HAVE THE ASTM STANDARDS FOR LINEAR DIMENSIONAL STABILITY (FOR EPDM) BEEN MODIFIED?

June 3, 2018

The ASTM standard for linear dimensional stability (ASTM D 1204) was originally 2% maximum. In the mid-90s the standard was changed to 1% maximum. The change in the ASTM standard was influenced by the belief that membrane shrinkage may be a contributor to the bridging seen on some old ballasted applications. In reality, EPDM has always exhibited a dimensional stability value of much less than 1%, even when the ASTM Standard was 2%.