Retaining wall

A retaining wall holds back soil between two different ground levels. It is used to create level areas on a sloping site, to make room for a road or building, or to secure an embankment. The soil behind it pushes sideways all the time, and the wall resists that pressure through its own weight, its foundation and its reinforcement.

Types of retaining wall

Gravity walls rely on mass, using heavy materials such as stone, concrete or gabions. Reinforced concrete cantilever walls work as an inverted T, with a base slab and stem, and can retain greater heights with a thinner section. There are also reinforced soil systems, geogrid-reinforced block walls and anchored walls. The choice depends on height, soil properties and the loads above. Sizing needs a structural calculation based on a geotechnical survey. Water building up behind the wall is the most common cause of failure, so a drainage pipe, filter material and weep holes are placed at the back.

Retaining walls in landscape and visualization

Retaining walls are central to terraced gardens, ramped entrances and hillside housing. In a render, the wall’s material, the planting along its top and the railing at the edge set the depth of the scene. For sloping residential schemes, see 3D residential site design.