A self-adhesive tape particularly suitable for use in the building industry for joining and sealing PVC sheets, comprising 100 parts by weight of a vinyl chloride/vinylisobutylether copolymer, from 100 to 400 parts by weight of a mixture of nitrile rubber and a polyvinylchloride homopolymer, from 60 to 230 parts by weight of a plasticizer consisting of one or more esters of phthalic acid, and from 4 to 70 parts by weight of a resinous plasticizer which is an aromatic polyether, an epoxy resin or a mixture thereof, and which imparts adhesive properties to the composition.