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What is Wall Cavity Insulation Grant And Who Qualifies

Written by, Marija Petkova

Updated June, 23, 2023

It is estimated that quality wall cavity insulation can reduce heat loss up to 35%, allowing you to warm your home more efficiently and cut down on electricity bills. 

However, wall insulation is a costly procedure that must be carried out by a professional. The good news is if you qualify for a wall cavity insulation grant, you can get it done for free. 

Let’s take a look at who is eligible and how you can apply for a free cavity wall insulation grant.

What is Cavity Wall Insulation?

Simply put, a cavity wall is two walls with a gap in between—the external wall is usually made of brick, whereas the internal layer is brick or concrete. 

Homes built between 1924 and 1982 are most likely to need cavity wall insulation. Houses built before the 1920s typically have solid walls (so no cavity), while homes constructed after 1990 already have built-in insulation. 

How can I tell if my walls have a cavity?

The best way to tell is by looking at the brickwork.

If the bricks are oblong and laid end-to-end, chances are the wall has a cavity. Solid walls, on the other hand, have an alternating pattern, so some bricks will be laid across the wall, allowing you to see the ends of the bricks.

If the brickwork is not exposed, check the thickness of the wall next to a door or window. In general, if your walls are 260 mm or thicker, they probably have a cavity. 

How does cavity wall insulation work?

Cavity wall insulation involves filling the cavity between the walls with some kind of insulating material, i.e. material that stops heat transfer. This is usually shredded mineral wool, polystyrene beads, polyurethane foam or glass fibre—a surveyor will determine which material should be used depending on the cavity, the size of the home and the location. 

The material captures the air within the cavity, preventing heat loss, which leads to warmer homes and lower heating bills by up to £690 annually. It will also increase the energy efficiency of your home and reduce your carbon footprint by up to 1200 kg.  

Insulating wall cavities in a detached house can cost £1,800 or around £580 for a mid-terraced house. The Energy Saving Trust estimates that you should be able to get back your investment in 5 years through lower energy bills.

Other benefits of having wall cavities insulated include:

  • You would increase the value of your home
  • No maintenance is required 
  • Foundation weight is reduced

What Are Cavity Wall Insulation Grants?

Under the government-backed ECO-scheme, energy companies with 150,000 customers and over are obligated to provide free boiler replacements (replacing older gas models with energy efficient ones), wall cavity and solid wall insulation (external and internal), smart heating controls and loft insulation to low-income households with low-energy efficient homes. 

This is done in an effort to reduce households’ carbon footprint and improve the homes’ EPC rating. In fact, the ECO4 Scheme aims to bring band F and G homes to at least a D rating, whereas D-rated homes should reach a C rating or higher.

Who qualifies for grants for cavity wall insulation?

To be able to get a cavity wall insulation grant, you need to

  • Own the home
  • Have a home that is not energy efficient (EPC rating D or lower)
  • Receive certain means-tested government benefits, including
    • Working Tax Credits
    • Universal Credit
    • Child Tax Credits
    • Pension Guarantee Credit
    • Pension Savings Credit
    • Child Benefit*
    • Housing Benefit
    • Income based jobseekers allowance (JSA)
    • Income Support
    • Income Related Employment & Support Allowance (ESA)

*Recipients of Child Benefit must also meet income thresholds which range from £19,800 to £34,200 for single claimants, and from £27,300 to £41,700 for members of a couple. 

Most installers also require the house to be occupied and the wall area to take up at least 60% of the property size (which means extensions won’t qualify).

What if I don’t receive benefits?

If you are not on government benefits, you could still be eligible for a government grant for cavity wall insulation under the ECO4 Flex scheme. This programme allows your Local Authority to award a cavity wall insulation grant to residents that meet their qualifying criteria. 

Generally, the ECO4 Flex scheme targets low-income households and those who receive non-means tested benefits like Disability Living Allowance, Carer’s Allowance and Armed Forces Independence Payment.

Who supplies grants for wall insulation?

Most of the utility companies operating in the UK are part of the ECO scheme. These include British Gas, E.ON, EDF Energy, Scottish Power, OVO and others. You can find the full and updated list on Ofgem’s official site

How to apply for cavity wall insulation grants?

If you qualify, contact your energy provider and see what grants they offer in your area. They will arrange a survey of the home to determine whenever you need cavity wall insulation. 

Bear in mind that installation should be free, although if the situation is especially complex, you might be required to contribute to the overall cost. If this is the case, you are under no obligation to go ahead with the process. 

How much can I get with a cavity wall insulation government grant?

The amount of the grant for cavity wall insulation you receive depends on the size of the property, the current heating system and type of home. The more you can save with wall cavity insulation, the higher the grant will be, which means bigger homes with off gas heating systems tend to take priority over smaller properties. In general, expect the grant to reduce the cost by £500 to £600.

Interested in getting more freebies? Take a look at which banks give you money for opening an account. 

Is my home suitable for a cavity wall insulation grant?

Cavity wall insulation, when done right and on eligible properties, can result in lower heating bills. However, when it is poorly installed or placed in homes that do not need wall cavity insulation it could lead to serious damp and mould issues, which could affect your health and cost thousands of pounds to fix. 

How to tell if your home needs cavity wall insulation?

One deciding factor is the location

If you live in an area where your walls are exposed to wind-driven rain or extreme weather your home might not be suitable for cavity wall insulation. This applies mostly to areas located in the west of the country, i.e. south-west and north-west England, north-west Scotland and west Wales, which might be why the latest energy stats show residents in these regions spending more on heating and electricity than the average UK household.  

You home is also likely to need wall cavity insulation if:

  • Your external walls are unfilled cavity walls. Homes that have had cavity wall insulation fitted later will have drill holes on the outer walls (where the material was blown into the cavity). You can also check whether your home has cavity wall insulation by checking your EPC here (or here for Scotland) or have a registered installer check your walls. 
  • There is a 5cm wide cavity or wider
  • Your house is not at risk of flooding 
  • It was built between 1920 and 1990
  • The masonry or brickwork on your property is in solid condition

If your house is not the best candidate for cavity wall insulation, but you still have problems with heat loss, consider solid wall or loft insulation. Both loft and solid wall insulation grants are available through the ECO4 programme, and the same eligibility criteria apply. 

What is cavity wall insulation removal?

In 2005, the government provided grants for cavity wall insulation for all homes built between 1982 and 2005 (building regulations after 1982 required wall cavity insulation to be installed on almost all new constructions, however, not all of them complied). In some cases, though, wall cavity insulation was fitted on homes that were not suitable or was improperly installed, leading to severe mould, moisture and vermin issues. 

A surveyor will be able to tell if the wall cavity insulation in your home was not properly installed or is deteriorating, in which case it will have to be replaced. They will also inform you if your home is not suitable for wall cavity insulation, resulting in the removal of the insulation material.

Final things to consider

  • Ensure that your installer is registered with the Cavity Insulation Guarantee Agency (CIGA). Energy companies are obligated to meet certain targets under the ECO4 programme which might lead to installers pushing insulation without it being quite necessary. 
  • If you have problems with your insulation, contact CIGA. Cavity wall insulations have a 25-year warranty, when done by registered installers, so CIGA might be able to cover the cost of repairs up to £20,000. If they do not help you, you could go to an independent arbitrator run by the Centre for Effective Dispute Resolution or contact some of the volunteer-led organisations which can give you advice on how to proceed. 
  • If you live in an area that is exposed to flooding, you might have to get your cavity walls insulated with foam, which is costlier. 
  • Internal walls with damp patches should not be insulated until the issue is resolved. 
  • Flats cannot be insulated on their own—usually, the entire block needs to be involved. 

Frequently Asked Questions And Their Answers

Can I get a grant for wall insulation if I live in a semi-detached house?

Yes, if you meet the criteria, you could get a wall cavity insulation grant even if you don’t live in a detached house. The installer will insert a cavity barrier so that your neighbour’s home is not affected.

How long does wall cavity insulation take?

Professional installers will drill small holes into the exterior walls and blow insulation into the cavity. The entire process takes about two hours, provided the house is not too big and the walls are easily accessible.

Can I insulate the wall cavity myself?

No, this is a job that needs to be completed by a professional. If you are spending too much on heating and suspect it is caused by uninsulated walls, check to see if you qualify for a wall cavity insulation grant.

My name is Marija, and I'm a financial writer at DontDisappointMe. Although finance might not be everyone's cup of tea, my 10+ years of working in one of the biggest banks in my country, and my interest in extensive research on everything finance/investment-related, have made me somewhat of an expert in the field (if I do say so myself). No longer having the passion to work in a corporate setting, I decided that I couldn't let all of this knowledge go to waste so I started writing. And, here I am! Today I try to share my knowledge with my audience in the hopes of making this topic as simple and interesting as possible. In my leisure time, I like spending time with my family and travelling to new locations.