Geotech Surveys

Before a foundation is designed or a structure built, you need to understand the ground you’re building on. Geotechnical surveys assess soil, rock and subsurface conditions to inform foundation design, site suitability and construction planning, reducing the risk of unexpected ground conditions once work is underway, whether that’s a single building extension or a large-scale development.

A full geotechnical investigation often includes physical ground investigation, such as boreholes and laboratory soil testing, to establish soil composition, bearing capacity and groundwater conditions in detail. Subvision Surveys’ role sits alongside this, using non-destructive GPR-based assessment to identify subsurface features, voids, existing foundations and buried obstructions across a site before physical investigation begins. Rather than drilling boreholes speculatively across a site and hoping to encounter anything unusual, a GPR survey first builds a picture of where ground conditions vary, helping direct where more detailed, physical investigation is actually needed.

GPR responds differently depending on what it passes through, which allows our surveyors to identify a range of subsurface conditions relevant to construction planning. This includes existing or historic foundations from previous structures on a site, buried made ground or backfill that may behave differently to natural strata under load, voids or areas of loose or disturbed ground, and the depth to bedrock or a significant change in ground material where this is detectable. On sites with a history of previous development, this can be particularly valuable, revealing old foundations, basements or services that may not appear on any existing record.

The type of ground being surveyed has a real effect on what GPR can detect and how deep it can see. Dry, sandy or gravelly soils generally allow radar signals to penetrate further, giving clearer results at depth. Wet or clay-heavy soils, common across much of the South East, conduct electrical signals more readily, which can limit penetration depth and make deeper features harder to resolve. Our surveyors take this into account when planning a survey and interpreting results, adjusting equipment settings and expectations to suit the ground conditions of your specific site, rather than applying a one-size-fits-all approach regardless of soil type.

Geotech-related GPR surveys are often carried out alongside our Borehole Excavation Clearance, Virtual Trial Holes and Desktop Utility Search Packs services, giving developers and engineers a fuller site picture before construction or consolidation work begins, without needing to coordinate between multiple separate providers for each stage of investigation.

Subvision Surveys is SSIP and ISO accredited, with a team of over 25 surveying professionals delivering GPR-based geotechnical surveys for developers, engineers and contractors across London, the South East and nationwide.

Contact Subvision Surveys today to discuss your geotech survey requirements, or speak to one of our experts on 0333 920 9427.