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APP Modified Bitumen Specifications |
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Specification 2CIN-W/2PIN-W |
Two Ply Heat
Welded Modified Bitumen Mineral Surfaced Roofing System. For use over Johns Manville (JM)
insulation, approved decks, 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
which is not
nailable and which provides a suitable surface to receive the roof. Poured and pre-cast
concrete decks require priming with JM Concrete Primer prior to application of the first
heat welded modified bitumen ply. This specification is not to be used over poured or
pre-cast gypsum decks, lightweight insulating concrete decks or fills without JM
insulation.
This specification is also for use 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. 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. For
heat weld applications directly to the insulation, the top layer of insulation must be JM Nord Board.
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
Heat weld a 19 3
/4" (502 mm) wide piece of one of the base plies listed. The
remaining plies are to be applied full width, with 4" (102 mm) side and 6" (152
mm) end laps over the preceding sheets.

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.
For an identical copy of this specification,
ask for RS-4353.