Changes have been made to the U.S. product standard for TPO roof membranes that should result in some improvement to their performance. If you are involved in the design and installation of TPO roof systems, you should be knowledgeable of these changes and be aware additional improvements still are necessary.
The U.S. product standard for TPO roof membranes is ASTM D6878, "Standard Specification for Thermoplastic Polyolefin Based Sheet Roofing." ASTM International originally published the standard in 2003 and revised it in 2006 and 2008.
This year, ASTM D6878 was revised twice. With the first revision, which was balloted by ASTM International in April, the duration of specimen heat aging before aged physical property testing was increased from 28 days at 240 F to 224 days at 240 F, an eight-fold increase. The physical property evaluation methods after heat aging remain unchanged.