Cavity Wall Insulation for UK Homes
Cut heat loss, lower your energy bills and make your home warmer all year round with professional cavity wall insulation from EnergyPlus.
Why cavity wall insulation matters
In many UK homes, up to 35% of heat is lost through uninsulated walls. If your property has cavity walls and no insulation, you are paying to heat the street. Cavity wall insulation is one of the quickest, most cost-effective ways to:
- Reduce your gas or electricity use for heating
- Lower your energy bills year after year
- Improve comfort with fewer cold spots and draughts
- Cut your household carbon footprint
- Increase the value and EPC rating of your home
EnergyPlus specialises in home energy improvements across the UK, helping homeowners and private tenants access high-quality insulation and available funding support.
Check if your home is suitable
Answer a few quick questions and our energy advisors will confirm whether cavity wall insulation is right for your property.
What is cavity wall insulation?
Most homes built in the UK from the 1920s onwards have cavity walls – two layers of brick or block with a gap (cavity) in between. Without insulation, cold air can circulate in the cavity and pull warmth out of your rooms.
Cavity wall insulation involves filling this gap with an approved insulating material. The insulation slows heat transfer through the wall, so your home stays warmer for longer and needs less energy to maintain a comfortable temperature.
Installed correctly by certified professionals, cavity wall insulation is discreet, permanent and maintenance-free, and usually pays for itself within a few years through lower heating bills.
How does the installation work?
EnergyPlus works with experienced, accredited installers who follow strict industry standards and manufacturer guidance. A typical installation for an average-sized house takes just a few hours and causes minimal disruption.
- Property survey – A trained surveyor checks your walls, masonry condition, exposure to wind-driven rain and access, and confirms suitability.
- Drilling pattern – Small holes (about 22mm) are drilled in the mortar joints on the outside walls following a set pattern.
- Insulation injection – The chosen insulation material is injected under controlled pressure to completely fill the cavity.
- Making good – Holes are filled and colour-matched as closely as possible so the finish blends with your existing brickwork.
- Final checks – The team ensures all areas have been filled correctly and tidies the site before leaving.
Most homeowners can remain in the property throughout the work and return to normal use immediately afterwards.
Instant benefits for your home energy
Once your walls are insulated, you should notice a difference straight away, especially during colder months. By reducing heat loss, your boiler or heating system doesn’t have to work as hard, which can lead to:
- Lower heating bills – Many households save hundreds of pounds a year, depending on property size and fuel costs.
- More stable room temperatures – Your home warms up faster and stays warm for longer.
- Less condensation on internal walls – Warmer surfaces can help reduce the risk of damp and mould caused by condensation.
- Improved EPC rating – Better insulation usually boosts your property’s Energy Performance Certificate grade.
Is my home suitable for cavity wall insulation?
Not all properties are the same, and it is important to get professional advice. Your home is more likely to be suitable if:
- It was built between the 1920s and late 1990s
- The external walls are made of brick and look like two layers rather than solid stone
- The cavity is at least 50mm wide and not already insulated
- The walls are in good condition with no significant cracks or structural issues
- Your property is not severely exposed to wind-driven rain without additional measures
If your home has solid walls or is a non-standard construction, other home insulation options may be more appropriate. Our advisors can talk you through the best solution.
Types of cavity wall insulation used
The exact material recommended for your home will depend on the construction, exposure and survey findings. Common options include:
- Mineral fibre – A tried-and-tested, non-combustible insulation that is blown into the cavity as loose fibres.
- Polystyrene beads or granules – Lightweight beads that flow easily around obstructions, providing good thermal performance.
- Foam systems – Specially formulated foams for certain wall types, used less commonly and always by trained specialists.
EnergyPlus only works with industry-approved products that meet British standards and carry appropriate certification. During your survey we will explain the options suitable for your property and why.
Cavity wall insulation costs & potential savings
The cost of cavity wall insulation depends on the size and layout of your property, access, and the type of insulation used. As a guide, for many typical UK homes:
- Smaller flats and bungalows may be towards the lower end of the cost range
- Larger detached houses will cost more but usually offer higher total bill savings
Because insulation works continuously for decades, the lifetime savings can be substantial. Many households recover the upfront cost in just a few years through reduced heating use.
EnergyPlus will always provide a clear, itemised quotation before any work goes ahead, so you know exactly what is included.
Grants and funding support
Depending on your circumstances and where you live in the UK, you may qualify for help with the cost of cavity wall insulation through schemes such as:
- Government-backed energy efficiency programmes
- Energy supplier obligation schemes (ECO and successors)
- Local authority or regional funding initiatives
Our team keeps up to date with the latest funding options and can check whether you may be eligible for full or partial support.
Common questions about cavity wall insulation
Will cavity wall insulation cause damp?
When installed in suitable properties after a proper survey, cavity wall insulation should not cause damp. Problems usually arise only when insulation is fitted in walls that are not appropriate, or where external defects such as damaged pointing, leaking gutters or cracked render have not been addressed. Our surveyors check for these issues before recommending any work.
How long does it last?
Cavity wall insulation is designed to be a long-term improvement. Once installed, it should last for the life of the building with no need for topping up or replacement under normal conditions.
Will it affect how my home looks?
Installation is carried out from the outside, and the small drill holes are filled using a closely matched mortar. Over time, these usually become barely noticeable. Inside your home, there is no visible change.
Is my home too old or too new?
Older homes (pre-1920s)
Many older properties have solid walls rather than cavities, so cavity wall insulation is not suitable. However, there are other effective options such as internal or external wall insulation, along with loft and floor insulation. Talk to us about the best approach for a traditional home.
Newer homes (post-1990s)
Most newer properties were built with insulation already installed in the cavity. If you are unsure whether your home is insulated, our team can help you check building records, EPCs or carry out a site assessment.
What about flats and maisonettes?
Flats can sometimes be insulated, but access and ownership arrangements are more complex. We can advise on options for individual leaseholders, freeholders and management companies.
Get your free cavity wall insulation quote
Share a few details about your home and one of our energy specialists will contact you to discuss options, funding and next steps.
Why choose EnergyPlus for your cavity walls?
- Home energy experts – We focus on making UK homes warmer, more efficient and more affordable to run.
- Fully accredited installers – We only partner with trusted contractors who meet recognised quality standards.
- Funding guidance – We help you explore available grants and support so you do not pay more than you need to.
- Honest advice – If cavity wall insulation is not right for your property, we will explain why and suggest alternatives.
Take the next step to a warmer, cheaper-to-run home
Cavity wall insulation is one of the most effective ways to improve your home’s energy performance. Whether you are looking to cut your bills, tackle cold rooms or simply future-proof your property, our team is here to help.
Start with a quick, no-obligation conversation and discover what is possible for your home.
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