Waterproofing: What Went Wrong?

Only one correct element is visible in this image: the sealing tapes designed for waterproofing the construction joint are positioned along the centerline of the wall. However, neither the left tape nor the right tape has been installed correctly.

• On the left tape, the lower part appears matte, which is the section that should have been embedded in the concrete slab. This indicates that the tape was placed too high or was lifted during concreting.
• On the right tape, too much of the tape is submerged in concrete—at least twice as much should be exposed.
• Additionally, the right tape still has transport film attached, which should have been removed before concreting.

Most importantly, the two tapes have not been connected. The left tape was not welded to the right tape, meaning there is no proper waterproof seal at the junction between the bottom slab and the walls.

How Can This Be Fixed?

• The first step is to cut out and remove the incorrectly installed tapes.
• Then, an injection hose must be placed and the walls must be concreted.
• Finally, an injection sealing process is required.

This means that instead of a relatively low cost of a few dozen złoty per meter for properly installing the tapes, the cost now rises to 200-300 zł per meter for sealing through injection.

This example highlights why proper waterproofing—from planning to execution—is critical. Even the smallest mistake can lead to significant additional costs.