Underpinning: more than 40 years of experience

Underpinning makes it possible – in a dry subsoil – to safely underpin and deepen existing foundations or columns. We have a safe solution for any existing wall or foundation thanks to our experience in underpinning that stretches back for more than 40 years.

As a member of ABEF (the Belgian Association of Foundation Contractors), CVR participated in meetings of the ‘underpinning’ working group of the BBRI. This working group forms the basis of the implementation sheet underpinning. We carry out our activities in accordance with this sheet.

How is underpinning executed?

  1. Excavating underpinning is done with the shored trench method. We make a distinction here between primary and secondary phases.
  2. First, we undermine the existing wall or foundation over a limited width to the required depth. During digging, we sheet the outside of the trench with prefabricated concrete slabs. We sheet the other three sides of the trench with timber.
  3. Our sheeting method ensures that the sheeting is immediately clamped against the underlying soil (shore wall). Thus we avoid ground stress relief and minimise the risk of settlement of the underpinned building.
  4. We repeat this process until we have reached the required depth.
  5. We subsequently build the new concrete wall in the shored trenches. To do this, we provide the necessary reinforcement. We install the connecting reinforcement to the trench side joints. If possible, we provide the necessary connecting reinforcement for the floor slabs. The specially designed form panels guarantee perfectly smooth walls in the trenches.
  6. Once the concrete has hardened, we dismantle the wall and shore it up again against the timber sheeting.
  7. For the secondary trench, we install a prefabricated concrete slab behind the already concreted primary segments. The sheeting beams are installed behind the primary segment sheeting.
  8. We then provide reinforcement and shuttering and pour the concrete.
  9. The last step is dismantling the constructed wall and sheeting it against the timber sheeting.
  10. When we excavate the construction pit, the walls must be anchored or shored up, depending on the depth. During the construction pit excavation, the sheeting timber has to be recovered.

What are the benefits of underpinning?

  • Underpinning avoids loss of space in the building being constructed.
  • The underpinning can be executed from any basement of standing height and in almost any subsoil.
  • Provided special measures are taken, the installed underpinning is perfectly suitable as definitive basement walls.
  • There is an exceptional degree of freedom of execution with underpinning.
  • Underpinning cannot support sandstone or foundation masonry.
  • A possible option is to first stabilise the existing buildings with micro piles, and subsequently carry out the underpinning.
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