Backfilling the excavation - you should know that

Backfilling the excavation after the completion of the cellar construction is quite a complex matter. Careful planning and very clean execution are necessary here, otherwise the stability of the building may be impaired. What you should definitely know about backfilling can be found in our article.

When to fill?

First of all, the timing is important: Ideally, the backfilling takes place immediately after the sealing material on the cellar wall has hardened. The reason for this is that the basement waterproofing should come into contact with the weather and solar radiation as little as possible so that its sealing function is retained for a long time.

  • Also read - Backfilling the excavation: Why clay causes problems
  • Also read - Backfilling the excavation - you should know that
  • Also read - digging a pit without a building permit - it works?

Backfilling at an early stage ensures that the waterproofing of the basement walls is not damaged. So you have to start backfilling the construction pit accordingly.

In this case, the so-called "work space", as it is called in technical terms, is filled. This is the space between the basement and the edge of the building pit after the basement has been built.

Backfill materials

They are especially suitable for backfilling

  • gravel
  • gravel
  • granules
  • sand

However, the existing excavated soil can also be used, provided it has a sufficiently good quality and only a low clay content.

After all, this reduces the costs for the disposal of the excavation considerably. If the seepage capacity seems too low, you can also add sand and gravel to the soil.

Choosing the right backfill material

The backfill material must always be selected according to the water pressure situation on the cellar walls and the nature of the soil on the building site.

Not all materials have sufficient leachability or can be compensated high enough.


The compaction of the backfill has a crucial meaning, also for the stability of the building. If it comes to settlements later, almost always either an inappropriate chosen filling material or an insufficient compression of the backfühl material is the reason for this.

The filling material is usually introduced into layers of 30 - 50 cm thickness and compressed layer for layer. It is also important to ensure that no water is running between back filling and basement wall seal: in this case, the backfilling would be understuffed and no longer sufficiently compressive.

Tips & Tricks the pit simply with excavation is not a good idea. Let this important work definitely do by professionals. Using the excavation is a very advantageous solution (also in terms of costs) if the excavation is of the right quality.