EPDM Shrinkage

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Author Message Richard Hird (Unregistered Guest) Unregistered guest Posted on Tuesday, August 26, 2003 - 08:02 am:    I recently experienced a problem where an EPDM ballasted membrane had pulled away from the edge opening some seams. It was down only two years. I was told that EPDM shrinks, and "continues to shrink". I am interested in the problem of continued shrinking. Is this true of just "bad" membranes or is true of all EPDM? Has anyone had an experience with this? CJ (Unregistered Guest) Unregistered guest Posted on Tuesday, August 26, 2003 - 11:37 am:    Two years is pretty quick for it to happen sounds like installation error to make it happen that soon. But it does happen all the time to all manufactures in fact they have come up with a new word to discribe it (normalizing). It will normalize forever Anonymous   Posted on Tuesday, August 26, 2003 - 12:25 pm:    Once I learned that heat welding good, chemically adhered seams bad, I stopped specifying EPDM membranes. Why do this when superior single ply products exist at roughly the same cost? The only EPDM membrane I feel comfortable with is fully adhered fleeceback by Carlisle. C. R. Mudgeon Member Username: C_r_mudgeon Post Number: 6 Registered: 08-2002 Posted on Tuesday, August 26, 2003 - 11:59 pm:    The standards that govern EPDM and thermoplastic roof membranes allow shrinkage; I believe it's two percent for EPDM (some manufacturers claim their membranes are more stable). That doesn't sound like much, but it works out to two feet in one hundred feet of roof. "Ballooning" at the perimeter used to be common, but anchoring the membrane at the perimeter seems to have solved that problem. Of course, the stress on field splices remains, so good seams are critical. A seam that is properly done should be able to handle the stress, but since all field work is subject to the uncertainty of weather and labor, it remains a primary source of roof failure. Richard Hird (Unregistered Guest) Unregistered guest Posted on Wednesday, August 27, 2003 - 07:43 am:    Thanks for the responses: No question it was not properly installed. There is lot of other evidence indicating this. The "continues to shrink" still is important to me. Normalizing seems to indicate that it might would eventually become "normal". Will the seams continue to be a problem at the many bad details, or will it stop? CJ (Unregistered Guest) Unregistered guest Posted on Wednesday, August 27, 2003 - 05:50 pm:    If is perfectly dry under the roof (no trapped water) you can get seams to hold. If water is present no chance. repairs will last one at best CJ (Unregistered Guest) Unregistered guest Posted on Wednesday, August 27, 2003 - 05:53 pm:    correction: repairs will last one year at best