If the length of the roofing trays is over 1,5m the clips used to secure them to the substrate must allow the zinc to expand and contract, and these trays use a combination of fixed clips and sliding clips to accomplish this.
The position of the fixed clip zone depends on roof pitch – to avoid the trays from buckling, the steeper the pitch, the higher the anchoring band of fixed clips is positioned. The thermal movement generated in the trays is accommodated by a gap introduced in the detail at the foot and at the head of the trays.
The standing seam, angle seam and flat lock panel systems all use the same set of seam centres, which are tied into commercially available coil widths. Therefore, the following table can be used to determine the bay widths, thicknesses, and also to specify the number of fixings per m2 for each of these systems.