Anomaly Analysis of PVC Roofing Membranes in Portugal

Abstract

Given that PVC membranes are a current solution for waterproofing flat roofs, and their use has been increasing in Portugal, it is important to analyze the main reasons for the occurrence of unusual anomalies in membranes mechanically fastened to the roof (not protected, directly exposed to the normal atmospheric agents) such as the premature occurrence (after less than 8 years old) of very localized dark spots on its surface that are longitudinally along all the rolls of the membrane. An experimental study was carried out and essentially it showed a clear decrease in the thickness of the top layer of the membrane and its total mass in these areas—already with the presence of the knots of the reinforcement mesh on the surface of the membrane, seen through an electron microscope—which is associated with very low levels of plasticizer for the service life of this membrane. From the analysis done, it can be concluded that the defect in question is associated with a less careful formulation of the PVC compound (or mix) during the manufacturing process for unprotected membranes on the roof.