Suggestions & Solutions

Peeling of waterproofing layer: Issue & Solution

Issues and Solutions from Hadjiyiannis!




Peeling of waterproofing layer

Possible causes

The possible causes of this problem can be attributed to the following:

  1. Insufficient cleaning of the ceiling from dust and foreign particles
  2. Failure to use a primer and/or over-thinning the primer
  3. Lack of adhesion of either primer or waterproofing material
  4. Insufficient roof slopes combined with incorrect product selection
  5. Application of the waterproofing material in extreme weather conditions (at a temperature above 35 °C)


  1. First, the loose-defoliated material should be removed. Any repairs that need to be done, must be done before the new waterproofing layer is applied.
  2. Thorough cleaning of the surface from dust and foreign particles
  3. Complete application of the primer on the ceiling
  4. After the primer has dried, a layer of waterproofing sealant is applied along the junction of the roof with vertical elements. While the layer is still fresh, the sealant is reinforced with a strip of polyester fabric or fiberglass
  5. This is followed by universal coating of the roof with the sealant (in at least two layers) and at the same time reinforcement of the first layer with a strip of polyester fabric or Fiberglass mesh. If there are no suitable slopes on the roof, the polyurethane waterproofing ISOFLEX-PU 510 should be used after applying the primer PRIMER-PU 100 by Isomat. ISOFLEX PU-510 has excellent resistance to stagnant water and great adhesion to the substrate. It is also certified with the CE mark as a concrete surface protection product in accordance with the EN 1504-2 standard. For additional protection of the polyurethane waterproofing layer, use the aliphatic polyurethane coating ISOFLEX TOPCOAT-PU 720.
  6. As an alternative to ISOFLEX-PU 510, you can use the water-soluble products ISOFLEX-HYBRID and ISOFLEX-AEGEAN in combination with the primer ISO-PRIMER. ISOFLEX-HYBRID and ISOFLEX-AEGEAN have high elasticity, resistance to stagnant roof water and are also CE marked as concrete surface protection products according to EN 1504-2 standard. ISOFLEX-AEGEAN has the advantage of maintaining its whiteness over time.