When thermal blocks are shown, a maximum of 50 mm (2
inches) of batt insulation may be compressed at
purlins.
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Insulation shall be continuous over entire roof surface. Where expansion
joints, terminations, and other connections are made, the cavity shall be
filled with batt insulation with vapor retarder providing equivalent
R-value and perm rating as remaining insulation. Insulation shall be
installed as indicated and in accordance with manufacturer's instructions.
3.2.1
Board Insulation with Blanket Insulation
Rigid or semirigid board insulation shall be laid in close contact. Board
shall be attached to the metal roof deck with bearing plates and fasteners,
as recommended by the insulation manufacturer, so that the insulation
joints are held tight against each other, and shall have a minimum of 1
fastener per 0.37 square meters 1 fastener per 4 square feet. Layout and
joint pattern of insulation and fasteners shall be indicated on the shop
drawings. If more than one layer of insulation is required, joints in the
second layer shall be offset from joints in the first layer. A layer of
blanket insulation shall be placed over the rigid or semirigid board
insulation to be compressed against the underside of the metal roofing to
reduce thermal bridging, dampen noise, and prevent roofing flutter. This
layer of blanket insulation shall be compressed a minimum of 50 percent.
3.2.2
Blanket Insulation
Blanket insulation shall be installed between and parallel to the purlins
with tabs of a facer lapping on the top face of the purlins. Thermal
blocks shall be provided over purlins, between clips. A second layer of
unfaced insulation shall be added between purlins to provide full R-value.
Blanket insulation shall be supported by an integral facing or other
commercially available support system.
3.3
PROTECTION OF VAPOR RETARDER FROM ROOF DECK
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NOTE: Delete this paragraph if the vapor retarder
will not be in direct contact with the roof deck.
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A cloth industrial duct tape shall be applied over the seams of metal roof
decks, at penetration edges, and at surface areas exhibiting sharp burrs or
similar protrusions. For other types of roof decks, cloth industrial duct
tape shall be applied over irregularities which could potentially puncture
polyethylene membrane.
3.4
VAPOR RETARDER INSTALLATION
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NOTE: Choose one paragraph and delete the other.
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3.4.1
Integral Facing on Blanket Insulation
Integral facing on blanket insulation shall have the facing lapped and
sealed with a compatible tape to provide a vapor tight membrane.
SECTION 07416A
Page 27
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