a) Building Insulation Blanket (BIB) and Foil Faced BIB (FFBIB)
Roofing – Building Insulation Blanket (BIB) and Foil Faced BIB (FFBIB) are designed for use under any roof system which requires control of temperature loss or gain. FFBIB is a true vapour barrier which may be necessary for conditioned spaces. In these cases the lap may be sealed during installation. This may be accomplished using contact adhesive or a tape. A more practical solution for FFBIB is suggested using sealant/mastic. Wherever visible the foil reflects light creating a brighter environment below. Roofing underlay should always be placed on top of BIB, to avoid condensation from the roof underside wetting the BIB.
Where insulation is required to achieve its full R value it must not be laid over the purlins. Insulation must be laid between packers fixed onto the top of steel purlins with a 25mm air gap between roof and insulation. If this is not followed and the insulation is fixed over the top of the purlins and squashed down, the R value will be reduced. There is also a risk the roof will appear bumpy between fixings and the side laps will not fully fit together.
Wall – FFBIB is installed next to the external cladding (building paper should be placed between the cladding and the insulation) with the foil facing inward, the foil facing will reflect the light where it is visible.
Install the insulation system in a DRY state.
Butt adjacent edges of insulation tightly together and fill all gaps with offcuts to avoid heat leakage.
Fit insulation tightly around all roof penetrations and vent pipes except hot flues where a 150mm gap is required.
Where cutting is necessary use a sharp knife and a straight edge.
Where practical it is considered good practice to incorporate an air gap, for ventilation, between the insulation and the metal deck.
b) Sisalisation Foil, Fire Retardant Foil and White Faced Foil
Roofing – Lay foil horizontally on netting. White faced foil is laid with the white surface facing down. Start at the gutter line and lap successive layers by 150mm minimum. For an effective vapour barrier seal all openings and laps with an appropriate 48mm adhesive foil tape, such as 3M 425 foil tape 48mm wide.
For vertical application lay the foil in the ridge to gutter direction with all laps a minimum of 150mm and sealed with an appropriate 48mm adhesive foil tape, such as 3M 425 foil tape 48mm wide.
Walls – Ensure foil is fixed to the supporting framing with a fastener system that is durable for at least 15 years. Lay and tape the laps as for roofing.
For further information visit www.pinkbatts.co.nz
