Bituthene® Mastic rubberized asphalt-based mastic. It has excellent adhesion to structural concrete, masonry, glass-mat faced gypsum sheathing and wood and is designed to seal terminations, edges of patches, and overlaps in detail areas. It is compatible with all Perm-A-Barrier self-adhered air barrier and flashing membranes. It is an integral part of the Bituthene® Waterproofing System, though it should not be used as a primary waterproofing material. Bituthene® Mastic is architectural and industrial maintenance regulations limit the VOC content in products classified as architectural coatings.