A Guide to Cavity Wall Insulation (CWI)
Cavity wall insulation (CWI) can be used in homes with cavity walls (the external walls of the house have a gap between two leaves of brickwork). It means you lose less heat through your walls.
Main benefits
- Reduces heat loss through the walls of your home, meaning that your heating system can be smaller and cheaper to run.
- Minimal disruption to install.
- Will retain the ‘thermal mass’ of the building, reducing the effect of temperature changes throughout the day, and so maintaining a more comfortable temperature in your home.
- Lower bills typically offset the cost of installing CWI within approximately 5 years.
Things to consider
- A borehole survey should be completed before filling cavity walls to ensure suitability.
- The materials used for CWI should be chosen based on the depth of the cavity and the location of the building, avoiding fibrous materials that can absorb moisture and slump over time, thereby reducing the insulating qualities of the wall.
