The present disclosure relates a joint support that includes a support strip having first and second elongate flanges, the first and second elongate flanges having an inside surface, an outside surface, an inner edge, and an outer edge. The joint support further includes a first auxiliary flap including an inner portion attached to the inside surface of the first elongate flange and an outer portion that extends laterally beyond the outer edge of the first elongate flange. The joint support further includes a second auxiliary flap including an inner portion attached to the inside surface of the second elongate flange and an outer portion that extends laterally beyond the outer edge of the second elongate flange. The joint support further includes a pressure sensitive adhesive substance disposed on at least a first portion of an inside surface of each of the first auxiliary flap and the second auxiliary flap.