Alexandria, Va. (April 27, 2004) — A recent research study published by ASTM1 suggests that single-ply roofing systems such as EPDM may provide equal or better service life as compared to traditional asphalt roofing systems. In addition, the ranking process used in the study places EPDM at the top of the class of modern roofing membranes.
The study measured selected physical parameters of twelve roofing membranes before and after oven heat and ultraviolet exposure. The products tested included multiple-ply roof assembles (two-ply SBS and three-ply BUR), as well as single-ply roofing membranes (EPDM, PVC, and TPO). Each membrane was tested in the same manner under identical conditions to allow for comparison across all membranes tested. Properties tested included load-strain product, cyclic fatigue resistance, water absorption, glass transition, thermal expansion, static puncture resistance, and dynamic puncture resistance. At the completion of testing, test results for each membrane were rated by making the “best” average value in each test equivalent to 100, the “worst” equal to zero, and the remaining results linearly proportioned to these benchmarks.
The following table summarizes the test results from the study:
Roof Membrane / Rankings (100 = “Best”, 0 =”Worst”)
Pre-Exposure After Heat Aging After Ultraviolet Aging
EPDM 76.0 EPDM 87.5 EPDM 75.0
PVC 62.0 PVC 77.3 PVC 69.0
SBS 57.0 SBS 70.0 SBS 59.0
APP 56.0 APP 68.0 APP 71.5
TPO 46.0 TPO 61.0 TPO 45.0
BUR 37.5 BUR 59.0 BUR 58.5
Note: Rankings calculated using the average ranking for all samples tested in the study.
According to the authors, “the EPDM and PVC samples consistently posted the best ratings.” The authors also noted that while this result may be attributed to the strength of reinforcement within each membrane, “the EPDM samples, without reinforcement, consistently rated among the highest in the group.”
The researchers intend to evaluate these same membranes under field exposure conditions in the future, with data collections planned after two, four and six years of exposure. Based on their own experience with the field performance of traditional BUR roofing membranes, the researchers suggest that modern membranes such as EPDM could be expected as to perform as well or better, providing the testing procedures used in the study are predictive of field results.
1. Bailey, D. M., Cash, C. G., & Davies, A. G. (2003). “Service Life Tests for Roofing Membranes.” In W. Rossiter & T. Wallace (Eds.), Roofing Research and Standards Development (5th Ed.). West Conshohocken, PA: ASTM International.