How Resin Injection Works: The Modern Fix for Subsidence

What Is Geopolymer Resin Injection?

Geopolymer resin injection works by pumping a specially engineered two-part resin into the ground beneath your foundations. When the two components mix underground, the resin expands — typically to 4 times its original volume. As it expands, it fills voids, compacts loose soil, and hardens to create a stable, load-bearing platform. The entire process is controlled and monitored in real time.

How Does It Compare to Traditional Underpinning?

Resin injection and traditional underpinning solve the same problem but in very different ways. Here's how they compare:

The Injection Process: Step by Step

Understanding the process helps you know what to expect on the day. Here's exactly what happens:

1. Pre-Treatment Survey

We map the affected area using level surveys and ground-penetrating radar to plan exactly where and how much resin is needed. This planning phase is crucial — it ensures we treat the right areas and use the right volume of material.

2. Drilling Access Points

Small holes (just 16mm diameter — about the width of your little finger) are drilled through the floor slab or externally at strategic points. These are far less invasive than the trenches required for traditional underpinning.

3. Controlled Injection

The two-part resin is injected under controlled pressure through the access points. It flows into voids and weak zones, expands, and begins to cure immediately. Our engineers monitor building levels in real time using laser equipment — this allows precision control, often to within 1mm accuracy.

4. Making Good

The small drill holes are sealed and patched. There's minimal cosmetic repair needed, and most homeowners can't tell where the work was done within a few weeks.

When Is Resin Injection the Right Choice?

Resin injection is ideal for many — but not all — subsidence situations. It works best when the ground needs compaction or void filling, and the structural damage is moderate.

• Ground settlement caused by clay shrinkage or washout
• Small to medium underground voids
• Slab re-levelling for sunken floors and driveways
• Properties where minimal disruption is essential
• Situations where speed matters — such as pending property sales

Is the Repair Permanent?

Yes. The cured geopolymer resin is completely inert — it doesn't degrade, dissolve, or lose strength over time. It's a permanent addition to the ground beneath your property. However, it's worth noting that if the original cause of subsidence isn't addressed (for example, a leaking drain or a large tree extracting moisture from clay soil), new movement could occur nearby. That's why our survey always identifies the root cause, not just the symptoms.