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Johns Manville 2CBN-W/2PBN-W. CSI 3-Part Specifications.
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APP Modified Bitumen Specifications |
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Specification 2CBN-W/2PBN-W |
Two Ply Heat Welded,
Base Sheet Fastened Modified Bitumen Mineral Surfaced Roofing System. For use over Johns
Manville (JM) insulation, approved substrate or other approved insulations on inclines up
to 6" per foot (500 mm/m).
For Regions 1, 2 and 3 |

General
This specification is for use over any type of approved
structural deck with insulation
or approved substrate which is suitable to receive a mechanical fastener and which
provides an acceptable surface to receive the roof.
Specific written approval is required for
any roof insulation that is not supplied by JM.
Insulation shall be installed in accordance with the appropriate JM Insulation Specification detailed in the JM
Commercial/Industrial Roofing Systems Manual. This specification can also be used in
certain reroofing situations. Refer to the "Reroofing" section of the JM
Commercial/Industrial Roofing Systems Manual. This specification is not to be used over
gypsum, either poured or pre-cast, or lightweight insulating concrete decks or fills.
Design and installation of the deck and/or roof
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.
Note: This specification is also for use
with JM PAO (Classic) products.
All general instructions contained in the current JM Commercial/Industrial Roofing Systems Manual shall be considered
part of this specification.
Flashings
Flashing details can be found in the "Bituminous
Flashings" section of the
JM Commercial/Industrial Roofing Systems Manual.
Application
Using one of the base plies listed, mechanically fasten
with an approved JM insulation
fastener and plate a 19 3/4" (502 mm) wide piece of base ply through the insulation.
The remaining base plies are to be applied full width with 3" (76 mm) side and
4" (102 mm) end laps over the preceding sheets. Fasten the laps at 9" (229 mm)
centers, and down the longitudinal center of each felt ply, place two rows of fasteners,
with the rows spaced approximately 11" (279 mm) apart, and fasteners staggered on
approximately 18" (457 mm) centers. Use fasteners appropriate to the insulation and
deck. For additional fastener information, refer to the fastener data in the "Roof
Decks" section of the current JM Commercial/Industrial Roofing Systems Manual.

Heat weld a full width piece of one
of the cap sheets listed so that it is firmly and uniformly set. Subsequent sheets are to
be applied in the same manner, with 4" (102 mm) side and 6" (152 mm) end laps
over the preceding sheets. All laps must be rolled with a 3" (76 mm) rounded edge
roller. A 1/8" to 3/8" (3 mm to 10 mm) bleedout of APP compound shall be visible
at the edge of all seams. All
laps must be checked for good adhesion.
Preparation of the 6" (152 mm) end lap requires
scuffing away all loose
granules. Heat and embed all remaining granules. Apply heat to the roll being seamed while
making sure both have a good compound flow to adhere the two surfaces. End laps must be
checked for proper adhesion.
Application of JM APP/PAO Modified Bitumen Products may
require the use of an open flame
propane torch. Improper use of these materials and application equipment can result in
severe burns, and/or other physical injury, as well as damage to property. In order to
prevent these situations the mechanic must install the materials using the techniques
recommended by JM and those found in "A Guide to Safety: Torch-On Modified
Bitumens" available from the Asphalt Roofing Manufacturers Association. These
techniques have been endorsed by the National Roofing Contractors Association and the
United Union of Roofers, Waterproofers
and Allied Workers.
For special precautions for heat weld application of JM
Classic (PAO) products, refer to
Paragraph 7B.6.6. For cold
weather application techniques, refer to Paragraph 7B.14.
Steep Slope Requirements
Special procedures are required on inclines over 2 1 /2" per foot (208 mm/m). Refer to Paragraph 7B.12.
Surfacing
No additional surfacing is required.
Note: When using metric and English sized sheets in the
same system, care must be taken
to avoid lap over lap configurations.
Products: Johns Manville Product Specs
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