The project concerns the waterproofing of part of the rooms (surface 1.600 sqm) of the General Hospital of Grevena. The following operations are generally foreseen: Dismantling the cement mortars and the underlying asphalts of the rooms, and construction of reinforced cement mortar. A triple layer of waterproofing membranes will be coated on the entire surface of the new cement mortar, of which the first layer will be adhesive, ventilating, which will abduct the enclosed water vapour from the roof, through roof ventilators, the second layer will be elastomeric, bituminous, sealing membrane and the latter, which will be the final surface of the dome, will be laminated with a pellet lattice. The coatings and seals of the anti-seismic expansion joints will be constructed, additionally, where the drainage of the storm allows it, a small wall, on either side of the joint, on which the joint is placed, after the appropriate sealing of the joint has been done. Dismantling of the existing gutter and reconstruction with its side cover. The gutter will be open, double, rectangular cross-section, and every 7.50 m distance the formation of transverse, rectangular ducts, made of galvanised sheet, of 100*100mm cross section, which will freely channel the water drainage of the roof onto the rooftop The roofs after the interventions will be non-passable, except for the area of the corridors, which will be coated with cement blocks, after being surfaced with geophysics. The entire construction provides for the complete and artificial sealing and fitting of the various materials between them and the sensitive areas (angles, assemblies with endpoints of E/M/installations, etc.).