Abstract: A sheet of expanded metal lath has expanded longitudinal edge margins between which the metal sheet is selectively expanded transversely of the sheet length to define plural parallel rows of trapezoidal openings having long sides of about one inch and widths perpendicular to the long sides of about 7/32 inch. Between the selected rows of the openings, the sheet defines corresponding ones of plural rib constructions, each of which has a generally "Z" transverse cross-sectional configuration having substantially parallel non-coplaner and non-overlapping rib edge portions interconnected by a rib central portion disposed oblique to the rib edge portions. Where the unexpended thickness of the sheet is substantially 0.015 inch, the expanded metal sheet has a weight of substantially 1.8 pounds per square yard. The article has about 70% "openness", yet has adequate resistance to bending about lines across its width due to the configuration of the ribs and the sheet edge margins.