Johns Manville
3CBN-W/3PBN-W. CSI 3-Part Specifications.
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APP Modified Bitumen Specifications |
| Specification 3CBN-W/3PBN-W |
Three 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 |
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 26 1/4" (665 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 Commerical/Industrial Roofing Systems Manual.
Over the existing two plies, heat weld a full width piece of one of the cap