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Building components

Substructure & Ground Elements

The prepared surfaces, layers and buried members between undisturbed ground and the first structure above it.

18 entries in this category.

Overview

About this category

Below the visible building sits a sequence of prepared surfaces and layers, each defined by what it separates rather than by what it is made from. A formation is a surface, a blinding is a layer laid to protect it, and a sub-base is a layer built to spread load — and none of the three is fully described by naming a material.

These entries explain what each element is for and what it depends on. They do not state depths, compaction, bearing capacities or founding levels: those are project-specific determinations for qualified professionals working from ground investigation.

Boundaries

What this category covers, and what it does not

  • Covers prepared ground surfaces, engineered layers beneath structures and paving, and buried structural members such as pile shafts, pile caps and ground beams.
  • Does not cover foundation SYSTEMS — strip, pad, raft and piled arrangements are building systems, and each is published under /building-systems.
  • Does not cover the concretes, aggregates, geotextiles or membranes these elements are formed from; those are material entries.
  • States no depth, thickness, compaction, bearing pressure or founding level, and makes no determination that any arrangement is adequate for any ground.

Browse

Forms and roles in this category

Descriptive labels for what is here. They are a way of reading the list, not a filter and not a ranking.

Forms:Connector or supportContinuous layerConveyance elementLinear memberUnit or moduleVoid or cavity
Roles:DrainageMoisture controlProtectionSeparationStructureSubstrateSupportTermination

Entries

Substructure & Ground components

Every entry in this category. Each explains what the element is, what it depends on, and how it relates to materials, systems and junctions.

Continuous layerBlinding Layer →A thin layer placed over a formation or sub-base to protect it and to provide a clean, regular surface to work from.Continuous layerCapping Layer →A layer placed over weak ground to create a workable, load-spreading platform beneath a sub-base.Continuous layerEngineered Fill →Material placed and compacted in controlled layers to raise, replace or improve ground so it can be relied upon.Continuous layerFilter & Separation Layer →A permeable layer placed between two different materials to let water pass while stopping fine material migrating into a coarse one.Continuous layerFormation Level →The prepared surface at which excavation stops and construction begins, and against which everything above is set out.Linear memberGround Beam →A beam at or below ground level that spans between foundation points and carries wall or column loads to them.Continuous layerOversite Covering →A covering laid over exposed ground within a building footprint, commonly beneath a suspended floor, to control what rises from it.Connector or supportPile Cap →A block of structure over one or more pile heads that gathers load from above and delivers it into the piles.Linear memberPile Shaft →A slender vertical element taken down through unsuitable ground to transfer load into competent strata below or into the ground along its length.Linear memberRetaining Stem →The upstanding element of a retaining wall that holds back ground and carries the resulting forces down to its base.Unit or moduleSleeper Wall →A low intermediate wall built within a floor void to shorten the span of the floor structure above it.Continuous layerSub-Base Layer →A constructed granular layer that spreads load from a slab or pavement over a wider area of the ground beneath.Continuous layerSubgrade →The body of natural or previously placed ground beneath a formation, whose behaviour governs what can be built above it.Conveyance elementDrainage Sump →The lowest point of a drainage arrangement, where water is deliberately collected so that it can be removed from a single place.Connector or supportGround Anchor →A tension element installed into ground beyond a potential failure surface so that a retaining structure can be held back rather than resisting alone.Void or cavityLight Well →An open recess formed against a below-ground wall so that the room behind it receives daylight, air and an outward opening.Linear memberPool Tank Wall →The wall of a pool tank, containing water on one face and meeting ground or air on the other, and loaded by each in turn.Linear memberRaft Thickening →A deepened zone within a raft foundation, formed under a wall or column line so that concentrated load is spread into the slab.

Related reference libraries

Components are what materials become and what systems are made of. The three libraries answer different questions and are kept deliberately separate.

Materials Library →Building Systems →