Small retaining walls have to be drained

Drainage on a retaining wall - this is what you should know

Need for drainage

Every retaining wall needs to be backfilled so that it can even serve its purpose. Another fundamental function of a retaining wall is to keep the area behind the wall (embankment or backfill) sufficiently dry.

In many cases this can be done without drainage. The decisive factor is always the specific situation at the construction site. Basically, you always need drainage

  • Retaining walls are over 120 cm high or
  • the soil quality is correspondingly poor (low infiltration capacity) or
  • with existing embankments that are above the wall or
  • in the case of retaining walls staggered one after the other (usually not the case in the garden area)
  • it is a commercial project (i.e. in the commercial and municipal sector) - drainage systems are always installed here because this is mandatory)

The on-site situation is therefore always decisive for the need for drainage. If you are not sure, have a specialist check the groundwater situation before planning and adhere to the plan specifications.

Groundwater must not come into contact with the wall elements or with the backfill (take into account the highest measured groundwater levels!). Should such a situation exist Planning of the wall by a specialist (engineer) is imperative!

Correct execution of drainage

Basically, when draining the wall, you should make sure that the backfill is inside all cavities and at least 300 mm behind the wall elements [/ strong] is filled with suitable ballast. This means that surface water that has seeped away (attention: groundwater may not be present!) Is discharged through the backfill.
The drain pipes are installed at the foot of the wall (below the top edge of the foundation or on the foundation). The position of the drainage pipes is different, depending on whether drainage is being carried out towards the front of the block or towards a lower point.

Planning a functioning and effective drainage system can in many cases be a complicated matter. Whenever you are unsure, it is best to seek advice from a professional. In many cases, a soil survey will also be necessary to determine the seepage capacity of the soil and the correct dimensioning of seepage.

Author: Johanna Bauer Home »Building» Water »Drainage