Observe the technical constrains of the assembly instructions! The carrying capacity of the roof covering and substructure must be checked statically by the installer. For roof leaks is no warrenty. Required raised bead width from 15 - 40mm. The self-drilling screws 5.5x25 (6900600011) are for sheet thickness (steel / aluminum) suitable from 0.5 - 1.5mm. There will be 2 self-drilling srews 5.5x25 needed per part.