Underpinning is a traditional method used to stabilise and strengthen the foundation of a building that has shifted or subsided. It works by extending the foundation to a deeper level or adding new support underneath the existing foundation.

How Does Underpinning Work?

Underpinning involves digging beneath the current foundation and adding extra support, often in the form of concrete. This increases the foundation’s load-bearing capacity by shifting the building’s weight to deeper, more stable soil or rock.

When is Underpinning Needed?

Underpinning is typically required when:

  • The current foundation has weakened or failed.
  • The building’s use has changed, causing heavier loads than the foundation was designed to handle.
  • Shifting soil conditions have caused the foundation to crack or move.

Types of Underpinning

There are different ways to underpin a foundation:

  • Mass Concrete Underpinning: A traditional method where sections of the foundation are dug out and replaced with concrete to add strength.
  • Beam and Base Underpinning: Involves constructing concrete beams beneath the foundation and connecting them to load-bearing soil for added support.
  • Mini-piled Underpinning: Small piles are drilled deep into the ground to reach stable soil, ideal for sites with limited access or where deep foundations are required.

What is Resin Injection?

Resin injection is a modern alternative to underpinning. It involves injecting a specialised resin into the ground beneath the foundation to fill gaps and stabilise the soil. As the resin expands and hardens, it strengthens the ground, increasing its load-bearing capacity.

How Does Resin Injection Work?

Resin injection involves drilling small holes into the ground and injecting resin under pressure. The resin spreads out, fills voids, and solidifies, creating a stable base. It’s a faster process than underpinning and causes less disruption.

When is Resin Injection Used?

Resin injection is ideal for:

  • Fixing minor subsidence or foundation issues.
  • Projects that need to be completed quickly, as it causes minimal disruption.
  • Sites with limited access, where traditional underpinning may not be possible.

Benefits of Resin Injection

Resin injection has several advantages over traditional underpinning:

  • Speed: The process can often be completed in just a few days.
  • Minimal Disruption: Only small holes need to be drilled, making it far less invasive than underpinning.
  • Precision: The resin can be injected precisely where it’s needed, making it perfect for targeted repairs.

Underpinning vs. Resin Injection: Key Differences

Let’s compare the two methods based on key factors:

  1. Method
    • Underpinning: Involves digging beneath the foundation and adding extra support, often using concrete.
    • Resin Injection: Involves injecting resin into the soil, which expands and stabilises the ground.
  2. Time and Disruption
    • Underpinning: Generally takes longer and is more disruptive, involving excavation and heavy machinery.
    • Resin Injection: Quicker and less invasive, with minimal disturbance to the building and its surroundings.
  3. Materials
    • Underpinning: Uses concrete or similar materials to reinforce the foundation.
    • Resin Injection: Uses a specialised resin that expands to fill voids and stabilise the soil.
  4. Applications
    • Underpinning: Best for buildings with major foundation issues or where significant structural support is needed.
    • Resin Injection: Suited to smaller subsidence problems or when quick, localised repairs are required.

 

Both underpinning and resin injection can effectively address foundation problems, but they’re suited to different situations. Underpinning is ideal for larger structural support, while resin injection offers a faster, more targeted solution for minor issues.

Choosing Vision Specialist Contracting for concrete restoration means working with a company that combines decades of experience with cutting-edge techniques. Our team understands that foundation issues can be stressful, which is why we offer tailored solutions designed to get your building back to full stability with minimal disruption. 

With over 50 years in the construction and refurbishment industry, we don’t just fix problems—we create lasting solutions. Our customer-first approach means we assess your unique situation, guide you through the process, and ensure the most efficient and effective method is used. At Vision SC, your building’s stability is our top priority, and we’re here to help you protect your property for the long term.