Cold Adhesives Increase BUR Options

May 15, 2003

26 • Interface August 2003
Cold application has provided an alternative to traditional hot
asphalt applied built-up roofing (BUR) in the industry for
more than 20 years. The term “cold-applied roofing system”
means that the BUR roofing system is assembled using multiple
plies of reinforcement applied with solvent-borne, bituminous (liquid)
adhesives instead of hot asphalt. In place of hot asphalt,
“cold” asphalt adhesives are applied between reinforced base/ply
sheets to provide a weatherproof membrane. In BUR cold process
roof systems, manufacturers typically require that only fullycoated,
non-porous felts such as standard base sheets be used as
base and ply sheets. Generally, an aggregate
surfacing or a coating is then applied over
the completed membrane to provide protection
and to provide a fire rating for the roof
system.
The Benefits of Cold Process
Applications
In the last several years, the roofing
industry has seen a trend toward an
increased use of cold process roof systems.
When asphalt fumes are a concern, contractors
are turning to cold-applied, asphaltbased
adhesives. This trend is being driven
by the re-roofing market and the sensitivity
sometimes present when installing hot
asphalt roof systems. Since kettles are not
required for cold process roof systems, building
owners are able to execute roofing projects
during the entire year in lieu of
“summer-only” limitations.
The institutional market is taking advantage
of the ease of set-up and staging
required in the application of a cold process
applied roof system. By using a cold process,
there is less concern with the staging of
equipment. In addition, fire safety, odor con-
Roofers using the “mop and flop” method with a BUR cold applied job.
trol, and limited staging areas are easier to
control. Therefore, utilizing cold process
applications provides a greater window of
planning and executing projects. Coldapplied
systems are able to overcome limitations
often encountered with hot
installations and provide an excellent alternative
for building owners and specifiers who
prefer BUR systems.
How the System Works
Cold process BUR is available as complete
systems or as repair systems for new
construction or re-roofing, and they are
available in a variety of constructions.
Roofing manufacturers have developed adhesives
that are effective with both insulation
and roof membrane installations. Manufacturers
have multiple cold process assemblies
that have been tested and approved by
Factory Mutual (FM) and Underwriters Laboratories
(UL). Cold process adhesives with
reduced solvents or volatile organic compound
(VOC) contents also are available for
use in areas that restrict VOC.
Cold process systems provide the same waterproofing protection
as hot applied roof systems. An important difference is the
set-up time for cold process. The ambient air temperature and
humidity determine a cold process roof’s “set-up” time. Normally,
installations in colder ambient air and higher humidity climates
require a longer “set-up” time than installations in drier and more
arid climates. Most manufacturers have products specifically
designed for either summer or winter use. As with all hot or cold
August 2003 Interface • 27
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Roofers laying the cap sheet in cold adhesive using the mop and flop method.
28 • Interface August 2003
roof systems, precautions need to be taken until the roof system
“sets up.” All types of roof traffic must be minimized or eliminated
to avoid interply adhesive displacement.
Installation
Several methods can be used in cold
process roof installations. Adhesives can
either be manually applied with a
squeegee, or brush, or spray-applied
using properly designed spray equipment.
Installers should consult the manufacturer
for recommended spray
equipment. Proper coverage rates are
vital to a successful, long-term, coldapplied
roof system. Both methods
require that the proper amount of adhesive
material be installed. If too little
adhesive is applied, there is a potential
for an improper bond to be formed. If too
much is applied, then the potential for
longer set-up times and membrane displacement
is increased.
Coverage rates are usually between
1.5 – 2.5 gallons per roofing square per
individual membrane layer. The installer
usually marks a roofing square out and
pours the proper recommended amount
of adhesive in the area to ensure proper
application rates. This also allows familiarization
with the required thickness of
the adhesive for recommended coverage
rates. The installer needs to be aware that
different substrate porosities will dictate the
specific coverage rate quantities. Always be
sure to consult the manufacturer for proper
coverage rates and application requirements.
The industry is also starting to introduce
reusable 350-gallon totes as a container for
the adhesive. Totes can be returned and
reused, minimizing the use of valuable landfill
space and the disposal of hazardous
material.
The techniques used in the application of
cold systems are significantly different than
those using hot asphalt. As a result, additional
training is required. Also, it is important
to be aware of the special precautions
that must be taken when using industrial
materials that contain solvents. To decrease
cure time of the adhesives, specific manufacturer
formulations will vary. Again, consult
the manufacturer for guidelines for the
proper and safe recommended installation
process.
Cold process BUR systems now exist
that use coated or uncoated polyester reinforcements,
or composite (polyester/fiberglass)
reinforcements in conjunction with
either solvent-borne or waterborne adhesives. The combination of
reinforcement and adhesive is typically proprietary to the system
provider, and compatibility should be verified with the manufacturer.
Brooming to ensure full adhesion of the BUR felt and respective plies.
Roofer using spray equipment for a cold application BUR system.
August 2003 Interface • 29
BUR has been the most common low-sloped roofing system
in the past, but cold-applied systems have begun and continue
to claim a noticeable share of the BUR market. Cold-applied systems
have proven repeatedly to be an effective and economical
answer to solving the challenges associated with the installation
of new roofing, as well as providing preventive maintenance and
repair for existing roof surfaces.
In the future, we believe that there will be an increased
demand for cold applied bituminous roofing. By combining the
advantages of cold adhesives with the advantages of multiple
plies of roofing membrane, the industry can offer systems with
proven long-term performance that eliminate the dependence on
heating asphalt and the use of an open flame propane torch. ■
David A. Scheirer is manager of the
JM Roofing Institute, an expanded
educational initiative announced by
the company in February 2003. In
this capacity, Scheirer oversees the
well-established Better Understanding
of Roofing Systems Institute
(BURSI) program as well as a program
to provide training to roofing
contractors, distributors, architects,
and engineers, and JM technical
and sales representatives. Scheirer
joined JM in 1982 and has broad experience in all of the
company’s roofing products. He has served as a group manager
in the Technical and Guarantee Services, as a market
manager for each of the company’s roofing membranes, and
as a regional technical representative. Scheirer has a BS in
civil engineering from Tri State University. He is a member
of the Asphalt Roofing Manufacturers Association (ARMA),
Single Ply Roofing Institute (SPRI), and an instructor for
Roofing Industry Educational Institute (RIEI).
ABOUT THE AUTHOR
DAVID A. SCHEIRER
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The Roof Consultants Institute will offer special meetings
and programming in conjunction with the Midwest
Roofing Contractors Association’s (MRCA) Annual
Convention and Trade Show on October 23-24 in
Cincinnati, Ohio. There will be a panel discussion program
on various tentative topics, including:
• Reverse bidding on an Internet-based format for
roofing projects;
• Public purchasing organizations that are purchasing
roofing and roof consulting on a unit cost basis
(AEPA);
• Shop drawings;
• Internet-based roof construction systems;
• Communication between project parties; and
• Proprietary specifications in public bidding.
RCI TO OFFER PROGRAMS AT MRCA