Clay Shrinkage Ground Improvement – Hockley, Essex
Background
The property is a 1920s solid brick wall home located in Hockley, Essex. Like many homes built on clay soils, it has experienced long-term seasonal movement, with historical issues dating back to the 1970s when clay heave required internal floor supports to be rebuilt.
Around 25 years ago, an insurance claim was made following significant cracking at the rear of the property. The response at that time was limited to superficial repairs—re-rendering and replastering affected areas. Despite this, seasonal movement persisted, particularly impacting interior doors and finishes.
With insurance cover no longer in place, the homeowner sought a long-term solution to improve ground stability and reduce the ongoing impact of clay shrinkage on the building’s structure.
Challenges
The property sits on shrink-swell clay and is in close proximity to a large mature oak tree—well known to exacerbate desiccation in soils. Previous site history, including past clay heave and a complex layout of internal utilities, added to the challenge.
Given the presence of buried services and structural idiosyncrasies, any solution had to be carefully planned and executed with minimal risk to existing infrastructure.
Alternative Solutions
The traditional approach to addressing this issue would have been mass concrete underpinning. However, this method would involve extensive excavation, significant disruption to the property, and a long construction period.
It would also require the removal or bypassing of buried services and potentially cause new structural stress points within the building. Due to the depth required (2.8m into the clay, as established by site testing), traditional underpinning would have entailed high costs, prolonged work on-site, and increased carbon emissions due to the volume of concrete and excavation required.
Why Geobear
Geobear proposed a ground improvement solution using its engineered geopolymer injection method. The treatment plan involved injecting resin beneath the foundations to a depth of 1.5m below foundation level at 0.5m centres over an 18-metre linear treatment zone, including both external and internal supporting walls.
The work was completed in just two and a half days, with minimal disruption. The client noted:
Time / Cost Saving Compared to Traditional Underpinning
A traditional underpinning scheme for a property of this type could take 3–6 weeks to complete, not including reinstatement of floors and finishes. With Geobear, the solution was delivered in days, saving a vast amount of time and disruption to the homeowner.
Time on site with Geobear: 2.5 days vs. 15–30 working days for traditional underpinning.
Carbon Saving
According to Geobear’s independent carbon assessment by Carbon Footprint Ltd, a comparable residential project using traditional piled raft underpinning would produce approximately 5.81 tonnes CO₂e. In contrast, Geobear’s geopolymer solution generates just 2.73 tonnes CO₂e.
Given the near-identical treatment scope in Hockley (18 linear metres at 1.5m depth), this project delivered a carbon saving of:
- Carbon reduction: Approx. 3.08 tonnes CO₂e saved
- Reduction: 53% lower emissions vs. traditional underpinning
These savings were achieved by avoiding excavation, reducing material use (particularly concrete and steel), and shortening time on site.
Source: Carbon Footprint Ltd – Life Cycle Assessment Report for Geobear, v2.0
For further information on Geobear’s carbon savings,
view our Carbon Footprint Reports.
