Commercial Formula of a complete product unit value determination (of a complete prefab house kit –with strengthened structures of roof & floor & with joinery woodworks//of a zero prefab house kit –without strengthened structures & without joinery woodworks) = net price for a section size of the profiled dry timber of wall prefab house set of 28mm & 45mm or 70mm + adding price for strengthened set of roof & floor structures, also cost of joinery woodworks)