Union Corrugating supplies both exposed fastener and concealed fastener metal roofing systems for residential, commercial, and post-frame roofing applications. Exposed fastener metal roofing products and materials are economical, have been in service for decades, and are extremely popular in a wide variety of roofing applications. Concealed fastener metal roofing products give standing seam panels very clean, aesthetically pleasing lines and exhibit the very best in weather resistance and durability.