The 6 Statutory Ground Hazards Audited by Conveyancers
When solicitors instruct a Law Society CON29 or Groundsure Ground Stability report, six separate geohazards are evaluated:
1. Shrink-Swell Clay: Volume reduction in droughts (South East England).
2. Soluble Rocks (Sinkholes): Water dissolving underground chalk or limestone voids, causing sudden surface collapse (Kent, Ripon, Peak District).
3. Slope Instability & Landslides: Gravity-driven slippage on steep gradients (Cotswolds, South Wales Valleys, Jurassic Coast).
4. Running Sands: Loose sands saturated with groundwater losing bearing capacity under load.
5. Compressible Deposits: Soft peat and alluvial silt compressing under structural weight (Fens, Somerset Levels).
6. Past Mining Subsidence: Underground coal, limestone, or tin workings collapsing upwards towards the surface.
| Geological Hazard | High Risk Regions in UK | Typical Cause | Warning Signs on Property |
|---|---|---|---|
| Shrink-Swell Clay | Greater London, Essex, Beds, Oxon | Cohesive clay dehydration | Diagonal stepped masonry cracks |
| Chalk / Gypsum Sinkholes | Kent (Dartford), Ripon, Dorset | Subterranean dissolution voids | Sudden circular depressions in lawn |
| Slope Landslides | South Wales, Bath, Isle of Wight | Water lubrication on shear planes | Retaining wall bulges / tilted trees |
| Mining Subsidence | Yorkshire, Durham, Midlands, Wales | Unrecorded shallow bell-pits | Crown holes / structural sagging |
| Compressible Peat | The Fens, Somerset Levels, Mersey | Organic subsoil consolidation | Uneven sloping floors across rooms |