Thermal Plastic Olefin or TPO is slated to be the roof of the future, it is also referred to as a “Single Ply Membrane” as it is an entire roofing system in one ply. Depending on the deck type different preparation methods are used and different TPO variants are used. GAF makes three variations of TPO with different thicknesses that are measured in Millimeters. There is a gray material that constitutes the bottom side of the material, it is reinforced with a fiberglass grid that is sandwiched between the gray bottom and the white reflective top. Depending on the deck type the TPO is adhered using different methods, but the system is considered monolithic because it is welded together at the seams where the rolls over lap, this ensures that no moisture can penetrate the system and that the system will not fall apart over time. The welding of the seams are performed in 1 of 2 ways using a hand welder which is essentially a hot air gun used for details and a robot welder which is used for long runs. After each pass of the welder a roller is used to press down the seams and remove any air that may become trapped, after that a small hook is ran along the seams to ensure that everything was properly welded, and when an inconsistency is found it is marked and re-welded. Although this process is less labor intensive than a BUR system the TPO system is more detail intensive.
TPO excels where BUR comes short. With its highly reflective white surface it can greatly reduce energy costs for a building because the TPO stays at about 100 degrees Fahrenheit on a 90 degree day. Another great benefit is that the TPO system is not affected by ponding water in any way, as a matter of fact the manufacturer suggests that the roof be cleaned with a pressure washer which can damage other roof systems. If a roof has issues with ponding water tapered insulation must be installed on a BUR system so that the water can run off the roof and not have it affect the system. Tapered insulation is very expensive in material and labor cost; as the TPO is not affected by ponding water tapered insulation is not required and greatly reduces the cost of the roof system. It can be said that if both roof systems are installed properly the roof can have a life span of 20 years.