Waterproofing of raft foundation

Common issues and queries you can face

Waterproofing of raft foundation

Waterproofing of immersed underground structures requires permanent dewatering during the execution phase and continues until the pressure caused by the weight of the concrete structure exceeds the hydrostatic pressure exerted by the water table.

The types of foundations designed for such structures is most of the time raft foundation with or without piles, or a combination of the raft and pile caps, depending on the bearing capacity of the soil. In such cases, the waterproofing is called tanking as it envelops completely the structure from the bottom to the water table level and preferably to the ground floor level. The waterproofing of the vertical part will start only when the full foundation raft/pile caps are cast. 

Step by step solution

weber solution

  1. Pile head waterproofing

    The head of the pile should protrude by 20 cm higher than the blinding level. First, repair the pile head to provide a leveled and high strength capping. Then finish pile capping with an epoxy mortar.

  2. Horizontal part of tanking under foundation

    The surface of the blinding should be dry, smooth, plane and free from any obstacle that might puncture the waterproofing membrane.