Foundation Appraisal

A foundation appraisal is typically required where there is a need to define a safe, compliant, and buildable foundation solution based on site-specific ground conditions.

This may be necessary at various stages of a project, particularly where design certainty is required to support planning, building control, or construction.

Foundation appraisals are commonly required in the following situations:

• Planning applications where foundation design needs to be defined or conditioned
• Building control submissions and warranty provider approvals (e.g. NHBC, LABC)
• Sites with variable ground conditions, made ground, or uncertain geotechnical properties
• Developments near trees where shrinkable clay may influence foundation design
• Basement or below-ground construction where ground and groundwater conditions are critical

By undertaking a foundation appraisal at the appropriate stage, you can ensure that foundation design is based on reliable data, reducing risk, avoiding costly redesign, and supporting a smooth transition from planning through to construction.

A ground investigation is the physical process of drilling, excavating, sampling, and testing the soil and rock beneath a site.  

A foundation appraisal is the subsequent analysis and interpretation of that data to determine what type of foundations are appropriate, what the design parameters are, and whether any geotechnical hazards need to be addressed. We typically provide both as a combined service. 

It depends on the scale of the extension and the ground conditions. For simple extensions on straightforward ground, building control may be satisfied with a standard foundation design.  

However, if there are trees nearby, clay soils anticipated, sloping ground, or known subsidence issues, a foundation appraisal will help ensure the foundations are correctly designed and avoid problems during construction or afterwards. 

Yes. We can undertake foundation assessments for existing properties where there are concerns about subsidence, settlement, or structural cracking.  

This may involve trial pit excavation to expose and inspect the existing foundations, combined with soil testing to determine whether ground movement is likely to continue. Our reports provide recommendations on whether remedial measures such as underpinning may be required. 

Our foundation appraisal reports are prepared in accordance with BS EN 1997 (Eurocode 7) and the associated UK National Annex, as well as relevant British Standards including BS 5930 (Code of Practice for Ground Investigations) and BS 8004 (Code of Practice for Foundations), where possible and subject to site-specific factors and constraints on investigation and testing methods. 

In practice, the extent to which a full Eurocode-compliant approach can be applied depends on the nature and scale of the investigation and the quality of the data that can reasonably be obtained. Constraints may include restricted site access (for example at occupied residential properties or operational sites), limitations on the depth or method of investigation due to below-ground obstructions or services, the recovery of disturbed rather than undisturbed samples in certain ground conditions, or cases where only limited in situ testing data is available. Where a prescribed pile is proposed and only windowless sample boreholes or trial pits are feasible, for example, the range of geotechnical parameters that can be reliably derived may be more limited than where cable percussive boreholes with Standard Penetration Testing are achievable. In such circumstances, our reports clearly set out the limitations of the available data, identify any assumptions made, and recommend further investigation where this is considered necessary to support the detailed foundation design. 

Where relevant, we also reference NHBC Standards Chapter 4.2 for building near trees on shrinkable clay soils, which sets out the minimum foundation depth requirements based on tree species, mature height, and the plasticity of the clay subsoil. For sites where infiltration-based drainage is proposed, our appraisals are informed by soakage testing to BRE Digest 365 and seasonal groundwater monitoring data, ensuring that the foundation and drainage design are considered together. Chemical aggressivity of the soil and groundwater is assessed in accordance with BRE Special Digest 1 and BS 8500 to inform the appropriate concrete specification, including Design Sulphate Class and Aggressive Chemical Environment for Concrete (ACEC) classification.