Page 74 - Glow Insulation Product Guide
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Flat Roof: Timber Deck insulated above joists Insulated with Quinn Therm Plydeck QRFR-PLY
Design and Installation
The foil facing on the underside of Quinn Therm QRFR-PLY has a very high vapour resistance and can be formed into an AVCL by sealing the joints between boards: set the boards onto a wide (30mm) bead of vapour resistant sealant applied to the upper surface of all the joists and cross noggins.
Quinn Therm QRFR-PLY should be fixed with low profile headed screws, long enough to give minimum 35mm embedment into the timbers. Fixings should be at 200mm centres around the board edges (300mm centres on any intermediate timbers) and set at least 10mm from board edges and 50mm from corners. Fixings for adjacent boards should be staggered to the same joist or noggin and screw heads must finish flush with the surface of the plywood.
To prevent water damage to Quinn Therm QRFR-PLY the waterproofing system should be installed as soon as possible. In poor weather Quinn Therm QRFR-PLY should be protected by polyethylene sheeting until the waterproofing system is installed.
Thermal bridging at roof-wall junctions must be avoided: at eaves and verges the joist space should be packed with insulation; at parapets vertical edge insulation should be applied to the inner face and the wall insulation carried at least 150mm above the surface of the Quinn Therm QRFR-PLY.
Access to flat roofs constructed with QRFR-PLY laminate should be for maintenance and repair only.
• Suitable for new build and refurbishment projects.
• Quinn Therm QRFR-PLY is a composite insulation board intended for forming warm flat roof decks which will be finished with partially bonded built-up felt waterproofing systems.
• The low thermal conductivity of the insulation minimises the board thickness, while the composite board offers rapid coverage and straightforward installation.
• Warm roof construction reduces the risk of condensation within the roof structure and eliminates the need for ventilation beneath the deck: it also protects the structure from extremes of temperature.

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