What is a cavity injection?

A cavity injection is a way of drastically reducing your heating bills by insulating the walls of your home. Cavity injection is a quick and inexpensive process that pays for itself in energy savings.

Cavity wall insulation can save you money

A cavity injection, also known as cavity wall insulation, is a simple way of making your home more energy efficient. Houses built after 1920 will usually need a cavity injection to fill the gap between internal and external walls, originally designed to prevent damp. A cavity injection will insulate your home and save money on your fuel bills, as well as cut your carbon footprint.

Cavity injections pay for themselves

A home that hasn’t been properly insulated loses approximately a third of its heat through the walls. Cavity injections insulate the walls of the house and reduce heat loss by up to 35 percent. As there is less heat loss, you use less energy keeping your home warm and therefore save money on your bills. This is how you make your money back from cavity injections; the reduction in the cost of your bills. If you are environmentally conscious you also have peace of mind that you’re using less of the earth’s resources to heat your home. Insulating, for example, a three bedroom semi-detached house would cost about £250. Cavity injections to insulate the home would save roughly £115 a year, so they are likely to pay for themselves in just over two years and then save you more money in the future.

Due to the environmental benefits of cavity injections, the government also offers substantial grants to help pay for cavity injections. You can apply for these grants online at the Energy Saving Trust website.

Materials used in cavity injections

Cavity injections usually involve the use of one of three materials, chosen for their insulating abilities which also maintain the indoor air quality of your home and are also fire resistant. The three materials commonly used are mineral wool, urea formaldehyde foam and expanded polystyrene beads.

Mineral wool is similar to materials used to insulate attics. It is made from fibreglass or rock wool and pumped into the cavity to insulate the building. Urea formaldehyde foam is similarly pumped into the cavity area. It then works into the cracks and seams of the cavity wall before drying. As it dries, air bubbles form in the material and help to trap heat in the home. The final material used is expanded polystyrene beads. These are mixed with an adhesive and pumped into the cavity area of the wall, creating air bubbles which insulate. All three materials must be manufactured according to British standards and foam insulation should be certified by the British Board of Agrément (BBA).

How do I get a cavity injection?

Cavity injections should be done by a qualified professional to ensure the best, certified materials are used and that the work is done to a high standard. Ask your installer if they are using Energy Saving Trust Recommended Insulation - it has a 25 year guarantee and complies with British standards.

JB