The best way to cut household heating bills is to reduce the amount of heat being lost, especially through the roof and walls. Loft insulation is a relatively straightforward DIY project but cavity wall insulation (CWI) must be left to the "experts".

Before you commit yourself though, be aware that, for a number of reasons, not all properties with cavity walls are suitable for insulation. In addition, some of the organisations promoting retro-fill CWI are driven by government targets and commercial interests. Their judgement may be influenced by these considerations.

The following are the main considerations to be taken into account.

• Ensure there that are no pre-existing problems with dampness in either the internal or external walls

• Explore the possibility of a grant through the Energy Saving Trust (

• Get a qualified surveyor to do a pre-assessment to verify that:

◦ the walls are sound with particular regard to brickwork, pointing and rendering (if present)

◦ the walls are not exposed to such severe weather as to rule out CWI, a potential problem in NW England

◦ the cavities are at least 50 mm wide, parallel-sided and unobstructed by debris, mortar on wall ties, electric cables &c.

◦ there is a high possibility of a successful outcome

•  Select an approved installer. The Energy Saving Trust has a list of Trade Bodies to which installers should belong

• Get a 25 year guarantee through the Cavity Insulation Guarantee Agency Ltd (

• Look forward to reduced heating bills and a warmer house!