Application - Loft floor / above ceiling / below ceiling
including between and above + between joists, and below ceiling
Insulating at ceiling or loft floor level generally occurs in a cold roof environment, in which case the most common, best value, and easiest to install standard solution is to uses a Glass Mineral Wool Loft Roll.
In cases where noise is a problem, Acoustic Partition Roll is favoured, as it provides both thermal and acoustic insulation properties.
Complications arise when occasional use is made of the loft for storage, for example. In this case partial or complete boarding of the floor of the roof void is desired. One way to resolve this all-to-common problem is to use mineral wool slabs between the ceiling joists, then fit battens perpendicular to the joists, and insulate between these battens and applying chipboard flooring on top.
Insulation Installation Locations
Cold roof joist level applications include insulation ...
Between Ceiling Joists -
It is almost certain that insulating between the joists alone will not be sufficient, as a depth of 300mm of Loft Roll 44, is the recommended minimum to achieve a U Value of 0.18, as required by building control.
It should be understood that the flossy formation of loft roll must be maintained to ensure its effectiveness. Squashing the air out of loft roll will dramatically reduce its thermal value.
Between and Above Joists -
The most common build-up of Loft Roll insulation is fit 100mm between the joists then placing 200mm (or 2 x 100mm) above the rafters perpendicular to each other.
Soundproofing can be enhanced by fitting Mineral wool slabs in place of, or in conjunction with Loft Roll or Acoustic Partition Roll.
Reflective foils and rigid insulation with solid aluminium facings are not recommended in this location, due to their potential to promote condensation.
Mechanically fixed insulated plasterboard is recommended when other alternatives do not exist.