What positive water pressure means
With positive water pressure, the water is on the same side as the waterproofing system. The pressure pushes the system against the structure, as it were. An example is the external sealing of a basement wall on the ground side.
This side is not always accessible from existing buildings. Even then, it remains important to understand the source, water level and routes of the water.
What negative water pressure means
With negative water pressure, water penetrates the structure and loads the system from the rear. The water pressure then tries to push the applied layer off the surface.
Adhesion, tensile strength and cohesion of the substrate are therefore extra critical. Not every positive pressure product is demonstrably suitable for negative pressure.
Map waterways
Water can enter through cracks, pour joints, penetrations, floor-wall connections and porous concrete. The visible wet spot does not have to be the same as the point of penetration.
Inspection during different weather or groundwater conditions may be necessary. Active leaks are recorded separately from general moisture transport and condensation.
- Groundwater and rain load
- Cracks and structural joints
- Penetration and bilge
- Capillary moisture
- Condensation and ventilation
Stop active leakage targeted
An active water jet or leaking joint may first require a quick sealing, injection or detailed repair. Then the surrounding concrete is prepared for a wider system.
The chosen approach must take into account continued movement and future water pressure. Only a surface layer over an active point usually does not provide sufficient control.
Check after implementation
Record treated leakage points, joints, layer build-up and quantities used. After relevant rain or groundwater pollution, check again for traces of moisture.
A dry inside immediately after application is not proof of long-term suitability. Observation and maintenance remain part of the solution.
This explanation is general and does not constitute project-specific system advice. Subsurface investigation, tax and official system documentation remain decisive.