Homes within the UK tend to have either cavity walls or solid walls.

Cavity walls have a space between the two layers of wall construction. If your home was built after the 1920’s then there’s a good chance it is a cavity walled property.

Cavity walls are insulated by injecting insulation into the space from the outside of your home, meaning minimal disruption.

Check if you are eligible for funding
How does it work?

Insulation material is injected into cavity walls from the outside.

Your installer will drill insulation injection holes in the exterior walls, fill them with insulation, and then seal them. Mineral wool or polystyrene beads are the two types of insulation that are typically utilised, but polyurethane foam can also be employed.

The installer drills tiny holes in your home’s exterior wall at intervals of around 1 metre to insulate the cavity walls. These holes are about 22 mm in size. The installer then uses specialised equipment to blast insulation into the cavity. Once all of the insulation is installed, the installer plugs the brickwork’s holes such that you hardly even see them.

Benefits of Cavity Wall Insulation

Save up to £690* per year on your bills

Reduce heat loss

Increase the value of your home

How do I know if my home has cavity walls?

If your home has brickwork similar to this, there’s a good chance it has cavity walls: 

Cavity Wall Insulation FAQ’s

How long does cavity wall insulation take to install?

Cavity wall insulation is quick and easy to install and takes approximately 1-2 hours depending on the size of your home. It involves minimal disruption and can be completed as part of wider energy efficiency upgrades.

What happens to the drill holes?

Your installer will fill the holes once the insulation has been installed by applying mortar. The installer will ensure the holes are filled with minimal visual impact to your home.

Can cavity wall insulation cause damp?

Cavity wall insulation will help to reduce any damp in your home by reducing heat loss and draughts. If installed by an experienced professional, it will provide a positive impact on the energy efficiency of your home.

Can I get funding to pay for cavity wall insulation?

You may be eligible for funding through the Energy Company Obligation Scheme.

Please complete our enquiry form to check if you’re eligible for ECO scheme funding.

Can cavity wall insulation cause any problems?

Provided the insulation is water-repellent and installed correctly, there should be no issues.

Installers should be registered with CIGA (Cavity Insulation Guarantee Agency) and their work will be covered by a 25 year guarantee, providing you with peace of mind.

Do I need planning permission for cavity wall insulation?

Not normally, however if you live in a listed property or are in a conservation area, we recommend consulting your local planning authority prior to install.

What funding is available?

The ECO4 scheme is available for cavity wall insulation in certain areas, check your ECO scheme eligibility here.

The Great British Insulation Scheme has funding for cavity wall insulation available now; check your eligibility.

Cavity Wall Insulation Grant

What is a free cavity wall insulation grant?

Individuals with lower incomes, as well as those who reside in the least energy-efficient houses or in lower council tax bands, are eligible for ECO grants.

How do grants for cavity wall insulation work?

First, your eligibility is based on a number of things, such as your household’s income, your EPC rating, and whether or not you get any government benefits right now. Residential Energy Services will then work with you to select the best energy-saving strategies for your home. We also collaborate with a trusted network of partners to verify that such measures are implemented correctly.

How do I apply for a cavity wall insulation grant?

Contacting Residential Energy Services is the fastest and most convenient way to determine if you qualify, assemble your qualifying criteria, and approach energy providers for cavity wall insulation grant assistance.

How much can I get from an ECO grant?

Free home energy efficiency upgrades are provided to qualifying households under the Great British Insulation Scheme and the ECO4 initiative. Grant funding is entirely conditional on establishing the best measure for your property at this point in time.

How much money is available for in ECO grants?

The Great British Insulation Scheme is projected to get £1 billion in funding. The ECO4 scheme, which is set to run through March 2026, is expected to deliver up to £4 billion in energy saving and heating improvements.

I already receive government funding; can I apply for an ECO grant?

If you already get help from the government through benefits, you might not be able to apply for the ECO4 scheme. You might still be able to get free insulation through the Great British Insulation Scheme.

Who pays for cavity wall insulation improvements to my home?

The Energy Company Obligation is a government programme that has energy companies pay for energy-saving improvements to your home that are carried out by approved installers.

Who decides what measures I’m suitable for?

Essentially, it’s up to the energy provider to decide which steps are best for your home. However, a home energy assessment from Residential Energy Services can make this process more accurate, relevant, and efficient, making sure you get exactly the help you need.

Cavity Wall Insulation Grant Eligibility

Am I eligible for a cavity wall insulation grant through ECO funding?

If you own your home or rent privately and your EPC grade is D or lower and you get one of the benefits that qualify for ECO4, you should be able to get help through either ECO4 or the Great British Insulation Scheme.

Is the ECO scheme means tested?

If you recieve government benefits based on your income, you might be eligible for the ECO scheme. Before you talk to your energy provider, make sure you are eligible.

What benefits do I need to receive to get ECO funding?

If you receive at least one of the following government benefits the energy company obligation should be able to support you with new energy efficiency measures:

  • Child Benefit
  • Pension Guarantee Credit
  • Income-related Employment and Support Allowance (ESA)
  • Income-based Jobseeker’s Allowance (JSA)
  • Income Support
  • Tax Credits (Child Tax Credits and Working Tax Credits)
  • Universal Credit
  • Housing benefit
  • Pension credit saving credit

I already receive ECO funding, can I apply for a new grant?

If you have previously received help from the government and your home qualifies, you may be able to get help through the Great British Insulation Scheme.

What EPC rating do I need to be eligible for ECO funding?

To qualify for ECO4 funding, your property must have an EPC rating of D, E, F or G. To qualify for funding under the Great British Insulation Scheme, your EPC rating must be D or below and your Council Tax Band A-D.

What tax bands are supported by the ECO scheme?

Through the Great British Insulation Scheme, households with low incomes in council tax bands A through D can get help.

I live in a rural area, am I eligible for ECO funding?

If you don’t live in an A-D tax band area but still have an EPC rating of D or lower, you may still be qualified for ECO support. Residential Energy Services can tell you if you are eligible.

Potential savings from Cavity Wall Insulation Grants


Is my home suitable for Cavity Wall Insulation?