Check of layer thickness and thorough drying of waterproofing products

The respect of layer thickness is one of the main issues when waterproofing with cement-based materials or polymer-modified bitumen thick coatings (PMBC) for obtaining a watertight, reliable and sustainable performance when waterproofing basement walls. For this reason, great importance is attached to the minimal layer thickness in the regulations/standards for waterproofing, such as standard DIN 18533 "Waterproofing of Ground-contacting Building Structures", the PMBC guideline "Guideline for Planning and Execution of Waterproofing Works with Polymer-Modified Bitumen Coatings (PMBC)", the FDP guideline "Guideline for Planning and Execution of Waterproofing Works with Flexible, Polymer-Modified Thick Coatings (FPD)" or the MDS guideline "Guideline for Planning and Execution of Waterproofing of Ground-contacting Building Structures with Cement-Based Waterproofing Slurries". All 3 guidelines are issued by the German Construction Chemicals Association.

Whenever using brush-, trowel- or spray-grade cement-based or bitumen-based waterproofing materials, the total layer thickness must be checked in order to guarantee their watertight efficiency. Since the thorough drying depends upon the layer thickness, this must be checked before the excavation will be backfilled.

Step by step

  1. Minimal dry layer thicknesses

    1. The necessary dry layer thickness of all above-mentioned categories of waterproofing materials depends upon water load and material type.


    2. Control of layer thickness with the Weber graduated tool Schichtdickenmesser.


    3. The insertion of the woven glass fiber mesh weber.sys 981 makes visible if the layer thickness is sufficient.


    4. The layer thickness control with the notched trowel weber.sys Schichtdickenkelle is also possible. Whatever the hand angle is, the layer thickness remains unchanged (3 mm). Here with the 2-comp. lightweight bitumen water-proofing thick coating weber.tec Superflex 10.


    5. This special notched trowel allows better layer thickness control also for the 2-comp. reactive water-proofing slurry weber.tec Superflex D 2 or the 2-comp. reactive, thick and quick-setting waterproofing coating D 24.


    6. Smoothing of the second layer weber.tec Superflex D 2 or D 24 (applied with special notched trowel) with flat trowel.


    7. Whenever cement-based water-proofing slurries, for ex. weber.tec Superflex D 2, are applied with flat trowel, their uniform layer thickness can be checked very well with a notched trowel. Here application with the flat trowel weber.sys Aufstreichkelle equipped with the blade Zahnleiste n° 2 (tooth size 5 mm).



    8. Smoothing of the second layer weber.tec Superflex D 2 (applied with notched trowel) with flat trowel.


    9. The complete drying is checked on a sample stone which is deposited near to the building to be water-proofed. Best practice is to lay different layer thicknesses on the sample stone at the beginning of waterproofing works.


    10. After completion of waterproofing works the drying of the whole layer surface is checked by cutting the bitumen layers applied on the sample stone. The bitumen is completely dry when it is black and does not stick to fingers.


    11. Only after complete drying of the waterproofing layers, insulation boards can be applied onto the last waterproofing layer.