The barrier consists of graphite-impregnated cloth, covered with a reinforced Kraft paper and sealed. The graphite-impregnated side faces downwards and outwards on the sides folded up the joists and this expands in a fire, sealing any void between the barrier and the joists.
Metal fixing plates 30mm x 50mm with a hole drilled in the middle are used to fasten the barrier to the joists with 30mm galvanised clout nails (nails not supplied).
When ordering under-floor fire barrier, the width measurement required is the width between the joists plus 100mm, as there must be a 50mm fold of the barrier fitted to the joist on each side. For example, if width between joists was 400mm, then you would need to order a barrier with 500mm width.
The under floor fire barrier is layed on top of the ceiling. Allow for a 50mm up each side of joist (e.g. if the gap between the joists is 400mm, a 500mm wide under floor barrier is required). 12 long fixing washers are supplied for fixing every 300mm apart per barrier. Individual sections of the barrier should be overlapped by 50mm.
For acoustic requirement to U value and to meet Document E (H in Scotland) a 40mm thick sponge is supplied for the width between the joists – simply push into place between joists once the barrier is fitted.