What Is Resin Injection Ground Stabilisation?
Resin injection ground stabilisation has revolutionised the treatment of subsidence over the past two decades. Once, the only option for a property experiencing foundation movement was traditional underpinning — a process involving extensive excavation, weeks of disruption, and significant cost. Today, resin injection offers a faster, less invasive, and often more cost-effective alternative.
For homeowners across Cornwall dealing with subsidence, understanding resin injection technology can help you make informed decisions about your property's treatment. This guide explains how the process works, when it's appropriate, and what you can expect.
How Resin Injection Works
The Technology
Resin injection uses expanding geopolymer resins — highly engineered chemical compounds that are injected as a liquid and expand to many times their original volume within the ground. As the resin expands, it fills voids, compacts loose soil, and can even lift structures that have settled.
The resins used are inert once cured, meaning they don't break down over time, aren't affected by groundwater, and won't leach chemicals into the surrounding soil. They're environmentally certified and have been used in major civil engineering projects worldwide.
The Process
The resin injection process follows a carefully controlled sequence. Small injection tubes (typically 12-16mm diameter) are drilled through the floor slab or foundation at predetermined points. The injection pattern is designed based on site investigation data to target the specific areas of ground weakness.
Resin is then pumped through these tubes into the ground beneath the foundations. The injection is monitored in real-time using precision laser levels that detect movement as small as 0.5mm. This allows the operative to control exactly how much resin is injected at each point, ensuring the ground is stabilised without over-lifting the structure.
Real-Time Monitoring
One of the key advantages of resin injection over traditional methods is the level of control possible during the treatment. Laser monitoring systems track the building's response to the injection in real-time, allowing the operative to adjust injection rates and volumes precisely.
This monitoring continues throughout the treatment and for a period afterwards to confirm that the ground has stabilised. The data is recorded and forms part of the completion documentation.
When Is Resin Injection the Right Solution?
Resin injection is particularly effective in the following situations found commonly across Cornwall:
Mining Voids
Cornwall's extensive mining heritage has left countless voids beneath properties. Resin injection is ideal for filling these voids, whether they're caused by collapsed mine workings, deteriorating mine shafts, or the natural erosion of material around abandoned tunnels. Our resin injection service has treated numerous properties affected by mining subsidence in areas like Camborne, Redruth, and St Austell.
Soft or Loose Ground
Where ground has become soft due to water ingress, washout, or poor compaction, resin injection can compact and stabilise it. The expanding resin displaces water, compresses loose material, and creates a solid bearing platform.
Shallow Subsidence
For properties experiencing subsidence where the cause is within the top few metres of ground, resin injection is often the most practical and cost-effective solution. It's particularly effective where drainage CCTV surveys have identified leaking drains that have washed out ground beneath foundations.
Resin Injection vs Traditional Underpinning
Understanding the differences helps you appreciate when each method is appropriate:
Speed
Resin injection typically takes 1-2 days for a residential property, compared to 3-6 weeks for traditional underpinning.
Disruption
Resin injection requires only small drill holes through the floor slab — no excavation, no removal of soil, and no concrete curing time. You can usually remain in your home throughout.
Cost
Resin injection typically costs 50-70% less than traditional underpinning for comparable subsidence issues.
Limitations
Resin injection isn't suitable for every situation. Where foundations need to be deepened significantly, where the ground requires structural piles to reach competent strata, or where the movement is too severe, traditional underpinning or helical piling may be more appropriate.
What Happens After Treatment?
After resin injection treatment, your property is monitored for a period to confirm stabilisation. Once confirmed, structural masonry repairs such as crack stitching can be carried out to repair the damage caused by the original movement.
The treatment comes with comprehensive documentation including injection records, monitoring data, and a completion certificate. This documentation is important for insurance purposes and for future property transactions.
Costs in Cornwall
Resin injection costs depend on the area to be treated and the volume of resin required. For most residential properties in Cornwall, treatment costs range from £3,000 to £12,000. This compares favourably with underpinning costs of £10,000-£50,000 and helical piling costs of £8,000-£30,000.
Your buildings insurance may cover the cost if the subsidence is caused by an insured peril. Our insurance claim management service can help you navigate the claims process.