Coal Tar BUR Systems Description Koppers Coal Tar built-up roofing systems consist of alternate layers of Koppers Coal Tar Roofing Pitch and Koppers Reinforcing Felts, topped with a pouring of Koppers Coal Tar into which is embedded an aggregate surfacing. Koppers Coal Tar built-up roofing systems are used on all level or low sloped roofs, and whenever the roofing membrane will be expected to hold water. Slopes for coal tar roofing systems may be up to 1/4" (2%) per foot for Tar-Glas systems and up to 1/2" (4%) per foot for organic reinforced systems. Koppers “GP” systems, which incorporate both tarred organic felts and tar coated fiberglass felts, are limited to a maximum slope of 1/4" (2%) per foot. Review Section 4.6 on Page 8 regarding “Slopes” for coal tar systems.  Return to Built Up Roofing Systems