There are three common materials used to insulate the cavity walls of a house.

Blow Mineral Fibre

The first material is blow mineral fibre. Like loft insulation, the fibre consists of fibreglass or mineral wool that is pushed into the wall cavity using compressed air. There are no restrictions on this material so it can be used nationwide and is covered by BBA (British Board of Agreement) certificates.

Beads or Granules

The second type of cavity wall insulation material is polystyrene beads or granules. The beads can be installed either lose of moulded together with light sticky resin to keep them together. Polystyrene granules will stick together because of their rough shape so don’t need to be held together with resin. Like the mineral fibres, the polystyrene is blown into the cavity using compressed air and both beads and granules are covered by BAA certificates.

Foam

The final material used is a foam insulant. The foam, urea formaldehyde, is created within the wall cavity by injecting a mixture of two chemical components. The foam expands in the cavity as the two components continue to mix, filling the gap. This type of insulation is covered by British Standards BS:5618 for the material and BS5617U for the application.

Don’t worry too much about which of the three materials you want to use – your installer will know the most suitable type for your home. But do ask the installer if they’re using Energy Saving Recommended insulation as it complies with British standards and has a 25-year guarantee.