Cavity Wall Insulation (CWI)

What is cavity wall insulation?

At Eco-Green Deals we have specially trained surveyors to identify your property and its requirements. Our engineers carry out an initial survey thus enabling us to discuss your property needs.

Given our experience and expertise of cavity insulation we can guide you from an initial survey right though till the installation of your cavity.

Our cavity wall insulation projects come with a 25 year guarantee which is administrated by CIGA thus providing you the peace of mind you most deserve.

CWI fills that gap, keeping the warmth in to save energy.


If your home hasn’t been insulated or you are not sure please contact us and we will gladly assist you further, you will qualify for FREE Cavity Wall Insulation under the governments ECO Scheme.

Installation process

To insulate your cavity walls, our fully trained technicians drills small holes around 22mm in size at intervals of around 1m in the outside wall of your home. With specially designed equipment, we then blow insulation into the cavity. Once all the insulation is in, we then fill the holes in the brickwork so you’ll barely notice them.

How much could I save each year?

This will depend on how old and inefficient your existing boiler is and the fuel your boiler uses. Below are some examples of potential savings for a home heated by gas central heating.

Upgrading an old gas boiler with a programmer and room thermostat, with a new A-rated condensing boiler with a programmer, room thermostat and thermostatic radiator controls (TRVs) could save you:

  • Fuel bill savings
  • Carbon dioxide savings
  • £150
  • 670 kg
  • £225
  • 1,120 kg
  • £95
  • 410 kg
  • £70
  • 310 kg

These are estimated figures based on insulating a gas-heated home. The average installed cost is unsubsidised. Figures are based on fuel prices as of April 2017.

Payback time

  • 5 Years or fewer
*SOURCE: Energy Saving Trust 2017

Frequently Asked Questions – External Cavity Wall Insulation

The external wall of a house is constructed of two masonry (brick or block) walls, with a cavity (gap) of at least 50mm between. Metal ties join the two walls together.

Cavity Wall Insulation normally takes around two/three hours to install, but the time does depend on the size of the house and other factors, such as access.

If you contact us we will carry out all the preliminary checks before an install can take place. We will undertake an assessment of your property to confirm that it is suitable for insulation.

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

The Technician will need access to all walls, so he will need to get inside attached garages, lean-to sheds, conservatories etc. The insulation can only be really effective if all walls are done. If you have a wall right on the boundary, you may like to mention to your neighbour, that the Technician will need to go onto their property

The drilling process inevitably creates a little dust, which will be cleared at the completion of the job. It may be wise to remove vehicles from the drive and things close to the walls. This will also give the Technician better access for equipment and tools.

Assuming your neighbour’s house is not already insulated, the Technician will insert a cavity barrier at the party wall line. This is usually a length of bristle brush. Of course, if the neighbour’s house were to be insulated at the same time, the cavity barrier would not be needed.

All Technicians undergo training by the system supplier and the installing firm to ensure they are competent in CWI and carry a training card. Please feel free to ask to see the training card.

The Technician will fill all the injection holes with mortar to match the existing brickwork as closely as possible. We will use a mix that closely matches the existing colour and texture. On pebbledash finishes, we will apply pebbles to the surface to match the existing finish. After weathering, the holes are difficult to see.

Normally, the installing firm 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.

No, we will submit the Guarantee application. The Guarantee is posted to you within days of the application being received at CIGA. – Keep it safe

CIGA is non-profit distributing; its only function, is to stand as guarantor for the promises set out in the Guarantee. It has the resources to meet the promises made in the Guarantee.

All professional approved installing firms are members of CIGA and can apply for a CIGA Guarantee, for properties built with traditional cavity walls. You should insist on a CIGA Guarantee, since nothing else can give you the level of assurance to which you are entitled.


With CWI, you should find that the house holds its temperature for longer, therefore the time between heating cycles may be longer. The result should be a more even temperature throughout the house as well as a reduced fuel bill.

No, not to the Cavity Wall Insulation, but normal building maintenance is needed.

Talk to us and tell us the nature of your concern. A contract exists between you and us, so you must give us the opportunity to investigate your worries.

We will help.


A set criteria has to be met under the Governments Energy Company Obligation (ECO) scheme the majority of our customers qualify. All you have to do is get in touch and we will take care of the rest.

Applying for Funding

Eco-Green Deals are currently filling cavities around the entire UK under the governments ECO obligation scheme. We would love to hear from you

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