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7550 Guide Specifications:
Modified Bitumen/Cap Sheet Roof System
F. Vapor Retarder Application – Wood Deck
1. Install one ply of dry sheathing paper; lap edges 2 inches (51mm).
2. Install [GlasBase] [DynaBase] starting by first applying an 18" (457 mm) wide layer. The following felts are to be applied full
width, lapping the preceding felt 3" (76 mm) on the side laps and 4" (102 mm) on the end laps. Nail the side laps 9" (229 mm) o.c.
Down the longitudinal center of each felt, place two rows of nails spaced approximately 11" (279 mm) apart, with the nails
staggered on approximately 18" (457 mm) centers. Use nails or fasteners appropriate to the type of deck with 1" (25 mm)
minimum diameter caps.
3. Mop surface with hot asphalt and embed [two plies] [one ply] of roofing felt, meeting ASTM D 2178, Type [IV] [VI]; lap plies [19
inches (483 mm)], [2 inches (51mm)]. Apply asphalt at 23 lbs./square (1.12 kg/m2) nominal.
4. Extend vapor retarder under cant strips and blocking.
G. Vapor Retarder Application – Concrete Deck
1. Apply JM Concrete Primer at one gal/square (0.41 liters/m2) and allow to dry.
2. Mop surface with hot asphalt and embed two plies of roofing felt; lap plies 19 inches (483 mm); apply asphalt at 23 lbs./square
(1.12 kg/m2) nominal.
3. Extend vapor retarder under cant strips and blocking.
H. Vapor Retarder Application – Metal Deck
1. Apply first layer of insulation with approved mechanical fasteners at rate and pattern to meet FM requirements
2. Mop surface of insulation with hot asphalt and embed two plies of roofing felt; lap plies 19 inches (483 mm). Apply asphalt at a
nominal rate of 23 lbs./square (1.12 kg/m2).
3. Extend vapor retarder under cant strips and blocking.
I. Insulation Application
1. [Ensure vapor retarder is clean and dry.]
2. Mechanically fasten [first layer of] insulation in accordance with FM requirements. [Embed a second layer of insulation into
mopping of hot asphalt in accordance with insulation manufacturer’s instructions.] [Install second layer of insulation with joints
staggered from first layer.]
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3. Embed [one layer] [two layers] of insulation into mopping of hot asphalt in accordance with insulation manufacturer’s
instructions. [Install second layer of insulation in hot asphalt with joints staggered from first layer.]
4. Minimum Total Insulation Thickness: [[_____] inch ([_____] mm).] [As required to achieve an insulation ‘R’ value of [_____] .]
5. Install insulation boards with edges in moderate contact, without forcing. Cut insulation to fit neatly to perimeter blocking and
around penetrations through roof.
6. [Install tapered insulation boards] [Cut boards to slope] for a distance of [18] [24] [_____] inches ([457] [610] [_____] mm) back
from roof drains for positive drainage.
7. Apply no more insulation than can be sealed with membrane in same day.
J. Membrane Application
1. Install [GlasBase] [DynaBase] [Ventsulation Felt] starting by first applying an 18" (457 mm) wide layer. The following felts are to
be applied full width, lapping the preceding felt 3" (76 mm) on the side laps and 4" (102 mm) on the end laps. [Nail the side laps 9"
(229 mm) o.c. Down the longitudinal center of each felt, place two rows of nails spaced approximately 11" (279 mm) apart, with the
nails staggered on approximately 18" (457 mm) centers. Use nails or fasteners appropriate to the type of deck with 1" (25 mm)
minimum diameter caps.] [Install each felt so that it shall be firmly and uniformly set, without voids, into the hot asphalt (within 25
degrees F [14 degrees C] of the EVT) applied just before the felt at a nominal uniform rate of 23 lbs. per square (1.12 kg/m2) over
the entire surface.]
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