Choosing the right foundation type is one of the most important decisions in any construction project. The two most common options for residential builds in Brighton and East Sussex are raft foundations and strip foundations. Each has distinct advantages depending on your site conditions, building type, and budget.
What Is a Strip Foundation?
Strip foundations are continuous strips of concrete that run beneath load-bearing walls. They transfer the weight of the structure to the ground along these linear paths. Strip foundations are the traditional choice for most UK residential buildings and are effective when ground conditions are stable and consistent.
For most standard foundation projects in Brighton, strip foundations are cost-effective and well-understood by building control.
What Is a Raft Foundation?
A raft foundation is a large concrete slab that spans the entire footprint of the building. It spreads the load across a much wider area, making it ideal for sites with weaker or variable ground conditions. Raft foundations are increasingly common in Brighton, particularly on clay soils or sites near trees.
Key Differences
| Factor | Strip | Raft |
|---|---|---|
| Best for | Stable, consistent ground | Weak or variable ground |
| Depth | Typically 600mm–1m+ | Shallower, 300–500mm |
| Excavation | Trenches only | Full footprint |
| Cost | Lower for simple builds | Higher material cost, but can save on excavation |
| Speed | Standard | Often faster overall |
Soil Conditions in East Sussex
Brighton and surrounding areas sit on varied geology. The chalk downland provides excellent bearing capacity in many locations, but areas with clay—particularly Weald Clay in Haywards Heath, Burgess Hill, and Horsham—can be prone to shrinkage and heave, making raft foundations the safer choice.
Which Should You Choose?
The decision ultimately comes down to a site investigation. A trial hole or bore hole reveals ground conditions, and your structural engineer will specify the appropriate foundation type. At Masters Group, we carry out foundation assessments as part of our new build and extension services, ensuring the right solution from day one. For a detailed cost breakdown, see our guide: new build costs in Brighton.
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