In a recent webinar on cool roofing, a presenter discussed some concerns with the roofing industry’s focus on single-ply roof membranes based on Thermoplastic Polyolefin (TPO). The presenter noted that Hypalon – the trademarked Chlorsulfonated Polyethylene (CSPE) supplied by DuPont – was now out of the U.S. market, a situation that would likely expand the use of TPO-based single-plies.