Highly-open longitudinally-stiff, expanded metal product

An article of manufacture comprising expanded metal lath useful as a construction material to serve as a substrate and reinforcement for plaster applied thereto, the article being provided as a substantially rectangular lanced and expanded metal sheet of selected length and width dimensions and having an unexpanded thickness of substantially 0.015 inch, the article having a width substantially greater than an unexpanded metal sheet from which the article is manufactured, the article having unexpanded edge margins of selected width along each longitudinal edge, each edge margin being contoured transversely of the article to define a transversely effective stiffener and each stiffener is contoured to mate with the contour of either edge margin of another similar article, the article between the edge margins defining longitudinal rows of similar substantially trapezoidally shaped openings in which the long side of each opening are disposed substantially transversely of the article, the long side of each opening having a length of substantially one inch and the distance normally between the long sides of each opening is substantially 7/32 inch, the article having a width of substantially 36 inches and a weight of substantially 1.8 pounds per square yard of area, the article also defining between the edge margins a plurality of rib constructions which are disposed parallel to the edge margins and which extend between the ends of the article and which are spaced at regular intervals across the width of the article between selected rows of openings, each rib construction having along the length thereof a three-dimensional stiffening contour which, in cross-section transversely of the length of the article, is of generally "Z" configuration having two spaced substantially flat and substantially parallel but non-coplanar and non-overlapping rib edge portions interconnected by a substantially flat rib central portion disposed obliquely to the edge portions via bend portions which have arcs of substantially 45.degree., the rib edge and the central portions having widths transversely of the article which are substantially three times the thickness of the unexpanded metal sheet.