Expansion joint for plaster walls

Abstract

A unitary extruded plaster screed expansion joint for use in cast wall construction. The expansion joint includes a front wall and a first pair of opposing side walls extending rearwardly from the outer edges of the front wall. A second pair of opposing side walls extends rearwardly and outwardly from the rear edges of the first pair of opposing side walls. A pair of planar flanges extends laterally from the rearmost edges of the second pair of opposing side walls, and an inwardly and rearwardly arched wall connects the second pair of opposing side walls. The expansion joint is attached to a support surface, and plaster slabs are formed in place on the support surface adjacent to the expansion strip. The front wall is attached to the side walls of the expansion strip in such a manner as to prevent plaster residue from accumulating at the junctures therebetween, so that when the front wall is stripped away from the expansion joint, no plaster residue remains. As the adjacent plaster slabs expand, the forces brought to bear on the side walls cause the arched interior wall to deform; but since the arched wall is disposed rearwardly and outwardly of the first pair of opposing side walls, the joint is capable of complete closure until the first pair of side walls touch one another. Since the design of the joint affords a greater range of motion, fewer expansion joints can be used to accommodate the same amount of expansion; or, in the alternative, the same number of separators can be used but with narrower joints.