They aid in flight, thermal insulation, and waterproofing. Damp proofing is another aspect of waterproofing. It has a barrier coating for waterproofing. It is used for repairing and waterproofing metal roofs. Its flat roof was also made of concrete, topped with bitumen waterproofing. There are various cementitious coatings that can be used as waterproofing. The Mesopotamians used the bitumen for waterproofing boats and buildings. PET is also used as a waterproofing barrier in undersea cables. In addition, many synthetic fibers offer consumer-friendly functions such as stretching, waterproofing and stain resistance. Another specialized area of waterproofing is rooftop decks and balconies. It ages very slowly through volatilization and is an excellent waterproofing and oil resistant product. Wood also provided pipes, dye, waterproofing materials, and energy for heat. It is also used for conditioning and waterproofing leather. Second is to separate the waterproofing and trench drain. Others include protection, sensory purposes, waterproofing, and camouflage.