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Reroofing |
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Spud Surface (SP) Using a manual or mechanical method, remove all the gravel from the surface of the existing roof system. After removal of
the gravel, the existing membrane surface must be flat and smooth with no remaining gravel or debris. Wet or damaged areas of existing
membrane must be removed and replaced with new, dry materials compatible with the new roofing system. The existing membrane should
then be randomly cut with an axe or other device at an approximate rate of one 6" (152 mm) cut per 10 square feet (0.92 m2). Proceed with the
installation of an approved New System Base followed by an approved JM roofing system specification.
1. Mechanically Attach Existing Insulation. All wet and damaged insulation boards must be completely removed and replaced with an
approved insulation that is compatible with the new roofing system. Use an approved, corrosion-resistant fastener of sufficient length to
penetrate through the existing insulation and into the structural deck. If fastening to a metal deck, the fasteners must be of sufficient length to
penetrate the decking at the bottom of the rib opening.
2. Mechanically Attach New Insulation. Apply the units of approved JM roof insulation with long joints continuous. End joints should be
staggered so that they are offset at least 12" (305 mm) from the end joints in adjacent rows. If the new insulation is being installed over an
existing layer of insulation, all joints in the insulation layers must be offset a minimum of 6" (152 mm) between layers. Use an approved
mechanical fastener of sufficient length to penetrate through or into the deck, as required for the specific fastener. If fastening to a metal deck,
the fasteners must be of sufficient length to penetrate the decking at the bottom of the rib opening. Fasteners should be placed in the pattern
for the FM approval desired but never closer than 6" (152 mm) from any edge of the insulation board. Fasteners are to be driven through the
appropriate insulation plates. Care should be taken not to overdrive or under-drive the fastener. Overdriving the fastener will cause the
insulation plate to "cup" and can result in inadequate performance and damage to the membrane. Underdriving can cause the insulation to be
loose from the deck and allow the fastener to penetrate into the membrane.
Apply only as much insulation as can be covered by a complete roof membrane in the same day. Do not leave insulation exposed to the
weather.
If a vapor retarder is to be used with this construction, it should be placed on top of a minimal base layer of mechanically attached insulation.
The bulk of the thermal roof insulation should be placed on top of the vapor retarder. Refer to the "Vapor Retarders" section of the JM
Commercial/Industrial Roofing Systems Manual for more information.
3. Spot Mop New Insulation. For spot mopping, set the approved JM insulation board into spot moppings of hot asphalt (within 25°F [14°C]
of the EVT). The spot moppings shall be applied by machine at the rate of approximately 7 lbs. per square (0.34 kg/m2). Porous substrates
may require greater amounts of asphalt. The spots shall be approximately 12" (305 mm) in diameter and 24" (610 mm) on center. Adjacent
rows shall be staggered. Apply only as much insulation as can be completely covered with a finished roof membrane in the same day. Do not
leave insulation exposed to the weather.
4. Solid Mop New Insulation. Firmly set the units of approved JM roof insulation, long joints continuous and short joints staggered, into a full
mopping of hot asphalt (within 25°F [14°C] of the EVT). The asphalt should be applied at an nominal rate of 30 lbs. per square (1.46 kg/m2).
Porous substrates may require greater amounts of asphalt. When adhering insulation with hot asphalt, board size must be no greater than 4'
by 4' (1.22 m x 1.22 m). If insulation is being installed over an existing layer of insulation or in multiple layers, all joints must be offset a
minimum of 6" (152 mm) between layers.
Apply only as much insulation as can be covered by a complete roof membrane in the same day. Do not leave insulation exposed to the
weather.
5. Mechanically Attach New Base Sheet. Using an approved JM base sheet, start with a 12" (305 mm) width (the use of a specific base
sheet may be a condition of Guarantee). The subsequent base sheet courses are to be applied full width, lapping the preceding felt 2" (51
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. For additional fastener information, refer to the Fastener
Data in the "Roof Decks" section of the current JM Commercial/Industrial Roofing Systems Manual.
6. Spot Mop New Base Sheet. Using an approved JM base sheet, start with a 12" (305 mm) width (the use of a specific base sheet may be
a condition of Guarantee). The following base sheet courses should be applied full width, lapping the side laps 2" (51 mm) and the end laps 4"
(102 mm) over the preceding felts. Set each felt firmly into spot moppings of hot asphalt (within 25°F [14°C] of the EVT). The spot moppings
should be applied by machine at the rate of approximately 7 lbs. per square (0.34 kg/m2). The spots should be approximately 12" (305 mm) in
diameter and 24" (610 mm) o.c. Adjacent rows should be staggered.
3. Spot Mop New Insulation. For spot mopping, set the approved JM insulation board into spot moppings of hot asphalt (within 25°F [14°C]
of the EVT). The spot moppings shall be applied by machine at the rate of approximately 7 lbs. per square (0.34 kg/m2). Porous substrates
may require greater amounts of asphalt. The spots shall be approximately 12" (305 mm) in diameter and 24" (610 mm) on center. Adjacent
rows shall be staggered. Apply only as much insulation as can be completely covered with a finished roof membrane in the same day. Do not
leave insulation exposed to the weather.
4. Solid Mop New Insulation. Firmly set the units of approved JM roof insulation, long joints continuous and short joints staggered, into a full
mopping of hot asphalt (within 25°F [14°C] of the EVT). The asphalt should be applied at an nominal rate of 30 lbs. per square (1.46 kg/m2).
Porous substrates may require greater amounts of asphalt. When adhering insulation with hot asphalt, board size must be no greater than 4'
by 4' (1.22 m x 1.22 m). If insulation is being installed over an existing layer of insulation or in multiple layers, all joints must be offset a
minimum of 6" (152 mm) between layers.
Apply only as much insulation as can be covered by a complete roof membrane in the same day. Do not leave insulation exposed to the
weather.
5. Mechanically Attach New Base Sheet. Using an approved JM base sheet, start with a 12" (305 mm) width (the use of a specific base
sheet may be a condition of Guarantee). The subsequent base sheet courses are to be applied full width, lapping the preceding felt 2" (51
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. For additional fastener information, refer to the Fastener
Data in the "Roof Decks" section of the current JM Commercial/Industrial Roofing Systems Manual.
6. Spot Mop New Base Sheet. Using an approved JM base sheet, start with a 12" (305 mm) width (the use of a specific base sheet may be
a condition of Guarantee). The following base sheet courses should be applied full width, lapping the side laps 2" (51 mm) and the end laps 4"
(102 mm) over the preceding felts. Set each felt firmly into spot moppings of hot asphalt (within 25°F [14°C] of the EVT). The spot moppings
should be applied by machine at the rate of approximately 7 lbs. per square (0.34 kg/m2). The spots should be approximately 12" (305 mm) in
diameter and 24" (610 mm) o.c. Adjacent rows should be staggered.
