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Structure and support

Below-Ground Structures, Earth Retention and Water Control

Retained ground pushes sideways, and it holds water. Every system here is shaped by those two facts arriving at once: a basement box, an embedded wall installed before the ground in front of it is dug away, a gravity or cantilever wall resisting overturning by weight or by leverage, reinforced soil made into its own retaining mass. The freestanding boundary wall is included precisely because it retains nothing, which is the clearest way to show what retention changes.

The three water control strategies — an applied barrier, water-resisting concrete, and a drained cavity that manages water rather than excluding it — are treated as systems in their own right, because each implies a different attitude to the water that will arrive. Shallow foundations sit with ground interfaces, and land drainage sits with site drainage. No entry states a retained height, a waterproofing grade, or any assurance that a buried structure will stay dry.

8 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.

  • Basement and buried structures and the walls that retain ground around them
  • Gravity, cantilever, embedded and reinforced-soil retention, and the wall that retains nothing
  • The three below-ground water control strategies and how each treats water that arrives
  • Not covered: earth pressure calculation, retained heights, waterproofing grades or guarantees

All entries

Every below ground & retaining entry

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

Basement Structure →The below-ground structural box in which perimeter retaining walls, base slab and floor plates prop one another, rather than standing as separate walls and slabs.Cantilever Retaining Wall →A reinforced stem rising from a wide base slab, in which bending strength in the stem and the weight of soil bearing on the heel together resist the retained ground.Drained Cavity Protection →A below-ground approach that admits water, intercepts it on the inside face with a studded membrane, collects it in a perimeter channel and removes it to a discharge point.Embedded Retaining Wall →A retaining structure whose elements are bored or driven into the ground before excavation, taking resistance from the length still buried below formation level and from any propping.Gravity Retaining Wall →A retaining structure that resists retained ground chiefly through its own weight and the width of its base, assembled as masonry, mass concrete, stacked units, filled baskets or crib elements.Reinforced Soil Wall →A structure in which reinforcement laid between compacted layers of fill makes the fill itself the retaining element, while the visible facing holds only the material immediately behind it.Barrier Waterproofing →A below-ground protection approach in which a continuous applied sheet, liquid or slurry barrier is placed against the structure, on the water-facing side or on the inside face.Integral Water-Resisting Structure →A below-ground approach in which the concrete structure itself provides the resistance to water, through the element, its crack control and the treatment of its joints and penetrations.

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.

Retaining structure discussion preparation →Questions to prepare before a retaining structure conversation.Below-ground water questions →Preparation for a discussion about water in the ground.Retaining wall materials →The choosing-and-comparing side of retaining wall materials.

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.Sealants & Membranes →Reference entries for the thin control layers — joint sealants, damp-proof courses and membranes, vapour control layers, breather membranes, tanking systems, tapes and foams.

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 →