DATA SHEET Building Paper 714 (BS 1521 - Class A1F) DESCRIPTION Foil faced vapour barrier. Building Paper 714 is a foil-faced waterproof building paper meeting the requirements of BS 1521 A1F. CONSTRUCTION Building Paper 714 is a foil-faced waterproof building paper, with two layers of kraft paper laminated together with bitumen, reinforced with glass fibre yarn, and faced with a pure aluminium foil. TECHNICAL Basis Weight (g/m2) Tensile Strength – along rolll – across roll Vapour Resistance 1. Dry Lining Vapour Barrier • Fix (as above) ensuring any damp penetration is removed before dry lining. FIXING / SITEWORK Store rolls vertically before use on a clean, dry surface protected from the weather. Material should not be unrolled if the temperature is below 5°C as the membrane may become brittle and crack. Building Paper 714 is fixed internally on the warm side of the insulated structure. It should be nailed or stapled to the inside face of the studwork or framing. Seal all laps with butyl double-sided tape or with a suitable waterproof building tape and repair any holes or service penetrations. Roll Specification Roll weight 2. Pitched Roof – Insulated • ix below insulation (as above) ensuring adequate ventilation is provided or F use Roofshield for non-ventilated roof 3. Flat Roof – Insulated • Fix (as above) but allow 150mm overlaps.