The Self Build Self Help Site retaining wall

A retaining wall is one that holds back an area of elevated ground from a building or part of the plot, either above the proposed house or below it. Quite often the wall will be instrumental in supporting a road above the site. As the availability of plots becomes trickier to find, more often the available plots are on sloping ground, which may require a retaining wall.

At the very start of this topic, an important point must be made - the build of retaining walls is critical and must be designed properly and must then be built to the design. Hence, we cannot here give too much information on the build as it depends on the design. We have included this page to give an idea of what is involved for one particular design.

Your architect will not be able to design a retaining wall - as it requires calculations for load etc. it must be designed by an engineering company - your archtiect will be able to recommend one.

Retaining walls for self-build have tended to be one of two types. A reinforced masonry design which may be a double leaf concrete block structure with steel mesh (also called fabric) in the cavity and filled with concrete. Another design is blocks on flat, 5 or six blocks width at the base and gradually reducing in width towards the top. This is going out of favour and will not often be designed by an engineering company as there is the possibility of shearing between courses.

Another option is precast concrete. JP Concrete offer a range of precast concrete retaining walls. Relative to block work, precast retaining walls are considerably quicker and cheaper to install. They can be bolted down to a secure foundation or cast into a concrete slab. For more information contact JP Concrete Products.

The pressure on a wall can be extreme, caused by pressure from the ground, the weight of water that may lie behind the wall and by ground movement exacerbated by water build up behind the wall. So there is an emphasis on reducing the water that may gather behind the wall through backfilling with clean stone and by ensuring that any water drains away well via weep holes and/or a land drain.

The following pictures illustrate some features of a retaining wall of the reinforced masonry design. - click on the photos for a larger view

photo of retaining wall in preparation

The steel mesh in the trench - as well as reinforcing the concrete, the mesh provides a support to tie in the starter bars. Care is taken to ensure no mesh is contacting the ground.

photo of retaining wall in preparation

The starter bars are left projecting from the concrete and are later tied to the steel mesh in the blockwork cavity.

photo of retaining wall in preparation

This photo shows the amount of concrete foundation towards the supported ground - a good amount of "toe" on which the ground will bear down when backfilled, to further keep the foundation and wall from leaning out.

photo of retaining wall in preparation

One leaf blocks upright, one leaf blocks on flat - in between there is the mesh, tied to the starter bars.