Property Subsidence
Challenge
Subsidence caused by a mature oak tree threatened structural stability, with tree removal planned as the default solution.
Solution
Geobear stabilised the property using targeted geopolymer injection, eliminating the need for tree removal or underpinning.
Complete stabilisation programme
No disruption to foundations or surroundings
Saved - structural repair without environmental impact
In November 2022, Geobear was appointed to stabilise a residential property in Bristol affected by subsidence linked to a nearby 22m oak tree. The case attracted significant public attention, with local campaigners actively opposing the planned removal of the tree—going as far as occupying it to prevent felling.
The subsidence claim was being managed through insurance channels, with the initial remediation strategy focused on tree removal followed by long-term monitoring. However, prior to felling, the loss adjuster identified Geobear’s geopolymer solution as a viable alternative.
Geobear designed and delivered a ground improvement solution that stabilised the property while allowing the tree to remain. The project gained national visibility and was featured by the BBC News.
The conventional approach would involve removing the tree and monitoring the property over 18–24 months before determining if structural repairs were still required. This would delay resolution and introduce uncertainty.
Underpinning would require full excavation around the affected foundations and placement of mass concrete. This process typically takes several months and would have required road closures due to site access constraints, causing significant disruption.
Geobear designed a targeted ground improvement solution based on site investigation data, incorporating both lateral and vertical soil treatment zones beneath the affected foundations.
Small diameter injection tubes were installed through the foundation to precise depths, allowing geopolymer resin to be injected directly into the desiccated clay soils.
The expanding geopolymer:
The treatment was carefully monitored in real time using precision laser levels to ensure controlled ground response.
All works were completed within three days, with no need for excavation or structural alterations.
Traditional underpinning solutions rely on extensive excavation and the installation of mass concrete beneath existing foundations. This process is carbon intensive due to:
In contrast, the Geobear solution:
Based on comparable foundation stabilisation works, geopolymer injection can achieve carbon savings of up to 60–70% compared to traditional underpinning methods.
In this project, the ability to retain the mature oak tree also delivered an additional environmental benefit by preserving an established carbon sink and supporting local biodiversity.
The project received national coverage via BBC News, highlighting the innovative approach to resolving subsidence without tree removal.
Marvin Rees commented:
“This is a really good piece of news — we’ve found a way to protect the home without felling the tree. Trees make up the lungs of Bristol; they support our city’s ecology. We need to protect our biodiversity and deliver solutions in a sustainable, decarbonised way.”
Every home is unique. Our experts are ready to listen and provide answers tailored to your specific property and concerns.
