Dynamic Wind Uplift Performance of Thermoplastic

Wind dynamics, on a conventional roofing system, lift the membrane and cause fluttering, introducing stresses at the attachment locations. To identify the component of the system that has the weakest resistance against wind uplift forces, a dynamic method of evaluating roofing systems is beneficial. A recent industry survey predicts significant growth for thermoplastic polyolefin #TPO# membranes. Among others, hot-air-weld ability is an advantage of the TPO. In mechanically attached TPO roofs, seams are formed by welding one side of the bottom sheet with the top sheet using hot-air machines. Advancements in welding technology have led to double-side weld procedures or encapsulated seams for the TPO membranes. Wind uplift evaluations are being carried out on the TPO systems with one-side weld and double-side weld. Experiments have been conducted at the dynamic roofing facility #DRF# of the National Research Council of Canada, using the SIGDERS #special interest group on dynamic evaluation of roofing systems# wind test protocol. Systems with double-side weld performed better than the systems with one-side weld. Use of double-side weld minimizes asymmetrical stress concentration and improves the wind rating of the mechanically attached TPO roofing systems