Building in Sassoeiros from the 80s had water infiltration in the gutters. After detecting all the pathologies, the entire surface was cleaned and disinfected with a high pressure washer and a sodium hypochlorite solution (1:20). General review of the roof throughout its area, adjusting the positioning of the tiles, correcting areas with potential for infiltration. Application of Krypton Chemical's Imprimación H water-based epoxy primer on gutters and ledges. This primer is designed to receive waterproofing polyurethane membranes as well as to be applied on substrates with a moisture content of over 4%. Finally, application of a quick-drying single component liquid polyurethane membrane Impermax QC by Krypton Chemical in the gutters and platbands. This membrane, due to its elasticity, allows it to absorb the movements of the support, guaranteeing the tightness of the system.