Cavity Wall Insulation

What are the benefits?

A massive benefit of cavity wall insulation is that your property will be warmer in winter and cooler in the summer, saving energy resulting in lower fuel costs.

If your property qualifies, you can get this insulation for free.

If your property was built after 1930, it is probably made of cavity wall construction. Cavity walls are made of two brick or block layers with a small gap or ‘cavity’ between them to provide an insulating layer of air.  Up to 35% of all heat loss in your property is lost or leaked through the walls.

A good way to illustrate this is in terms of heat retention. The rate at which heat escapes through the surface is called the uValue. The higher this number, the faster the heat escapes.

A typical un-insulated
cavity wall uValue
A typical insulated
wall uValue
  1.6 0.46

This shows that heat retention is improved by more than 300%.

How does it work?

Cavity wall insulation is used to reduce heat loss through a wall by filling the air space with material that inhibits heat transfer. This immobilises the air within the cavity (air is still the actual insulator), preventing convection, and can substantially reduce heating costs.

If your property is suitable for cavity wall installation our specialist team will drill small holes into the outside of the property. They will then use specialist equipment to inject insulating material into the cavity. We use material made from a high percentage recycled granulated mineral wool fibre or polystyrene carbon beads.

How much does it cost?

If your property qualifies under the ECO scheme then this insulation is absolutely free! If your building does not qualify, the cost is still affordable, and you will be able to make your money back on the savings on utility bills within three years. 

How much can I save?

As an example, a typical gas heated, three bedroom semi-detached property can expect to see the following savings:

Cost savingsEnvironmental savings
Up to £140 per year Up to 560kg of carbon dioxide.

*Source: Energy Saving Trust, 2013

What is the process?

We will ensure that there is minimal disruption to you or your tenants.

Process Step One

The first step in carrying out the work is to drill a pattern of holes through the outer leaf of the walls in the mortar line. Holes are generally of 22-25mm diameter and are ‘made good’ after injection.

Process Step Two

The pattern of drill holes varies between different insulation systems but the holes are typically around 1.35 meters apart and at set heights up the wall, starting below windowsill level and working up to the top of the wall. 

Process Step Three

The loose wool insulation or bead is blown into the cavity until it is tightly packed and no gaps are left.  A pressure sensor on the blowing machine cuts off the flow of material when the cavity is full. The process begins at the bottom of the wall. Mineral fibre is then back filled through the holes across the wall and the process continues in layers up the wall.

Process Step Four

All holes are filled with matching mortar to complete the work. In most cases the whole job can be complete in under half a day.


If you are interested in insulation and would like to find out what would be suitable for your property, please contact us today. We can operate over the entire UK with the majority of our focus being Hampshire, Berkshire, West Sussex, Dorset and surrounding counties.