Cavity Wall Insulation

It is good practice to insulate cavity walls because it saves heat loss from a house, but it is not a DIY job. To check if the cavities have already been filled, you can drill a hole into the cavity from the outside and feel with a probe. If it is empty, call in a contractor specialising in cavity insulation.

Since it is impossible to check how well the work has been done or how long the insulation will last, you have to rely on the contractor's integrity.

First, check that the walls show no sign of penetrating damp. Walls should not be filled while damp is present, so you must eliminate the cause of the damp and wait for the walls to dry out.

Cavity Wall Insulation
There are two main insulation systems to choose between, with similar installation methods. The dry system consists of mineral-wool fibres or expanded polystyrene beads being blown through holes drilled in the outer leaf of the wall until the cavity is filled.

With the second system, the cavities are filled with foam. This is produced on site and pumped through holes drilled in the outer leaf, The foam normally dries after a few days and. becomes firm. This system is not suitable for timber-framed houses.