The two 25 mm high ribs in the latitudinal section of each sheet improves the inertia momentum, thus this form is more enduring than the liner standing seam sheets. Sheets whose thicknesses are determined according to the purlin spans can be produced as one piece up to 60 meters length. 25/490 trapezoidal standing seam is especially developed for industrial buildings with low pitched roofs and arc roofs with wide purlin spans.