Double Standing Seam offers most of the benefits and qualities of Angle Seam, however Double Standing Seam involves a double process for closing the seam, which works best with softer, more malleable, raw metals such as Copper and Zinc, as painted finishes can become stretched and microcrack the paint finishes. Prefa Aluminium is designed for Tray and will show the least microcracking of painted metals. New Zealand painted aluminium metals have higher tensile strengths and can show more paint stretching. It is not recommended that painted steel products are used with this design.
There are a number of roof mounting systems for access and services. For example Photovoltaics can be fixed to Double standing seam, or single seam roofs can be double seamed just where the clips are placed.
Metals used for the manufacture of Double Seam:
Unpainted and painted Aluminium (Prefa), Raw copper, Raw and painted zinc (VM Zinc). Some micro-cracking of paint finishes might occur.