Skip to content 
Table of Contents
Want to slash your energy bills and keep your home toasty warm? Cavity wall insulation might be just what you need! This guide explains everything in plain English – what it is, how it works, what it costs, and whether cavity wall insulation is worth the investment for your home.
With energy prices soaring across the UK, more folks are looking into energy-saving measures like this. Before you decide, let’s walk through the basics, from costs and savings to installation and potential issues like dampness.
What is Cavity Wall Insulation and How Does It Work?
Think of your home’s walls like a sandwich. Many UK homes have external walls made of two layers of brick with a gap (the cavity) in between. When this gap is empty, up to 35% of your home’s heat can escape right through the walls!
Cavity wall insulation is super simple:
- Installers drill tiny holes in your outside wall
- They pump insulation material into the gap
- They patch up the holes so you’d hardly notice they were there
This works like wrapping your home in a cosy blanket. It traps heat inside during winter and keeps your home cooler in summer. Your heating bills drop and so does your carbon footprint!
Air Source Heat Pump Grants
Does My Home Have a Cavity Wall That Can Be Insulated?
Did you get a home built after the 1920s? Then you probably have cavity walls that could be insulated.
How to know for sure? A professional can:
- Check your wall type
- Drill a tiny hole to peek inside the cavity
- Make sure the cavity is clean and dry
Not every home should get this done, though. If you’ve got damp issues, condensation problems, or damaged wall ties, you’ll need to fix those first.
What Types of Cavity Wall Insulation Materials Can I Choose From?
You’ve got several options, each with their own perks:
- Mineral wool: Perfect for most homes. It’s breathable and keeps heat in like a charm.
- Polystyrene beads: These tiny beads get blown into the cavity. They’re great at handling moisture and work around wall ties.
- Foam insulation: This thicker stuff is awesome for tricky spots or when you need extra warmth.
Which one’s right for you? It depends on your home’s age, size, and wall type. A good installer will help you pick the best fit.
How Much Will Cavity Wall Insulation Cost Me?
Prices vary based on your home size:
- Detached house: £700–£1,200
- Semi-detached: £450–£900
- Mid-terrace: £350–£700
- Bungalow: £400–£800
Yes, there’s an upfront cavity wall insulation cost, but here’s the good news – you could save up to £300 every year on energy bills! That means cavity wall insulation pays for itself in just a few years.
Even better? Some government schemes might cover some or all of the cost if you qualify. It’s definitely worth checking out!
How Long Does Cavity Wall Insulation Last?
When done right by professionals, your cavity wall insulation can last 25+ years!
Materials like mineral wool and polystyrene beads are tough cookies – they don’t break down easily. The key is proper installation and keeping your walls free from damp patches and mould.
Pro tip: If insulation is installed poorly or water sneaks in, you might need cavity wall insulation removal later. That’s why it’s worth using a CIGA-backed installer (Cavity Insulation Guarantee Agency).
Is Cavity Wall Insulation Worth It for Every Home?
For most homes, cavity wall insulation is absolutely worth it, especially if:
- Your home was built after the 1920s
- You have two walls with a clear cavity
- Your brickwork is dry and in good shape
- You don’t live in an area with extreme weather
It might not be the best choice if your walls often get damp or you live somewhere with lots of wind-driven rain. Cavity wall insulation might cause problems if your cavity already has junk in it or damaged wall ties.
Always get an insulation expert to check your home before you decide.
How Do They Install Cavity Wall Insulation?
The installation process is pretty straightforward:
- Pros check your brick and outer walls for damp signs and measure the cavity width
- They drill small holes (about the size of a penny) in the external wall in a diamond pattern
- They blow or pump the insulation into the cavity through these holes
- They fill the holes with cement or matching material when they’re done
The whole thing usually takes just a few hours. You won’t have workers camping out at your house for days!
Quick Recap: What You Need to Know About Cavity Wall Insulation
- It cuts your energy bills and boosts energy efficiency
- Most homes built after the 1920s with cavity walls can benefit
- You can choose from mineral wool, foam insulation, or polystyrene beads
- Expect to pay between £350 and £1,200 depending on your home size
- Good quality installation lasts 25+ years
- Always use a certified installer you trust
- Keep an eye out for damp signs after it’s done
- You’ll typically make your money back within a few years
- Different homes need different types of insulation
- Old insulation might need checking or replacing
Ready to get cosy and cut those bills? Cavity wall insulation might be one of the smartest home improvements you’ll make. It helps you save energy, shrinks your carbon footprint, and turns your house into a snug haven you’ll love coming home to!
Frequently Asked Questions
When done right, cavity wall insulation shouldn’t cause moisture problems.
But if your external wall already lets water sneak into the cavity, adding insulation can trap this moisture, leading to dampness or making existing problems worse. Homes with poor airflow might also build up condensation, causing dampness and mould.
Sometimes, using the wrong type of insulation material or sloppy installation can cause dampness in their homes, meaning you’d need the insulation removed later.
Already have insulation in your walls? Keep an eye out for problems. Over time, especially if it’s over 30 years old, insulation can settle or break down.
Watch for these red flags:
- Damp patches showing up on inside walls
- Cold spots in certain rooms
- Your heating bills suddenly shoot up
If you spot these, get an insulation expert to check if you need a top-up or complete cavity wall insulation removal.
Buying a house? Always ask if wall insulation for your home has already been done and if it comes with a CIGA guarantee.
The right installer makes all the difference! Look for:
- Companies with CIGA certification
- Glowing reviews from past customers
- Clear warranties that protect your investment
- Experience with your type of wall and insulation material
A trustworthy installer will be straight with you about whether your property is suitable and explain exactly how they’ll fill the cavity safely.
