Three main types of cavity wall insulation are commonly used in the UK:

Mineral wool insulation:

This is the most common type of cavity wall insulation and is made from glass or rock wool fibres. Mineral wool insulation is generally considered to be a good all-around insulator, as it is affordable, easy to install, and has good thermal properties. It is also non-combustible and resistant to moisture, which helps to prevent dampness and mould from developing in the walls.

Foam insulation:

This type of insulation is made from a polyurethane foam that is injected into the cavity using specialized equipment. Foam insulation is more expensive than mineral wool insulation but offers better thermal performance, as it has a higher R-value per inch of thickness. It is also more resistant to moisture and can help to reduce the risk of condensation forming on the walls.

Bead insulation:

Bead insulation for cavity walls is a type of cavity wall insulation that involves injecting small beads of insulating material into the cavity between the two layers of external walls of a building. The beads used in cavity wall insulation are typically made of expanded polystyrene (EPS) or polyurethane foam.

The process of installing bead insulation involves drilling small holes into the external walls of the building, usually at regular intervals of around 1 meter, and then using a specialized injection tool to blow the beads into the cavity under pressure. The beads then settle and interlock with each other, creating a continuous layer of insulation that fills the cavity.

Bead insulation can be a cost-effective way to improve the energy efficiency of a building, as it is relatively inexpensive and quick to install. It can also help to reduce heat loss through the walls, which can lead to lower energy bills and a more comfortable living environment. However, any type of cavity wall insulation is not suitable for all properties, and a professional assessment by someone like me should be carried out to determine whether it is appropriate for your home. Additionally, proper installation is important to ensure that the insulation is effective and does not cause any problems with dampness or mould. Different parts of the UK and its weather is also an important consideration.

Before insulating a cavity wall

It is important to carry out a few checks to ensure that the property is suitable for cavity wall insulation and that the insulation will be effective. Here are some of the key things to check:

Cavity wall suitability:

Not all properties are suitable for cavity wall insulation. Homes built before the 1920s generally do not have a cavity, and some properties may have existing insulation that needs to be removed before new insulation can be installed. A professional assessment should be carried out to determine whether your home is suitable for cavity wall insulation.

Wall condition:

The external walls of the property should be in good condition, with no signs of dampness or other damage. If there are any issues with the walls, such as cracks or holes, these should be repaired before installing insulation. The cavity itself also needs to be clear of obstructions such as building matrials or objects that could bridge the cavity. It is also important that the wall has a suitable DPC at its base.

Ventilation:

Cavity wall insulation can reduce ventilation in the walls, which can lead to dampness and mold if not properly managed. It is important to ensure that there is adequate ventilation in the property, either through the installation of passive air vents or by ensuring that existing vents are not blocked. The general ventilation within the property should also be considered to promote a healthy, happy home.

Building regulations:

Any new cavity wall insulation installation must comply with current building regulations. This may include requirements for fire safety, ventilation, and energy efficiency.

Installer accreditation:

It is important to choose a reputable installer who is accredited by a recognized industry body, such as TrustMark, the National Insulation Association (NIA) or the Cavity Insulation Guarantee Agency (CIGA).

By checking these key factors before insulating a cavity wall, you can help to ensure that the insulation is effective, safe, and will not cause any problems in the future.