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Cavity wall insulation
Cavity wall insulation is one of the most cost-effective ways to stop heat escaping. Here’s how it works and who it suits.
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An easy upgrade that could cut hundreds off your energy bills
If your home was built after the 1920s, there’s a good chance it has cavity walls — and if they haven’t been insulated yet, you could be losing a significant amount of heat every day.
Cavity wall insulation is a simple, cost-effective way to keep the warmth in and the cold out. It involves filling the gap between the inner and outer layers of your external walls with insulating material that traps heat and reduces energy waste.
The best part? Many households can now get this upgrade fully funded through government-backed schemes like ECO4 and the Great British Insulation Scheme (GBIS).
What is cavity wall insulation?
Cavity walls are made of two layers of brick or block with a small air gap (the cavity) between them. Insulating this cavity significantly reduces heat loss and helps maintain a stable indoor temperature.
The insulation is:
- Installed from the outside of your property
- Blown into the cavity through small drilled holes
- Quick to install — usually completed in just a few hours
- Suitable for most homes built between the 1920s and 1990s
Is your house suitable?
Most cavity wall properties are suitable, but we’ll carry out a full property survey to be sure.
Cavity wall insulation may be right for you if:
- Your home was built between 1920 and 1990
- External walls are unfilled cavity walls at least 50mm wide
- The walls are accessible from outside
- Your property is not prone to severe damp
- You do not already have insulation in place
If your home isn’t suitable, we’ll recommend a better option — such as internal or external wall insulation.
Can I get cavity wall insulation for free?
Yes. Cavity wall insulation is one of the most commonly funded measures under both ECO4 and GBIS.
You could be eligible for full funding if:
- You receive certain means-tested benefits
- Your income is below £31,000 or have a long term medical condition
- Your home has an EPC rating of D, E, F, or G
- You live in a Council Tax band A–D (or A–E in Scotland/Wales)
Not sure where you stand? We’ll check for you.
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Frequently Asked Questions
What types of insulation do you install?
We install loft insulation, cavity wall insulation, internal wall insulation, underfloor insulation, and room-in-roof insulation — depending on your home’s needs.
Why is insulation important?
Insulation keeps heat in and cold out, helping you stay warm, reduce draughts, and lower your energy bills.
Is insulation messy to install?
Most types of insulation are quick and clean to install, with minimal disruption. Our team is tidy, respectful, and efficient.
Can I get free insulation?
Yes — if you’re eligible for ECO4 or GBIS funding, your insulation could be fully covered. We’ll check your options during your assessment.
How long does it take to install insulation?
Loft and cavity wall insulation can usually be done in a few hours. Other types may take a bit longer depending on the property.
Will insulation really make a difference?
Absolutely. A properly insulated home can be warmer in winter, cooler in summer, and significantly cheaper to heat.