]3.4.4
Special Precautions for Installation of Foam Insulation
3.4.4.1
Polyisocyanurate Insulation
Where polyisocyanurate foam board insulation is provided, install 13 mm 1/2
inch thick wood fiberboard, glass mat gypsum roof board, or 19 mm 3/4 inch
thick expanded perlite board insulation over top surface of foam board
insulation. Stagger joints of insulation with respect to foam board
insulation below.
[3.4.4.2
Polystyrene Insulation
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NOTE: Include these requirements when polystyrene
insulation is used under fully-adhered EPDM, CPE,
PIB, or PVC roofing.
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a.
Over top surface of non-composite polystyrene board, install 13 mm
1/2 inch thick high density wood fiberboard, 19 mm 3/4 inch thick
expanded perlite board, glass mat gypsum roof board, or other
overlayment approved by roofing sheet manufacturer. Tightly butt
and stagger joints of field applied overlayment board at least 150
mm 6 inches with respect to the polystyrene board below. Apply
150 mm 6 inch wide glass fiber roofing tape centered over joints
and edges of overlayment board.
b.
Where composite boards consisting of polystyrene insulation are
provided, apply 150 mm 6 inch wide glass-fiber roofing tape
centered over joints and edges of composite board. Apply joint
strips as recommended by roofing sheet manufacturer.
]3.4.5
Cant Strips
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NOTE: Generally cant strips are not required for
single ply roofing systems. However, if cant strips
are necessary, coordinate location with mechanical
drawings to ensure that no projections, such as vent
pipes and braces, will be constructed through or
within 250 mm 10 inches of cant strips. Specify
wood cants, edge strips, and pressure preservative
treatment in Section 06100NA. Delete reference to
asphalt application unless asphalt is used in
applying the insulation.
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Where indicated, provide cant strips at intersections of roof with walls,
parapets, and curbs extending above roof. Wood cant strips shall bear on
and be anchored to wood blocking. Fit cant strips flush against vertical
surfaces. Where possible, nail cant strips to adjoining surfaces. Where
cant strips are installed against non-nailable materials, install in [heavy
mopping of asphalt or set in a heavy coating of asphalt roof cement] [an
approved adhesive].
3.4.6
Tapered Edge Strips
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NOTE: Delete reference to asphalt application
SECTION 07220
Page 24
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