Abstract: A joinder system for providing a seal between a pair of opposed walls is formed to include a sealing element consisting essentially of a body of resilient material having at least one continuous cavity formed internally thereof, with the cavity being filled with an appropriate material under pressure in order to effect flexure of the sealing element during formation of the joint. Adhesive material is applied externally between the outer walls of the sealing element and the opposed walls which are to be joined together. As the filling material is introduced into the cavity of the sealing element it promotes deformation of the external contour thereof in order to adapt the sealing element to the shape of the joint which is formed and in order simultaneously to apply pressure against the adhesive.