FOR IMMEDIATE RELEASE:             Michael E. Newman
April 11, 1995                     (301) 975-3025
                                   e-mail: newman@micf.nist.gov

                                   TN-6008


           CONSORTIUM TO EVALUATE PERFORMANCE OF
     TAPE-BONDED SEAMS FOR SEALING EPDM ROOFING MEMBRANES

     Five companies and two trade associations have joined the
National Institute of Standards and Technology in a cooperative
research consortium to evaluate the performance of pre-formed
tape for bonding seams in EPDM membranes, a system commonly used
to make low-sloped roofs watertight.

     The EPDM Seam Consortium was established to provide neutral-
party, peer-reviewed performance data on tape-bonded seams needed
by roofing contractors, consultants and manufacturers.  Data
gathered by the consortium will be used to develop a test
protocol and recommended criteria for evaluating the performance
of pre-formed tape systems in EPDM membranes.

     Members of the consortium are ADCO Products Inc., Ashland
Chemical Co., Carlisle SynTec Systems, Firestone Building
Products Co., Genflex Roofing Systems, the National Roofing
Contractors Association and the Roof Consultants Institute.  A
supporting sponsor of the consortium's work is the U.S. Army
Construction Engineering Research Laboratories.

     EPDM, a synthetic rubber (a terpolymer of ethylene,
propylene and a diene) material, is placed in overlapping sheets
to form a membrane atop a roof.  EPDM roofing systems were
introduced in the mid-1970s and, today, account for about 30
percent of the low-sloped roofing systems installed annually.

     Overlapping sheets of EPDM installed on a roof must be
bonded together to ensure a watertight surface.  Solvent
(liquid)-based adhesives formulated with volatile organic
compounds have been the most commonly used bonding agents,
although solvent-free, pre-formed tapes have been available for a
decade.  The current move from liquid-based to tape-based bonding
has resulted from concerns over the effect of VOCs on the
environment.  Other advantages are that tape seams are quicker to
install than liquid adhesive ones, and as a factory-manufactured
product, tape has a uniform thickness.  The trend toward tape is
expected to continue.

     To meet the need for performance data on tape-bonded
systems, the study conducted by the EPDM Seam Consortium will
center on laboratory experimentation complemented by field
inspections.  The former is scheduled to be conducted in three
phases at NIST's Building and Fire Research Laboratory in
Gaithersburg, Md., focusing on creep-rupture testing of tape-
bonded seams.  In a creep-rupture experiment, a seam specimen of
fixed length is stressed under a constant load over time until it
separates.  Better performing seams are those with longer "time-
to-failure" values.

     Phase I of the consortium study will determine and compare
the creep-rupture responses of tape-bonded and liquid-adhesive
bonded seam specimens as a function of load at ambient
temperatures.  Phase II will seek to understand the effect of
factors associated with sample preparation (such as presence of
primer, rubber surface cleanness, pressure, temperature and tape
thickness) on the creep-rupture performance of tape-bonded seams
(with comparisons to data on liquid-adhesive bonded seams).
Finally, Phase III will be an investigation of the effect of
elevated (and possibly, lower-than-ambient) temperature on
creep-rupture performance.

     Concurrent with the laboratory experimentation, field
inspections of EPDM roofing systems having tape-bonded seams will
be conducted.  The roofs selected will be located in a variety of
climates and have considerable age.  Samples of tape-bonded seams
will be taken from these roofs so that their mechanical
properties can be compared to those of liquid-adhesive bonded
seams.

     Each of the first two phases of the study is expected to
last one year.  Based on data obtained, the consortium will
decide whether or not to conduct Phase III.  The completed study
will provide the roofing and construction industry with
recommendations on the general use of tape-bonded seams.  It
also will provide a test method and criteria for evaluating
tape/primer systems, current and future.

     For more information on the EPDM Seam Consortium, contact
Walter Rossiter, B348 Building Research Building, NIST,
Gaithersburg, Md. 20899-0001, (301) 975-6719.

     An agency of the Commerce Department's Technology
Administration, NIST promotes economic growth by working with
industry to develop and apply technology, measurements and
standards.

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