Abstract: A gasket for sealing between a water closet and the floor or other supporting structure. In cross section it includes a flat seat for the base of the closet, an outer flange for sealing against the outer edge of the base and an inner sealing rib formed for hinge-like deflection by and toward the base as the latter is seated. The gasket is adapted to conform to various perimetrical shapes of bases, and may include an integral gasket and sealing section for annularly and sealingly engaging the drain joint of the water closet and the surface of the floor or other supporting structure.