ANALYSIS
Metal roofing products are generally referred to as being “structural” or “architectural”. Structural refers to roof systems which can directly bare weightloads which are placed on the roof. This means that they can be installed over purlins or lathe boards which run horizontally across the roof trusses. When a weightload is placed on structural metal roofing, the roofing panels bare whatever weight is between the spacing of the purlins. Architectural metal roofs, on the other hand, are installed over solid decking, typically either plywood or oriented strand board. Because architectural metal panels do not span any distances, they do not directly bare any significant weightload, instead passing it down through to the roof decking. If desired, structural metal roofs can also be installed over solid decking. Architectural metal roofs, on the other hand, should never be installed over purlins or lathe boards.
