This is a list of Cavity Wall Insulation FAQs.
Lower your fuel bills. Reduce your carbon footprint. Improve your home’s comfort.
If your home has uninsulated cavity walls, you’re likely losing up to 35% of your heat through the walls alone. That’s money — and warmth — literally escaping from your home.
Why Insulate Your Cavity Walls?
Here’s how heat typically escapes from an uninsulated home:
- Walls – 35%
- Roof – 25%
- Floor – 15%
- Draughts – 15%
- Windows – 10%
By installing cavity wall insulation, you can reduce wall-related heat loss by up to 70%. This translates to an estimated 24.5% reduction in your overall heating bills (because 70% of 35% = 24.5%).
🔸 Be cautious of misleading claims.
Some companies suggest savings of 35% or more, but no insulation can fully eliminate heat loss through walls. A 24.5% reduction is a realistic, evidence-based estimate.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
Yes, the UK Government Grant Scheme is called the Great British Insulation Scheme.
To meet legally binding targets for reducing carbon emissions, the UK government has introduced various measures. One of the key initiatives is the Great British Insulation Scheme, part of a wider programme called the Energy Company Obligation (ECO).
Under the ECO, energy companies (like gas and electricity suppliers) are legally required to help reduce the UK’s carbon footprint. They do this by funding energy efficiency improvements, such as free cavity wall insulation for eligible households.
But where does the funding come from?
We all contribute through our energy bills. A portion of what we pay—known as the “green levy”—is allocated to support these environmental initiatives:
- Around 6% of your gas bill
- And 11% of your electricity bill
This money is pooled and used by energy companies to deliver the ECO grants. So while the insulation might appear “free” at the point of use, it’s actually indirectly funded by consumers through these levies.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
If you have noticed damp patches on the inside of your external walls, it’s crucial to address these before proceeding with any insulation installation.
If a property suffers from damp, it will fail the CAS (Cavity Assessment Survey), and cavity wall insulation cannot be installed under the Great British Insulation Scheme (GBIS).
This is because, to qualify for a grant, a 25-year guarantee must be issued, which is only possible if the property passes the survey. If the property has damp, it will fail the CAS survey, and no grant will be approved—plain and simple.
However, if you see “black mould or spots,” this is likely caused by condensation rather than structural damp.
In about 90% of cases, condensation results from lifestyle factors, such as inadequate ventilation or drying clothes indoors, rather than issues with the building itself.
Cavity wall insulation can help mitigate this by keeping the internal walls warmer, which can reduce or even eliminate black mould caused by condensation.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
Can Cavity Wall Insulation reduce condensation/black mould?
Yes, cavity wall insulation can reduce condensation and black mould, especially in homes like those in Wales, where damp conditions are common.
✅ How It Helps:
Condensation forms when warm, moist indoor air hits cold surfaces, like uninsulated walls. That’s when water droplets form, and over time, black mould follows.
Cavity wall insulation works by:
- Keeping internal wall surfaces warmer reduces the temperature difference.
- Minimising cold spots where condensation is likely to form.
- Improving overall energy efficiency, which helps maintain more consistent indoor temperatures.
This makes your walls less prone to attracting moisture and mould.
⚠️ Important Considerations:
- Cavity wall insulation must be installed correctly and only in suitable properties (e.g., not where walls are exposed to persistent wind-driven rain without protection).
- Ventilation is still essential—insulation doesn’t replace the need for airflow. You may also need extractor fans or trickle vents to manage moisture from cooking, showers, and drying clothes indoors.
Summary:
✅ Yes — free cavity wall insulation can significantly reduce condensation and mould risk, especially when paired with good ventilation. For a Welsh home, where moisture is a frequent issue, this could make a real difference to comfort and health.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
CIGA Guarantee for Free Cavity Wall Insulation
Free cavity wall insulation comes with a 25-year guarantee issued by the Cavity Insulation Guarantee Agency (CIGA).
CIGA is an independent body that provides long-term protection for cavity wall insulation installed by registered professionals across the UK and the Channel Islands, including Wales. This guarantee covers any faults in materials or workmanship, giving homeowners peace of mind.
However, the guarantee is only issued after a property passes a Cavity Assessment Survey (CAS) to ensure that the walls are suitable for insulation. Without this survey and the CIGA guarantee, the grant funding cannot be approved.
Cavity wall insulation is widely recognised by the UK government as one of the most cost-effective energy-saving measures, playing a key role in reducing household energy bills and carbon emissions.
CIGA was originally established in partnership with the government’s Energy, Environment, and Waste Directorate (part of the now-defunct DETR). Over the years, it has built a strong reputation for managing rare issues quickly and professionally.
In addition, CIGA operates the Cavity Wall Insulation Self Certification Scheme (CWISC) in collaboration with the British Board of Agrément. This ensures all installations carried out by registered contractors comply with building regulations and quality standards.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
Why We Use “SuperBead” for Cavity Wall Insulation — Not Mineral Fibre
We exclusively install “SuperBead” polystyrene beads for cavity wall insulation. We do not use mineral fibre products like “RockWool.”
Watch our 6-minute video to see how cavity wall insulation works and why “SuperBead” does not cause damp.
Why Choose “SuperBead”?
“SuperBead” is a premium insulation material, offering several advantages over traditional mineral fibre options, though it does come at a higher cost. Its performance and reliability make it the smart choice for long-term energy savings and moisture control.
✅ Key Benefits of “SuperBead” Insulation:
- Thermal Efficiency
With a thermal conductivity of just 0.035 W/mK, SuperBead helps retain heat more effectively, improving energy performance. - Water Resistance
The beads resist water transfer through the cavity, helping prevent damp and mould from forming. - Condensation Control
By keeping internal walls warmer, SuperBead helps minimise condensation risk, creating a healthier indoor environment. - Fire Safety
SuperBead does not compromise your home’s fire resistance and is certified safe for residential use. - Durability
It is rot-proof, water-resistant, and designed to last for the lifetime of your property. - Proven Performance
SuperBead is up to 20% more efficient than fibre-based insulation and reduces heat loss through walls by around 70%.
Efficient Installation Process
The beads are blown into the cavity along with a special adhesive that sets within 20 minutes, forming a solid, continuous layer of insulation. This process:
- Requires 30% fewer and smaller holes in the outer wall compared to fibre options
- Causes minimal disruption
- Leaves a seamless thermal barrier inside your cavity walls
Certified & Safe
SuperBead has been rigorously tested and is certified by the British Board of Agrément (BBA) for use even in exposed or harsh weather conditions.
Before any installation, we carry out a Cavity Assessment Survey (CAS) to ensure your home is suitable. This step is a part of the upgraded standards under the Great British Insulation Scheme (GBIS)—previously known as the Free Insulation Scheme.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
You can watch this 6-minute video to see the full process in action.
We insulate cavity walls by blowing polystyrene beads into the wall cavity, typically from the outside. In some cases, internal access can be used if needed.
✅ Step-by-Step Installation Process:
- Drilling the Access Points
Small 22mm holes (just under the size of a 2p coin) are drilled into the external walls. The drill pattern follows strict guidelines set by the British Board of Agrément (BBA) to ensure even coverage. - Injecting the Insulation
Using specialist equipment, we inject the SuperBead polystyrene beads along with a fast-setting adhesive. Within 20 minutes, the beads bond into a solid insulating layer within the wall cavity. - Finishing Touches
Once the cavity is filled, all drill holes are sealed with colour-matched cement to blend in with your existing brickwork or render, leaving a neat and discreet finish.
⚠️ Professional Installation Only
Cavity wall insulation is not a DIY task. For a typical 3-bedroom semi-detached home, installation takes around 3 hours from start to finish.
Many of our customers are pleasantly surprised by how quick, tidy, and non-disruptive the process is.
🛡️ 25-Year Guarantee for Peace of Mind
All work is covered by a 25-year guarantee from CIGA (Cavity Insulation Guarantee Agency), an independent, government-backed body. This ensures long-term protection and reassurance.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
Benefits of Cavity Wall Insulation
Cavity wall insulation offers a wide range of advantages for homeowners, both immediate and long-term. Here’s what you can expect:
✅ 1. Improved Energy Efficiency
Insulation significantly reduces heat loss through your walls, helping your home retain warmth more effectively. This means your heating system doesn’t have to work as hard to maintain a comfortable temperature.
💷 2. Lower Energy Bills
With less heat escaping, you’ll use less energy to heat your home, leading to noticeable savings on your heating bills over time. Cavity wall insulation can reduce wall-related heat loss by up to 70%. This translates to an estimated 24.5% reduction in your overall heating bills
🏡 3. Greater Indoor Comfort
Insulation eliminates cold spots and reduces drafts, creating a more consistent and comfortable indoor climate all year round.
🌍 4. Reduced Environmental Impact
By using less energy for heating, your home produces fewer carbon emissions, helping to lower your environmental footprint.
💧 5. Condensation & Damp Control
Warmer internal wall surfaces help prevent condensation from forming, reducing the risk of damp patches and black mould.
📈 6. Boosted Property Value
Energy-efficient improvements like cavity wall insulation are attractive to buyers and can increase your property’s value, especially as energy ratings become more important.
🔇 7. Better Soundproofing
Insulation also provides a degree of noise reduction, making your home quieter, particularly beneficial if you live near a busy road or in a noisy area.
⏱️ 8. Fast, Low-Disruption Installation
The entire process usually takes around 3 hours for a typical semi-detached home, with minimal mess or disturbance.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
You will need to be in receipt of a Government qualifying benefit (including child benefit. See below).
Here is the list of Qualifying Benefits.
- Pension Credit
- Income-Based Job Seekers’ Allowance
- Universal Credit – No income threshold
- Income-Related Employment and Support Allowance
- Tax Credits (including Working and Child Tax Credits) – No income threshold
- Income Support
- Housing Benefit – NEW
- Child Benefit/Family Allowance. Income Thresholds apply – see table below. These are gross (before stoppages) thresholds.
| Number of Children | 1 Adult Household | 2 Adult Household |
|---|---|---|
| 1 | £19,900 | £27,500 |
| 2 | £24,800 | £32,300 |
| 3 | £29,600 | £37,200 |
| 4 | £34,500 | £42,000 |
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
We Handle Everything – Stress-Free and Hassle-Free
When you choose us, there’s no paperwork or chasing forms—we take care of it all.
✅ During your free survey, we’ll:
- Check your eligibility for funding
- Manage the entire grant application on your behalf
✅ After installation, we:
- Submit the grant claim
- Receive payment directly from the scheme provider
- Send you your 25-year guarantee
99% of the time, there’s nothing for you to pay and no admin to worry about. Occasionally, there may be a small contribution to make, but you will be made aware of that before any work is carried out.
All you need to do is sit back, relax, and enjoy:
- Lower energy bills
- A warmer, more comfortable home
- A reduced carbon footprint
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
Damp and Cavity Wall Insulation: What You Need to Know
According to the Cavity Insulation Guarantee Agency (CIGA), damp problems related to cavity wall insulation (CWI) occur in around 3 out of every 1,000 homes. In nearly all cases, these issues are linked to inappropriate materials being installed in unsuitable walls.
A Look Back: Early Materials and Mistakes
Historically, Rockwool was widely used for cavity wall insulation. However, it has largely been replaced by polystyrene beads, which offer better thermal performance and moisture resistance.
Rockwool is a fibre. Fibres suck up water through capillary attraction. The fibres get heavier and move down the cavity. They eventually clump at the bottom of the cavity, making a pathway to the inside wall and ultimately damp.
Early versions of polystyrene beads—similar to the soft, white beads found in bean bags—were not water-repellent. In some cases, these outdated materials actually contributed to damp problems.
Today, cavity wall insulation uses modern grey or silver polystyrene beads of varying sizes. These are specifically engineered to repel water, helping to prevent moisture from travelling across the cavity.
The Real Issue: Poor Installation Practices
In the past, some installers cut corners, promising “free insulation” without carrying out proper surveys. As a result, insulation was sometimes installed in homes with:
- Damaged or shallow cavities
- Leaky gutters or downpipes
- Inadequate damp-proof courses
This led to a small percentage of homes experiencing damp issues.
Improvements in Quality Control: The CASS System
In April 2017, the British Board of Agrément (BBA) launched the Cavity Assessment Surveillance Scheme (CASS) to address these problems by ensuring only suitable homes are insulated. In October 2018, management of the scheme was passed to CIGA, and it is now run by the Insulation Assurance Authority (IAA).
🛠️ How the CASS Survey Works:
- A comprehensive survey (typically 2 hours) is carried out before approval of the installation.
- Surveyors assess wall condition, cavity depth, existing damp-proofing, and external factors like gutters and downpipes etc.
- Photographic evidence of the cavity is collected and submitted to the IAA for review.
- All surveys undergo a desktop audit, and 1 in 10 homes is selected for an on-site inspection by an IAA surveyor.
This process ensures that only homes truly suitable for cavity wall insulation are approved, greatly reducing the risk of future damp.
Looking Ahead: A More Reliable System
Before 2017, the reported damp incidence was about 0.3% (3 in 1,000 homes). With the introduction of CASS and stricter quality control, this figure is expected to fall even further, giving homeowners more confidence in the safety and effectiveness of cavity wall insulation.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
You can find your EPC on the EPC Register. ✔
If you don’t have an EPC (Energy Performance Certificate), you can still apply for a Cavity Wall Insulation grant using The Great British Insulation Scheme.
As a part of the required survey, we produce an EPR (Energy Performance Report). An EPR uses the same dataset as an EPC, but it is not registered, and you don’t get a certificate.
So, you don’t need to have an EPC!
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
What Is an EPC?
EPC stands for Energy Performance Certificate. It provides an energy efficiency rating for a property, giving an idea of how much it will cost to heat and power the home.
You can find your EPC on the EPC Register. ✔
When Is an EPC Required?
An EPC is legally required if you are:
- Selling a property
- Renting out a property
EPCs were introduced on 1st August 2007. So, if you purchased your home before that date and haven’t sold or rented it since, you probably haven’t one.
How Long Is an EPC Valid?
An EPC is valid for 10 years from the date it’s issued. For example, you can sell a property with a 7-year-old EPC, but bear in mind that it might not reflect any recent energy improvements.
There has been discussion about reducing the validity period to 5 years to make EPCs more up-to-date and relevant.
How EPC Ratings Work
EPCs are rated on a scale from A to G:
- A = Most energy-efficient (lowest heating costs)
- G = Least energy-efficient (highest heating costs)
The rating is based on an average occupancy of 2.5 people and looks at the estimated cost of heating the home and providing hot water.
Upcoming Changes
From June 2025, the government have updated how EPCs are calculated. These updates will use more accurate data and provide a clearer picture of a property’s real-world energy use and carbon impact.
Do You Need an EPC for The Great British Insulation Scheme
No.
Even if you don’t currently have an EPC, you can still apply for a cavity wall insulation grant.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
Is Your Home Suitable for Cavity Wall Insulation?
Solid stone or solid brick walls do not have a cavity and therefore cannot have cavity wall insulation. Not all homes with cavity walls are suitable for insulation either. A proper survey is always essential to determine whether insulation is appropriate and safe for your property.
🧱 Understanding Wall Types
Before 1920, most UK homes were built with solid walls—either stone or solid brick (two layers of brick laid side by side). These walls had no cavity and were often prone to damp, which could lead to serious health issues like pneumonia.
To address this, cavity wall construction was introduced. This design features two layers of brick or block with a gap (or cavity) in between to prevent moisture from travelling into the home.
- By the 1920s, cavity walls became more common
- By 1930, they were the standard in most new builds
🏡 Which Homes Are Typically Suitable?
- Homes built after 1930 usually have cavity walls and may be suitable for insulation
- However, a professional survey is always required to confirm suitability
⚠️ Key Exceptions – Homes That May Not Be Suitable:
- Concrete Properties
Often, former council houses. These homes may have unfilled cavities. Insulating them can risk causing structural issues like “concrete cancer”, making them unsuitable. - Timber-Framed Homes
These use a wooden frame with insulation already built in behind the outer brickwork. Adding cavity wall insulation here can cause moisture problems and is not recommended. - Homes Built After 1982
Building regulations required insulation from this point onward. However, many homes built in the 1980s, 1990s, and even early 2000s were left without adequate insulation. These properties may still qualify, pending a detailed survey.
🛠️ Survey First, Insulate Second
Every property is different. That’s why a Cavity Assessment Survey (CAS) is required before any work is approved or carried out. This ensures:
- Are the cavities already filled?
- Are the walls structurally sound?
- Is there no existing damp?
- Is the property a safe candidate for insulation?
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
There are 2 routes to qualifying for a grant.
- The General Group.
- The “low-income” Group.
The General Group qualification for a grant.
Two ✔’s and you qualify.
- Your Council Tax Banding in Wales is A, B, C, D or E (or in England A to D). You can find your Council Tax Banding on Gov.Uk ✔ and
- Your EPC (Energy Performance Certificate) rating is a D, E, F or G. You can find your EPC on the EPC Register. ✔
These rules apply to both owner-occupiers and privately renting tenants (with Landlord’s consent). However, for Cavity Wall Insulation and Loft Insulation, privately renting tenants will need to be in receipt of a qualifying benefit as well.
The “Low Income” Group qualification for a grant.
The personal qualification criteria for the “low-income” group are benefit-based. The qualifying benefits are listed below. However, your EPC (Energy Performance Certificate) rating must be a D, E, F or G.
If you are a private tenant, your EPC will need to be a D or E. This is because it is illegal for a landlord to rent out a property with an EPC rating of F or G.
Here is the list of Qualifying Benefits.
- Pension Credit
- Income-Based Job Seekers’ Allowance
- Universal Credit – No income threshold
- Income-Related Employment and Support Allowance
- Tax Credits (including Working and Child Tax Credits) – No income threshold
- Income Support
- Housing Benefit – NEW
- Child Benefit/Family Allowance. Income Thresholds apply – see table below
Do I qualify for a Grant if I get Child Benefit?
Yes, you would qualify for a grant if you claim Child Benefit and have an annual income no greater than the appropriate threshold.
The threshold varies between single people and couples and depends on the number of children you have. See the table below. So, 2 adults with 2 children would have an income threshold of £32,300.
| Number of children | 1 | 2 | 3 | 4 |
| 1 adult household | £19,900 | £24,800 | £29,600 | £34,500 |
| 2 adult household | £27,500 | £32,300 | £37,200 | £42,000 |
The Great British Insulation Scheme was a “single insulation measure” grant scheme, but as of June 2025, loft insulation can be added as a secondary measure, so you can now get free cavity wall and loft insulation together.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
Is My Home Suitable for Free Cavity Wall Insulation?
The simple answer is:
“I can’t tell you for certain without carrying out a proper survey.”
However, there are some helpful indicators that can give you a good idea.
🧱 Does Your Home Have Cavity Walls?
If your property was built after 1925, there’s a strong chance it has cavity walls—two layers of brick or blockwork with a gap (or cavity) between them, held together with wall ties. This design became common from the late 1920s and helps reduce damp by stopping moisture from travelling through the wall.
In Wales, cavity wall insulation is a proven method for:
- Retaining warmth
- Lowering energy bills
- Reducing or even eliminating internal condensation
✅ Your Home Is Likely Suitable If:
- The external walls are cavity walls that are not already insulated
- The cavity is at least 50mm wide
- The brickwork or masonry is in reasonable condition
But even if these conditions are met, a professional assessment is still required.
🔍 What’s Involved in the Survey?
To ensure your home qualifies under the Free Cavity Wall Insulation Grant Scheme, a Cavity Assessment Survey (CAS) must be completed. This is carried out by trained surveyors and independently audited by the Insulation Assurance Authority (IAA).
During the survey:
- Small test holes are drilled into each external wall
- A borescope camera is used to inspect inside the cavity, take photos, and measure its depth
- Surveyors check for structural issues like cracks, unfilled holes, or signs of damp
- Gutters, downpipes, and drainage are examined for leaks or blockages
🕒 The survey takes around 2 hours, and there’s no cost or obligation to proceed.
Afterwards, all photos and data are uploaded to the IAA system, where they undergo a desktop audit to ensure your home is fully suitable and meets all safety and quality standards.
🏠 The Bottom Line
If your home was built after 1925 and has unfilled cavity walls, it may well qualify for free cavity wall insulation—but only a Cavity Assessment Survey can confirm it.
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs
To find out if you qualify, or to book a free, no-obligation survey, complete our enquiry form or give us a call
Complete Enquiry Form
or call us on 0800 8 10 10 60 or 07960 799681 and speak to one of our cavity wall experts.
Cavity Wall Insulation FAQs