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Evaluation of the effects of long term UV exposure on single ply membranes

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Abstract
The ability of a single ply membrane to maintain its initial physical properties over an extended period of time can be a predictor of performance. Identifying and measuring how these properties change has been the subject of prior research. Jim D.Koontz & Associates, in conjunction with Target Corp., undertook a 1-1/2 year study to evaluate the relative performance level of eleven single ply membranes when subjected to long-term ultraviolet (UV) exposure in the lab. New samples of various single-ply membranes wee collected from seven different single ply manufacturers. Relative performance attributes have long been recognized in the roofing industry as a critical part of comparing and evaluating roofing membranes. On average, the TPO membranes have a greater propensity for retaining physical properties when compared to PVC, KEE, and EV membranes. Substantial variations, however, were observed within the TPO group. Of the eleven single ply membranes tested, significant variation exists in how the products performed. The loss of thickness in a PVC sample was the greatest at 8.9% compared to one of the TPO samples that gained a slight amount of thickness at 0.9%. The increase in brittle point temperature ranged from a low of 16.1 C° (29.0 F°) in a TPO sample to a high of 75 C° (135 F°) in the EV-based sample. Single ply manufacturers have, most likely, performed in-house testing on their products and are aware of the relative long-term performance characteristics of their products when compared to other manufacturers’ products. Typically the manufacturers only provide the initial product characteristics at the time of manufacturer. The long-term performance data should be made available by the manufacturers to owners, designers and contractors so that informed decisions can be made in the selection of single ply products.
Date
0/0
Author(s)
Jim Koontz; John Erland
Page(s)
Keyword(s)
UV exposure; single ply; PVC; KEE; TPO; Target Corp.


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