The double standing seam is formed by locking the sides of adjoining panels by double welting the top of the upstand of the seam. The standard panel width is 530 mm, the height of the seam is approx. 25 mm. The minimum roof pitch is 3° (5.2%), a fully supporting substrate is requiered. Special shapes such as convex and concave curves or tapered panels can be produced without any problem.