Imagine standing next to an open window on a cold icy day feeling the winter draft. Now imagine feeling that heat loss across every external wall in your home - because that’s exactly what’s happening if you don’t have cavity wall insulation. Think of cavity wall insulation like a big cosy blanket that’s wrapping your walls up to keep the heat in.
Recent reports from The Department for Energy Security & Net Zero (DESNZ), showed that only 71% of all properties in the United Kingdom have cavity wall insulation installed.1 Meaning millions of homes are missing the chance to reduce their carbon footprint, save energy and reduce their energy bills.
But don’t worry - we’ve put together your own handy guide to explain cavity wall insulation and how you can take the next steps to make your home more sustainable whilst saving energy, time and money.
What is cavity wall insulation?
If your home was built in the last 70 or 80 years, your external walls are made of two “skins” (an inside and outside wall) with a gap or cavity in between them. Cavity wall insulation is simply insulating that gap by using shredded mineral wool (glass fibre), polystyrene beads or insulating foam.
Due to a building regulation change all homes built after 1982 should have cavity wall insulation. But the good news is if you don’t have it there’s many grants and schemes to help you get there.
Does cavity wall insulation cause dampness?
Cavity wall insulation, when installed correctly with the right materials, won't cause damp or mould in your home. In fact, cavity wall insulation itself doesn't lead to dampness. However, it's important to note that when installed correctly cavity wall insulation won’t cause damp or mould. But in some cases, fully filling the cavity with insulation can slightly increase the risk of rain penetration which can slowly lead to dampness.2
If your home already has damp issues, we'll need to address those before installing insulation.
For peace of mind, we’re Qualitymark accredited so your insulation comes with a 25-year guarantee.
How long does cavity wall insulation take?
Average three bedroom properties in the UK will take two to three hours.
How do I tell if I already have cavity wall insulation?
If you have an older property you are less likely to have cavity wall insulation, but you still might want to check. However newer properties should have it, as building regulations changed to require cavities to be fitted at the time of build.
If you’re still unsure, another way to tell is if your walls are at least 250 mm (10”) thick. If they are, your home is sure to have the “cavity walls” needed to pump insulation between. (scar marks on brick)
Your Energy Performance Certificate (EPC) may state ‘filled cavity’ if at the time of build you had cavity wall insulation.
How much does cavity wall insulation cost?
You may pay a few pounds for things like insulation tape and brushes for your windows and doors, right up to £2,700 for cavity wall insulation on your semi-detached house.3 However, there’s many government grants and schemes to help foot the bill and insulate your home.
It’s worth remembering that the cost of your insulation can be recouped in energy savings over time, and there is the added benefit of reducing your carbon footprint.
Who is eligible for the cavity wall insulation grant?
Luckily, people in the market for cavity wall insulation are met with numerous grants and schemes to get you there. But the first thing to remember is that your home must be privately owned or rented and occupied at the time of the survey (you wouldn’t be able to qualify if your house is currently being renovated).
Schemes like ECO4 and The Great British insulation scheme (GBIS for short) take things such as your EPC rating, council tax banding and benefits entitlement into consideration when assessing your application. But we’ll dive into those a little later.
Government grants and schemes.
GBIS will run until 2026 and make it easier to secure funding for cavity wall insulation alongside other home energy tech options. With the aim being to enhance the energy efficiency of low-income and fuel-poor homes, in line with the UK’s ambitious targets to reach net zero carbon emissions by 2050.
To see if you are eligible, or find out what we can offer - complete our free grant finder tool.
If you do not qualify, there are alternative schemes. You may be able to apply for similar schemes through your local council, or you can try other schemes for energy-efficient improvements, such as the Home Upgrade Grant, the Warm Homes Nest scheme (Wales only) and the Warmer Homes Scotland initiative.
If scaffolding is required to install cavity wall insulation, there could be a cost, but we’ll let you know before you decide to go ahead.
What’s the eligibility criteria for GBIS?
If you meet the following eligibility criteria you could benefit from free cavity wall insulation through the Great British Insulation Scheme (GBIS):
You're on qualifying benefits, and you are a homeowner with an EPC of D to G. Check your EPC rating.
Or you privately rent your home and have an EPC of D or E.
Or you are a homeowner and have an EPC rating of D or lower and a council tax band of A to D in England and A to E in both Wales and Scotland. Check your council tax band.
Check your grant eligibility online.
Homeowners, landlords, and tenants can all apply. However, tenants will need their landlord’s permission to proceed.
Unfortunately, the scheme is currently available in Northern Ireland.
Please be aware that eligibility does not guarantee free insulation and installation - other factors will be assessed to determine the level of discount you are eligible for, if any.
Benefits of cavity wall insulation.
You’re thinking of going through the effort of having cavity wall insulation, but you want to know it’s worth it right? Here’s a list of some of the benefits that go beyond energy saving and cost effectiveness that make cavity wall insulation yay rather than nay:
Contributions to a healthier planet: trapping the air in means that the temperature of your home can be maintained and you’ll be less likely to turn your heating on. So you’ll be reducing your carbon footprint without even thinking about it.
Healthier home: insulation helps maintain a stable indoor temperature and reduces humidity levels. By preventing heat loss in winter and heat gain in summer, insulation minimises condensation on walls and ceilings, which is a common cause of mould growth.
Less home maintenance: you can leave behind a few of your winter DIY hacks as cavity wall insulation has a lifespan of up to 25 years.
Increased home value: Buyers can see the value in a well-insulated home which could increase its value and sellability.
Quicker payback: One of the best ways to reduce your heating bill. So you potentially could save £240 each year.
Cavity wall insulation and air source heat pumps.
Fun fact time! Did you know that cavity wall insulation and air source heat pumps (ASHP) get along the same as solar panels and battery storage?
Switching to an ASHP is a great way to save money and help the planet, and it works even better when you've got cavity wall insulation! It's like a superhero team-up, keeping your home cosy and warm while slashing your energy bills. Plus, you'll feel fantastic knowing you're using renewable energy.
So why not give your home the dynamic duo it deserves - a more comfortable future is just a few steps away, get a quote today and start your journey to environmental stewardship.