About a third of all the heat lost in uninsulated properties escapes through the walls

By properly insulating cavity walls, you can guarantee you will save energy and cut costs off your heating bill.

As a rule, houses built from the 1990s onwards generally had wall insulation to keep the heat in, but if your house is older than that, it may not have any wall insulation at all.

Houses in the UK mostly are built with either solid walls or cavity walls:

After 1920’s

If your house was built after the 1920s, it is likely to have cavity walls. A cavity wall is made up of two walls with a gap in between, known as the cavity; the outer leaf is usually made of brick, and the inner layer of brick or concrete block.

Pre 1920’s

If your house was built pre-1920, it is more likely to have solid walls. A solid wall has no cavity; each wall is just a single block solid wall, usually made of brick or stone.

Working out your wall type

We can call out and see what walls you have so then can rule it if you have any cavity wall insulation.

If you want to check yourself and you can see your brickwork on the outside of the house, look at the pattern of the bricks because this can show how the wall has been built.

Cavity Wall

If your home has cavity walls, the bricks will usually have an even pattern with all the bricks laid lengthways.

Solid Wall

If your home has solid walls, the bricks will have an alternating pattern, with some bricks laid across the wall so you can see the smaller ends from the outside.

If the brickwork has been covered by some cladding or rendering, you can still tell by measuring the width of the wall. You can do this by looking at a window or door on one of your external walls.

If a brick wall is more than 260mm thick then it probably has a cavity a narrower wall is probably solid. Stone walls may be a bit thicker still but are usually solid, for example an old cottage made on limestone.

Some houses have a different type of wall structure altogether. If your house is a steel-frame or timber-framed building, or is made from pre-fabricated concrete, then you will need to ask us to advise first.

Cavity wall insulation explained

Many cavity walls can be insulated by injecting insulation material into the cavity from the outside.

We generally will drill holes in the outside walls, inject insulation through the holes and then seal them with cement. The insulation material is usually either mineral wool or polystyrene beads, but polyurethane foam may sometimes be used instead.

To insulate your cavity walls, we will drills small holes around 22mm in size at intervals of around 1m in the outside wall of your home. We then will blow insulation into the cavity using our special equipment. Once all the insulation is in, we will fill in the holes in the brickwork so you barely notice them.

Costs and Savings

Typical installation costs of cavity wall insulation vary depending on the size of your home. But whether you live in a large detached house or small flat, you should be able to make back the installation cost in less than five years through cheaper energy bills.

If you qualify for our grant this will cost you nothing.


Is your home suitable for cavity wall insulation?

You can check if your your home will be suitable for standard cavity wall insulation if it meets the following criteria:

  • Firstly our highly qualified surveyors will visit your home for free at a time and date to suit you

  • Throughout the process you will have just one point of contact
  • Our team of surveyors will advise what grants funded by the Government ECO scheme and Local Authorities you are eligible for
  • They will also recommend energy saving measures that are available to you and your property
  • Maximum waiting time is 10 days

You will then need us to carry out a survey. If it qualifies, we will then be able to insulate your walls using mineral wool, or polystyrene beads.


Most modern homes are generally constructed of two masonry walls (brick or block), with at least a 50mm airgap or ‘cavity’ in between them.

Most people are aware of what loft insulation looks like. It is generally a mineral wool made out of either glass or rock fibres and is packaged into a roll. This is laid out like a quilt into the loft space. Cavity wall insulation is a similar product, made in the same manufacturing plants, within the UK, as loft insulation, but is specially treated with silicants and milled down in order for it to be blown into the cavity of your home. It therefore creates the same quilt-like effect as loft insulation but in the enclosed void around your home.

Our technicians will arrive at your home and perform a pre-installation check. Remember to ask them for their identification cards.

The installation process is essentially in two parts. Firstly, the technician will drill holes in the mortar in-between the bricks of your home, at specific points around each elevation. These holes will be of 22mm to 25mm in diameter.

The insulation will then be injected into the holes from the outside (via the machine in the van) taking between two to three hours (for a three bedroom semi detached house).

The drilling process does create some vibration – so it would be wise to remove ornaments, particularly on external walls, for safety and peace of mind.

The technician will need to gain access to all walls, so he will need to get inside attached garages, lean-to-sheds, conservatories etc. If you have a wall right on a boundary, you may like to mention to your neighbour that the technician will need to go onto their property.

The technician must undertake checks before and after installation, including any heating appliances, so it is essential that they have access inside the property.

The drilling process inevitably creates a little dust. The technician will go around the outside of your home at the end of the installation and clean up. It is important to note however, the conditions and nature of our weather can at times hamper even the most determined attempts.

Please, take the time to speak with our staff and be sure that you are happy with the finished product.

We also believe it wise to remove vehicles from the drive and items close to the walls. In return this will give the technician better access for equipment and tools.

We also believe it wise to remove vehicles from the drive and items close to the walls. In return this will give the technician better access for equipment and tools.

This is usually a length of bristle brush. If the neighbour’s house were to be insulated at the same time, or has already been insulated, the cavity barrier will not be needed.

This system of cavity wall insulation has a defined pattern of holes, which has been tested by the British Board of Agrément to verify that it results in a complete fill.

Also, during your survey, we took measurements of your home including a depth gauge and inspection of the cavity to be filled. From these measurements we know the amount of material required to correctly fill your walls.

The technician will, therefore, check and record this data and match this against the quantity of insulation used. Our internal office staff operate a 100% check of this data and measure your results before we issue your 25 year guarantee.

It is possible that you may also be randomly selected in our on-site technical monitoring.

Ventilators supplying combustion air to fuel burning appliances must be safeguarded. Similarly ventilators at ground level that ventilate below timber floors must be safeguarded.

The technician will investigate them to check they are already sleeved. If they are not, the technician will remove them and seal around them to stop them being blocked by the insulation. Other vents, which may be redundant, such as cavity vents or vents that are in bedrooms may be closed off.

The technician should discuss these with you, so if you have any questions please ask.

Redundant airbricks may be filled.

The technician will fill all the injection holes with mortar that closely matches the existing colour and texture.

On some older properties or weathered facades it may take several months for the newness of the mortar to blend, but these holes are very small and they will blend as the weather effects them.

On pebbledash finishes, they will apply pebbles to the surface to match the existing finish, as close as possible.

Normally, we will not paint the injection holes. Unfortunately, even if the original paint is used, it may not match due to weathering. So it may be necessary for you to consider painting the area, after the mortar has dried.

The guarantee you will receive is called a “CIGA” (Cavity Insulation Guarantee Agency) which guarantees workmanship and materials for 25 years.

We will apply for it on your behalf and it will be sent to you direct from CIGA. It can take up to 8 weeks for this to be delivered to you after installation.

Insulation dramatically reduces heat loss through the insulated wall therefore you will be able to achieve the same temperature in your home by turning your thermostat down by a little.

Your property should still achieve the desired warmth because the house will retain its temperature for longer.

It can also be noted that during the summer the insulated cavity will prevent some of the suns heat from entering the walls, therefore, keeping your home cooler.

No, not to the cavity wall insulation, but normal building maintenance is needed..

Talk to us to discuss your concerns and allow us an opportunity to investigate your worries. Most concerns can be resolved swiftly and efficiently so please do not hesitate to speak to a member of our customer services team.

For the life of the building – the British Board of Agrément say so.

Talk to us to discuss your concerns and allow us an opportunity to investigate your worries. Most concerns can be resolved swiftly and efficiently so please do not hesitate to speak to a member of our customer services team.

Yes, Grant Funding is available (subject to application conditions). Click here to apply.