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Structure and support

Foundation and Ground Interface Systems

Every entry in this family answers the same question a different way: how is the weight of a building handed to the ground beneath it, and what does that ground do in return? A strip spreads a line of load, a pad collects a point, a raft treats the whole footprint as one element, and a pile reaches past the surface to something more dependable. Which of them applies is decided by the ground, not by the building above it.

What sits outside this category is the structure arriving from above and the water arriving from the side. Frames and load-bearing walls are described under primary structural systems; basements, retaining walls and the waterproofing of buried structures belong with below-ground and earth-retaining systems. Ground investigation, bearing capacity and foundation design are engineering work, and nothing here substitutes for a qualified professional doing it.

7 system entries · educational assemblies reference · how a system performs always depends on the whole building and qualified professional design

Scope

What this category covers

Where the boundary of this part of the encyclopedia sits, including what it deliberately leaves to qualified professionals.

  • Shallow foundations that spread load across near-surface bearing ground
  • Deep foundations and the caps and beams that connect them to the structure above
  • Ground treatment and ground gas protection at the point where a building meets the ground
  • Not covered: ground investigation, bearing capacity, foundation sizing or reinforcement design

All entries

Every foundations & ground entry

The complete set for this category. Frequently referenced entries come first — a starting point, not a ranking.

Strip Foundation →A continuous linear footing beneath a load-bearing wall that widens the load path, delivering the wall line onto bearing ground and forming the place where wall, floor and ground meet.Raft Foundation →A single stiffened concrete plate covering most or all of a building footprint, on which walls and columns bear directly, so that foundation and ground floor become one element.Piled Foundation →A deep foundation that carries load past unsuitable near-surface ground on slender vertical elements, delivering it into stronger strata below or into friction along the shaft.Pad Foundation →An isolated footing beneath a single column or post, spreading a concentrated point load into the ground and carrying the base connection that joins the member above to the foundation.Pile Caps and Ground Beams →The load-collecting layer between piles and the structure: caps over pile heads and beams spanning between them, so walls and columns bear on beams rather than on the ground below.Ground Improvement →Engineered treatment of the ground itself, by densification, replacement, stiffer inclusions or binder mixing, so a shallow foundation can be considered where untreated ground would not carry one.Ground Gas Protection →A gas-resistant barrier beneath and around the lowest floor combined with a ventilated or depressurised layer below it, the pair intended to limit ground gas movement into a building.

Elsewhere on Build Design Hub

Planning guidance for this subject

This encyclopedia explains how these assemblies are organised. These sections help with choosing between them and preparing for the conversation.

Foundation planning basics →The planning side of how a foundation decision is approached.Groundworks conversation preparation →Questions to gather before a groundworks discussion.Foundation condition questions →Preparation for a conversation about an existing foundation.

Materials Library

What these assemblies are built from

A systems entry explains how an assembly is organised. These materials sections describe the substances themselves — what they are, how they behave and what governs their use.

Concrete & Cement →Reference entries for cement-based materials — ready-mixed and precast concrete, screeds, levelling compounds, renders of the cementitious family and the admixtures that modify them.

Building Systems Encyclopedia

Reference entries for building assemblies — how each is organised, what role every component plays, how the parts interact and which junctions matter.

Browse all building systems →