Thicker isn't better.. "Better Is Better"!

KEE Single Ply Roofing Membrane

The original acronym used to differentiate KEE technology from conventional vinyl technology was EIP (i.e. ethylene inter-polymer). The few associated with the development and introduction of EIP roofing membranes in the early 1980s contended that thicker was not necessarily better—rather, ‘better’ was better. This claim was not without precedent. The actual foundation for EIP roofing was laid in 1974 with the introduction of a geomembrane that pioneered the use of a proprietary KEE vinyl modifier to create a high-performance and chemical-resistant membrane for environmental applications.

Depending on the internal fabrics or reinforcements, initial impact resistance may be improved with the additional mass when testing new membranes. However, roofing membranes anchored to low-molecular-weight liquid polymeric technologies are known to be prone to loss of flexibility due to plasticizer migration. This has been, and will continue to be, a factor affecting in-situ performance of PVC roofing systems.

Today, the thickness paradigm is rampant and crosses all polymeric materials. Is the push for thicker membranes really necessary? When consideration is given to the roofing industry’s new obsessions with sustainability, the question is not just whether these thicker materials are relevant to performance, but also if they can be stewards of our limited natural resources.

By definition, a true KEE membrane does not have to be thick to exhibit very desirable membrane attributes or retard the loss of some migratory component. KEE does not migrate, and a bonafide KEE membrane with a minimum thickness of 0.81 mm (0.03 in.) has demonstrated its ability to remain flexible and endure in harsh environments for more than 25 years. The membrane’s strength attributes come from the fabric, not its thickness. If the fabric is properly engineered, then the coating’s purpose is to protect the fabric’s inherent attributes. Of course, the coating does have to endure the effects of time—and with roofing, time is brutal.

To a certain degree, some additional thickness is understandable in light of the ever-increasing expectations with regard to the tenure of commercial roofing warranties and their associated liabilities over the same period. To assume ‘two times the thickness’ equates to ‘two times the design service life’ may just be wishful thinking. The empirical data regarding the actual service life of these thick (and generally overweight) sheets is lacking.


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About Mr FiberTite

After 10-years in Local 88 out of Canton Ohio, the opportunity to drink the FiberTite Kool Aid came in 1984.  Since then I've been a student as well as a teacher in all manner of roofing with a focus on the engineering, design and installation of thermoplastic single ply roofing systems.  The industry is growing in complexity so there's plenty of opportunity to learn and sharpen your skills no matter who you are.  Hence, one of the most important things I've learned is that "to sharpen the blade, you have to rub steel with steel".


FiberTite® is a Registered Trademark of Seaman Corporation.  The views and opinions expressed on this site are not necessarily those of Seaman Corporation.

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