Free Cavity Wall Insulation Grants are still available throughout S.Wales, covering the full cost of installation.

Free Cavity Wall Insulation can be a complicated matter. In an effort to make it easier for you to find what you are looking for, we have broken the page down to a list of frequently asked questions. With bite size pieces which are easier to digest.

Cavity Wall Insulation Video

A picture paints a thousand words. Watch this 5 minute video, and you will become an expert of cavity wall insulation

Wanted to insulate the walls of my home. Found The green Deal Wales online. They gave me a lot of confidence when I spoke with them over the phone. They came and did a 2 hour survey of the walls which gave me more confidence in the company. They also got me a grant which covered the full cost of the work. Excellent company 10 out of 10.
G. Johnson – Cardiff. January 2020

Can I get free Cavity Wall Insulation?

Under the Cavity Wall Insulation Grant scheme in Wales, about 95% of the cases that qualify for the Grant will get free cavity wall insulation.

The free Cavity Wall Insulation Grant qualification was widened in October 2018, so many people who did not qualify for this Grant before then, may now qualify

There is also a new Flexible Cavity Wall Insulation Grant available which is based on where you live, and other factors, but it is not based on benefits.

We would of course be pleased to give a quote to those that do not qualify for a grant on either scheme.

Telephone: 0800 8 10 10 60 or 07960 799681

What Cavity Wall Insulation do we use?

Free cavity wall insulation in Wales

We always install “SuperBead” Polystyrene Beads and not “RockWool” (fibre).

Polystyrene Bead is a superior material for insulating Cavity Walls, but it is more expensive. “SuperBead” cavity wall insulation has been certified for the following.

Thermal properties — “SuperBead” cavity wall insulation has a declared thermal conductivity of 0.035.
Water resistance — “SuperBead” cavity wall insulation will resist the transfer of water across the cavity, so no damp caused.
Condensation — “SuperBead” cavity wall insulation will contribute to limiting the risk of condensation because the internal walls will be warmer.
Behaviour in relation to fire —  “SuperBead” cavity wall insulation does not prejudice the fire resistance properties of the wall.
Durability — “SuperBead” cavity wall insulation is durable, rot-proof and water resistant. It is sufficiently stable to remain effective as an insulation for the life of the building.

“SuperBead” cavity wall insulation is up to 20% more efficient than fibre insulation.

The free cavity wall insulation is blown into the cavity with an adhesive which “goes off” in about 20 minutes. There are about 30% fewer holes than using fibre, and the holes are smaller.

This leaves a “solid” blanket of polystyrene wrapped around your home, and reduces heat loss through the walls by about 70%.

The beads have been thoroughly tested and will not deteriorate over time. They are fully fire resistant, and have approval for use in even the most extreme of conditions.

As a part of the initial survey we also carry out a CAS (Cavity Assessment Survey). The suitability of your walls to be insulated will be assessed.

This is part of the much improved quality control measures found in the new free Cavity Wall Insulation Grant scheme.

Call us on 0800 8 10 10 60 or 07960 799681

How is Cavity Wall Insulation installed free of charge?


The Government have massive European targets to reduce Carbon Emissions, so they passed the buck.

They gave a Legal Obligation to the Gas and Electricity companies to reduce Carbon Emissions.

This is know as the Energy Company’s Obligation, ECO for short.

The system was simplified in April 2017, with energy assessments being no longer required.

Instead, the Government have “deemed” an amount of Carbon Emission savings for each type of property – terraced, semi-detached, detached, etc. It also takes into account the number of bedrooms and the fuel you use to heat your home.

The Carbon Emission saved by insulating a wall are then sold to one of the Gas and Electricity companies. That is how free cavity wall insulation is funded.

The amount of carbon emissions saved = the value of the grant.

We all pay an amount on our fuel bills towards this fund. So yes, we pay for it in the end, as usual.

Call us on 0800 8 10 10 60 or 07960 799681

Are my Cavity Walls suitable for insulating?

A cavity wall in Bristol

Houses built after 1925, are likely to have external walls made of two skins of brick. There would be a cavity between them. The two walls would be held together with wall ties.

Insulation for Cavity Walls fills that gap, keeping the warmth in – thus saving energy. It can also help reduce condensation inside the house if this is a problem on your external walls.

Your home will usually be suitable for free cavity wall insulation if:
·         the external walls have an unfilled cavity
·         your cavity is at least 50mm wide
·         the masonry or brickwork of your property is in reasonably good condition

But it is not as simple as that.

As a part of the initial survey we also carry out a Cavity Assessment Survey (CAS). This is a PAS2035 and OFGEM compliant survey, with an Independent Surveillance of the Assessment (ISA) by CIGA.

CIGA is the underwriter of the 25 year guarantee which comes with every cavity wall insulated.

The suitability of the walls to be insulated will be assessed by way of an extensive survey of the property.

This survey includes drilling a small test hole into the wall of each elevation. A borescope is inserted into each hole and the cavity is examined.

Photographs of the cavity are taken, along with measurements of the depth of the cavity.

All walls are carefully examined and any remedial work noted , such as cracks, unfilled holes, etc. This remedial work has to be completed before the walls can be insulated.

Gutters and down-pipes are examined for any leaks, blocks, or spillage and proper drainage.

The survey will take about 2 hours, and is free of charge.

The report and photographs are then uploaded to the CIGA platform for auditing.

This is a part of the greatly improved quality control measures found within the new free Cavity Wall Insulation in Wales Grant scheme.

Call us on 0800 8 10 10 60 or 07960 799681

My property has got damp. Should I have the cavity walls insulated?

Do not insulate damp walls


If there are any damp patches on your external walls then they should not be insulated.

The cause of the damp has to be resolved first.

In fact, if there is damp, the property will fail the CAS + ISA survey. Therefore, we will not be able to install free cavity wall insulation into damp walls.

To qualify for a Grant there must be a 25 year guarantee put in place.

To obtain a 25 year guarantee, the property must pass a CAS + ISA survey. So if there is damp there is no Government Insulation Grant – simples.

If it is “Black Mould / Spots” then this is probably Condensation and not Damp.

Statistics show that most of the time Condensation is a lifestyle issue rather than a structural issue. However, free Cavity Wall Insulation can help reduce/eradicate Condensation by keeping the internal walls warmer.

Call us on 0800 8 10 10 60 or 07960 799681

How is cavity Wall Insulation Installed?

Cavity wall insulation beads in Wales

Filling cavity walls is not a job you can do yourself.

We do the job in around 2-3 hours for an average semi-detached house with easily accessible walls. It is simple, quick – and with no mess.

We drill small holes (about 22mm in size) in the outside wall of your home. The holes are about 1 metre apart. We always insulate from bottom up.

The exact pattern of the holes is laid down in the British Board of Agrement (BBA) Certificate, which is issued for the material that is being used to insulate the walls.

We always use polystyrene beads.

We then blow the insulation into the cavity using special equipment. Once all the insulation is in, we fill the holes in the brickwork with cement. It is then colour matched to the render or mortar, so you’ll barely notice them.

Our Installers are among the best in the business. They have been insulating cavity walls for the past 45 years.

They will make good the holes with closely-matching filler. You will have a first-class result with the minimum of fuss and disruption.

Most of our customers are amazed at how quickly and neatly this operation can be carried out. Our work is also guaranteed for 25 years by CIGA – the Government backed Cavity Insulation Guarantee Agency.

Call us on 0800 8 10 10 60 or 07960 799681

Will Cavity Wall Insulation reduce my fuel bills?

heat loss through cavity wall in wales

Yes, free Cavity Wall Insulation will reduce your fuel bills.

These are the percentages of heat loss though the different parts of a house.

Walls = 35%.
Roof = 25%.
Floor = 15%.
Draughts= 15%
Windows = 10%

Free Cavity Wall Insulation in Wales will reduce the heat loss from the wall by 70%.

For a 3 bed semi detached house on mains gas this would amount to about £160 per year. For other fuels such as Oil, Coal, LPG and Electricity the savings would be considerably more.

It can also help reduce/eradicate Condensation.

It can also reduce carbon emissions by up to 3 tonnes per year, therefore reducing your carbon footprint.

The Government regards cavity wall insulation as “the most effective energy savings measure that most people can carry out on their homes” and a major contributor to reducing carbon emissions.

Call us on 0800 8 10 10 60 or 07960 799681

Is the Cavity Wall Insulation guaranteed?

CIGA 25 year guarantee for cavity wall insulation in Wales

Yes, our free cavity wall insulation comes with a 25 year guarantee issued by the Cavity Insulation Guarantee Agency (CIGA).

The Cavity Insulation Guarantee Agency provides independent 25 year guarantees for Free Cavity Wall Insulation in Wales.

However, they will only issue a guarantee if the property has passed a CAS survey.

A grant will not be allowed unless a CIGA guarantee is issued.

CIGA was established in consultation with the Government’s Energy, Environment and Waste Directorate (a division of DETR) to provide householders with an independent, uniform and dependable guarantee covering defects in materials and workmanship.

Independent research carried out for the Department of the Environment, Transport and the Regions (DETR) has confirmed that cavity wall insulation is a very reliable process.

Problems are therefore extremely rare, but if they do occur, CIGA has the expertise to ensure that they are swiftly rectified.

The new CAS survey will also reduce the potential for future problems, by only insulating walls that are suitable.

CIGA also operates and administers the Cavity Wall Insulation Self Certification scheme (CWISC) in association with the British Board of Agrément. The scheme provides homeowners with the comfort of knowing that work by registered contractors complies with the requirements of the Building Regulations.
Call us on 0800 8 10 10 60 or 07960 799681

Can Cavity Wall Insulation cause Damp?

According to the Cavity Insulation Guarantee Agency, damp problems arise in 3 houses out of every 1,000 insulated.

The problems of damp and cavity wall insulation (CWI) are virtually all historical,and were caused by inappropriate insulation being put into inappropriate walls.

Rockwool used to be the main insulation used for free Cavity Wall Insulation in Wales. This has now been replaced by polystyrene bead which is a much better material for Cavity Wall Insulation.

Even so, when polystyrene beads were first used they used the little white soft polystyrene beads, just like the ones found in “bean bags”. In some cases these also caused issues – mainly due to their small size, structure and not being very good at repelling water.

Today, larger grey polystyrene beads, shaped like half a coffee bean or a mix of differently sized beads are used. These beads are also impregnated with a water repellent.

But the main problem was caused by salespeople knocking doors telling people they could have CWI for free, and then not carrying out a full pre-installation survey. As a result of this, houses that should never have been insulated were insulated.

A massive improvement in quality control

In April 2017 the British Board of Agrément (BBA), was put in charge of ensuring that “inappropriate” houses should not be insulated.

This gave birth to the Cavity Assessment Surveillance Scheme (CASS).

The BBA are the body responsible for certifying that building materials are “fit for purpose”. They lay down how building materials should be used within the certificate that they issue for that material.

In October 2018 CIGA took over the helm of this scheme.

CAS involves a full survey of the property to be insulated which takes about  2 hours to complete. The survey of your property includes, but is not limited to, camera shots of the inside of the cavity and other factors which may make a property inappropriate to insulate.

These would include factors such as the age of property, condition of walls, depth of cavity, construction type, condition of gutters and down-pipes, and rubble in the cavities, etc.

Leaky gutters and down-pipes is one of the main causes of damp in homes.

The photographs and other data are then uploaded onto the CIGA platform for auditing. Every survey is audited by CIGA at desktop level.  1 in 10 are audited with a visit to the property by a CIGA surveyor to audit the survey that had been carried out.

“This level of “quality control” should resolve the historical problem of insulating inappropriate properties, and therefore reduce the potential for damp caused by Cavity Wall Insulation.”

Up to 2017 CIGA states that there could be problems in 3 out of every 1,000 properties who have had CWI installed, but the CAS survey should greatly reduce this figure even further.

Find out if you qualify for a grant or give us a call us on 0800 8 10 10 60 or 07960 799681 to speak with one of expert advisers.

Should you have not found an answer to your question please give us a call on

0800 8 10 10 60 or 07960 799681

where one of our expert advisors will be pleased to help you.

Give us a call now on 0800 8 10 10 60 or 07960 799681

or book a free no obligation survey.

The Green Deal Wales came and surveyed the walls of my home for Cavity Wall Insulation. The survey took more than 2 hours, but it passed. Booked it in to be done but the corona lockdown delayed it. Now it’s done and they did a good job. Looking forward to a warmer winter and lower gas bills. Great company.
George P.  Llanmartin. June 2020.