Application of polyurethane waterproofing system on slab-roof with existing asphalt. The substrate was primed with epoxy water-soluble primer followed by waterproofing with ISOFLEX PU-510, in two coats. For greater elasticity and further protection of the waterproofing from the sun radiation, the aliphatic polyurethane coating TOPCOAT-PU 720 is applied at the end.