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SBS Modified Bitumen
Specifications |
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Specification (SPEC. ID
- C2) |
Squeegee Method
Two-Part Cold Adhesive SBS Modified Bitumen Roofing System (Refer to the
hot mopped membrane specification for diagram.) For use as an alternative
application method to hot asphalt applied SBS modified bitumen membrane
specifications.
For Regions 1, 2 and 3
The adhesive is applied at a rate of approximately 1 to 2 gallons per square over
non-porous substrates, e.g., primed concrete or fiber glass base felts. If over porous
materials, such as insulations, the application rate will increase to approximately 2 to
3 gallons per square or more depending on the absorbency of the material.
General
This specification employs a cold adhesive, JM MBR Bonding Cement, as a direct
substitute for the Type III and IV asphalts used in hot application of modified bitumen
roofing specifications. JM does not recommend the use of traditional asphalt cutback
cements and mastics to bond SBS products to any substrate. MBR Bonding Cement
is a two component, elastomeric adhesive, consisting of a base material and an
activator. It is ideal for applications where hot asphalt is undesirable or prohibited.
This specification is intended to be used over JM roof insulations or other approved
roof insulations which are not nailable and which provide a suitable surface to receive
the roof. Specific written approval is required for any roof insulation that is not
supplied by JM. This specification may also be used over any type of approved
structural deck which provides a suitable surface to receive the roof. Poured and
pre-cast concrete decks require priming with JM Concrete Primer. The primer must
be completely dry before adhesive application begins.
Note: All general instructions contained in the current JM Commercial/Industrial
Roofing Systems Manual shall be considered part of this specification.
Design and installation of the deck and/or membrane substrate must result in
the roof draining freely, to outlets numerous enough and so located as to
remove water promptly and completely. Areas where water ponds for more
than 24 hours are unacceptable and will not be eligible for a JM Roofing
System Guarantee.
Flashings
Flashing details can be found in the "Bituminous Flashings" section of the JM
Commercial/Industrial Roofing Systems Manual.
Application
On roof decks with slopes up to 1/2" per foot (41.6 mm/m), the roofing felts and
modified bitumen sheets may be installed either perpendicular or parallel to the roof
incline. Follow the specific felt lay-up prescribed in the hot asphalt version of the
desired specification.
JM MBR cement products are significantly different from the adhesive materials used
for built-up roofing. The mechanic must use a great deal more care since these
adhesives are prepared on the job site. Roofing contractors must advise their crews
to precisely follow all storage, handling, preparation, application, and health/ safety
instructions. JM will not accept responsibility for any use of these products that does
not comply with the instructions printed on the cement base container.
For specific and detailed information on the mixing and application of MBR Bonding
Cement, and the construction of this specification, refer to Paragraphs 7A.14 - 7A.25
in the current JM Commercial/Industrial Roofing Systems Manual.
Surfacing
Refer to the appropriate hot application specification.
A heavy coating of adhesive may be applied over smooth surfaced products. Roofing
gravel or granules may then be embedded in this coating.
If reflective coatings are to be applied to smooth surfaced, modified bitumen sheets,
make certain that any residual adhesive bleedout at the laps has been removed and
the area is completely dry. Bleedout material may impede adhesion or cause staining
of the reflective coating. The coating is to be applied in accordance with the
manufacturer’s application instructions.
