Groundworks and Foundations for New Build Developments: A Developer’s Guide
On almost every development, the cost and programme risk sits below ground. Before a brick is laid, the site has to be cleared, excavated, drained and supported by foundations that suit the soil. Get this stage right and the rest of the build flows. Get it wrong and the whole scheme can slip.
This guide explains the main elements of groundworks and how developers can keep them under control.
Start with ground investigation
A ground investigation tells you what is beneath the site: soil type, groundwater level, bearing capacity and any contamination. It should be completed before you fix the build budget, and ideally before you buy. Without it, foundation costs are guesswork.
Typical investigations include boreholes or trial pits, soil sampling and laboratory testing. A structural engineer then uses the findings to design foundations. Where trees are present, the engineer also considers root influence on shrinkable clay.
Common foundation types
Strip foundations: continuous concrete under load-bearing walls, suited to good ground
Trench-fill foundations: deeper strips filled with concrete, common on clay
Raft foundations: a reinforced slab that spreads loads over soft or variable ground
Pad foundations: individual bases under columns, used with framed buildings
Piled foundations: columns driven or bored into deeper strata where surface soils are poor
Drainage and services
Surface water and foul drainage need designing alongside the foundations. Where infiltration is poor, attenuation tanks or controlled discharge to a sewer may be required, and the local water company has to approve connections. Utilities, including gas, electric, water and telecoms, also need early applications because lead times can run to many weeks.
Typical risks to price in
Unexpected obstructions such as old foundations, buried tanks or services can appear once excavation begins. Contaminated soil must be tested, removed or treated, and water ingress in excavations needs pumping. Good contractors identify these risks at tender and allocate sensible provisional sums, rather than leaving them as surprises. See our guide to de-risking a development scheme for more on contingency planning.
Adjacent properties and party walls
Excavation near neighbouring buildings may trigger Party Wall obligations, particularly where foundations will be deeper than neighbours’. Notices must be served in good time, and surveys prepared. Our article on party wall agreements explains the process.
Frequently asked questions
How much does groundworks cost?
It depends on site conditions, foundation type, drainage and access. A ground investigation and engineer’s design are the first steps to a reliable figure.
Do I need a ground investigation?
For almost every new build, yes. It informs foundation design and exposes risks such as contamination or high groundwater.
What happens if the contractor hits something unexpected?
Contracts should state how unforeseen ground conditions are handled. Provisional sums and clear change control protect both parties.
Can Berati manage groundworks on my scheme?
Yes. We manage groundworks as part of our main contractor service on new builds and conversions.
Talk to Berati Construction
Preparing a site and want realistic groundworks advice? Berati Construction Ltd has more than 30 years' experience delivering new builds, conversions and refurbishments as a single-point main contractor. Call us on 020 3488 6466 or visit beraticonstruction.co.uk to discuss your project. Our office is at 12 Cecil Road, London NW10 8UJ.
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