The thickness of the material. The roof created of metal profile is often subjected to all kinds of mechanical loads. So that it does not deform and does not become unusable, the thickness of the layer should be at least 0.4 mm. The optimal thickness of the profile elements is 0.5 mm. Options for such a metal tile can be watched here or in the cabin of building materials of your city. Such a thickness will maintain the plasticity of the material along with the necessary stiffness.