"Description of Roof Membrane System" and in the
absence of rigid board roof insulation. Include
mechanical attachment or top mop requirements as
applicable. Where rigid board roof insulation is a
component of the roof system, ventilating base
sheets should be specified in the roof insulation
section 07220.
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Apply ventilating base sheets with 75 mm (3 inch) side laps and 150 mm (6
inch) end laps in accordance with manufacturer's printed application
instructions for substrate [and wind uplift conditions ]specified.
[Mechanical attachments shall be as required for wind resistance specified
and to include increased frequency of attachment at corner and perimeter
areas. Drive fasteners flush with no dishing or cupping of fastener
plate.] [Top mop perforated sheet with a full, continuous mopping of hot
asphalt.]
]3.3.5
[Fiberglass Felt][Modified Bitumen] Base Sheet
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NOTE: Select the applicable application method.
Delete other options. Delete requirements for
adhered base sheets where the sheet is to be
mechanically fastened through to nailable deck.
Apply base sheets at right angles to roof slope,
except on insulated roofs where nailers (insulation
stops) have been applied at right angles to slope
and on decks sloped one inch per foot or more, apply
felts parallel to roof slope. Include requirements
for applying felts to barrel-type roofs only when
applicable.
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[Fully adhere [spot adhere] base sheets in accordance with membrane
manufacturer's printed instructions. [Spot adhesion shall be with hot
asphalt applied in 300 mm (12 inch) diameter spots installed in two
staggered rows, centered 300 mm (12 inches) in from edge of the base
sheet.][Apply cold adhesive with airless sprayer or a 6 mm (1/4-inch)
saw-toothed rubber squeegee and at application rate recommended by the
membrane manufacturer. Fully cover substrate with cold adhesive. Ensure
laps areas of base sheet are fully sealed.] Roll and broom in the base
sheet to ensure full contract with the [hot asphalt][adhesive]
application.] [On nailable substrates, mechanically fasten base sheet in
conformance with specified wind resistance requirements and membrane
manufacturer's printed instructions, and to include increased fastening
frequency in corner and perimeter areas. Drive fasteners flush with no
dishing or cupping of fastener plate. Where applicable, base sheet may be
mechanically fastened in conjunction with insulation to the substrate, in
accordance with membrane manufacturers printed instructions.] Apply sheets
in a continuous operation. Apply sheets with side laps at a minimum of 50
mm (2 inches) unless greater side lap is recommended by the manufacturer's
standard written application instructions. Provide end laps of not less
than 150 mm (6 inches) and staggered a minimum of 1 meter (36 inches).
Apply sheets [at right angles to the roof slope so that the direction of
water flow is over and not against the laps] [parallel to the roof slope]
[so that plies of sheets extend from eave line on one side of the
barrel-type roof and 450 mm (18 inches) over the center line of the crown
of the roof. Apply sheets on the other side in the same manner, resulting
SECTION 07550
Page 29
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