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Cavity Wall Insulation

A Guide to Cavity Wall Insulation Grants in the UK

Are you a UK homeowner looking to slash your energy bills and make your home more comfortable? Cavity wall insulation might be the solution you need! This comprehensive guide will walk you through everything you need about cavity wall insulation and the government grants available to help you finance this energy-saving upgrade.

What is Cavity Wall Insulation?

Before we discuss the grants, let’s understand what cavity wall insulation is. Most houses built in the UK between 1920 and 1982 have cavity walls, consisting of two brick layers with a gap (cavity) in between. Cavity wall insulation fills this gap with insulating material, typically mineral wool, foam, or beads. This creates a barrier that prevents heat from escaping, keeping your home warmer in the winter and cooler in the summer.

Why is Cavity Wall Insulation Important?

Insulating your home is one of the most effective ways to reduce energy consumption, lower your carbon footprint, and save money on heating bills. According to the Energy Saving Trust, a staggering 35% of heat loss in an uninsulated home occurs through the walls. By insulating your cavity walls, you can significantly reduce this heat loss, making your home more energy-efficient and comfortable.

Government Schemes for Cavity Wall Insulation Grants

The UK government recognizes the importance of energy efficiency and offers financial assistance to homeowners through various schemes. Two primary schemes currently available for cavity wall insulation grants are:

The Great British Insulation Scheme (GBIS)

Launched in April 2023, the Great British Insulation Scheme (GBIS) replaced the previous ECO+ scheme. It aims to help low-income households and those living in energy-inefficient properties with fully or partially funded insulation measures. The scheme has a budget of £1 billion provided by the UK government and is delivered through large energy suppliers.

Eligibility for GBIS:

There are two main eligibility groups for the GBIS:

Low-Income Group:

You might qualify if you:

  • Own your home or rent privately
  • Have an Energy Performance Certificate (EPC) rating of D or below (E or below if renting)
  • Receive means-tested benefits
    • Child Benefit
    • Child Tax Credit
    • Income-Based Jobseekers Allowance
    • Income-Related Employment Support Allowance
    • Income Support
    • Pension Guarantee Credit
    • Universal Credit
    • Working Tax Credit
    • Housing Benefit
    • Pension Credit Savings Credit
  • Live in social housing with a household income below £31,000 a year and are vulnerable to living in cold conditions

General Group:

You might qualify if you:

  • Own your own home (unless in social housing)
  • Live in a property with a council tax band A-D in England, or A-E in Scotland and Wales
  • Have an EPC rating of D or below (E or below if in social housing)
  • You do not have to be claiming benefits

ECO4 Scheme

The ECO4 Scheme, launched in August 2022, takes a more holistic approach to home energy efficiency. It provides funding for various measures, including cavity wall insulation, boiler upgrades, and solar panels. With a budget of £4 billion (£1 billion per year), it is also delivered through large energy suppliers.

Eligibility for ECO4:

ECO4 has three eligibility groups:

Help to Heat Group:

To qualify, you must:

  • Own your home or rent privately
  • Be considered a low-income household
  • Have a home with an EPC rating of D or below
  • Receive at least one of the listed means-tested benefits
    • Child Benefit
    • Child Tax Credit
    • Income-Based Jobseekers Allowance
    • Income-Related Employment Support Allowance
    • Income Support
    • Pension Guarantee Credit
    • Universal Credit
    • Working Tax Credit
    • Housing Benefit
    • Pension Credit Savings Credit

Social Housing Group:

This group is specifically for residents of social housing. You might qualify if:

  • Your home is let below market rate
  • Your property has an EPC rating of D-G
  • Your home does not meet the Minimum Insulation Requirements
ECO Flex Group:

This group is for individuals who might not fit into the other categories. Eligibility is determined by Local Authorities based on localized criteria. This could include factors like:

  • Household income below £31,000 and an EPC rating of D-G
  • Vulnerability to living in a cold home due to health conditions

How to check your Energy Performance Certificate (EPC)

To check your eligibility for a cavity wall insulation grant, follow these steps:

  1. Access the EPC register online:
    • For properties in England and Wales, click here to access the EPC Register
    • For properties in Scotland, use the Scottish EPC register
  2. Enter your property’s postcode and select your address from the list provided.
  3. View and download your EPC report.

Once you have accessed your EPC, look for the following information:

Wall Construction and Insulation Status

Your EPC should indicate:

  • The type of walls your property has (cavity or solid)
  • Whether cavity walls have been previously filled

If your property has cavity walls that are not insulated, you may be eligible for a cavity wall insulation grant.

Check your Energy Efficiency Rating

Check your home’s current energy efficiency rating on your EPC, which ranges from A (most efficient) to G (least efficient). Properties with ratings of D to G may be eligible for support under schemes like the Great British Insulation Scheme

Check your properties Council tax Band

To check your council tax band for eligibility for a cavity wall insulation grant, follow these steps:

  • For properties in England and Wales, visit the official government website to check your council tax band
  • For properties in Scotland, click here to check your council tax band

Benefits of Cavity Wall Insulation

Investing in cavity wall insulation offers numerous benefits:

  • Reduce Energy Bills: Installing cavity wall insulation can lead to annual savings of £145 to £500 on your energy bills, depending on the size and type of your property.
  • Increase Comfort: Insulation eliminates cold spots and drafts, creating a consistently comfortable temperature throughout your home. It can also reduce noise pollution from outside.
  • Enhance Property Value: An energy-efficient home with a good EPC rating is more attractive to potential buyers, increasing its market value.
  • Shrink Carbon Footprint: Reducing energy consumption through insulation contributes to a smaller carbon footprint, helping to combat climate change. You can reduce your home’s CO2 emissions by up to 1300kg a year.
  • Low Maintenance: Cavity wall insulation requires minimal maintenance once installed.

If your property was constructed after 1930, it is probable that it has Cavity Walls, which are walls made up of two masonry walls with a minimum gap of 40mm between them. These walls can be identified by their brick pattern, called ‘stretcher bond,’ where all bricks are laid lengthways. Alternatively, their thickness, typically over 270mm, can also help identify them.

To insulate Cavity Walls, bonded polystyrene beads are injected by drilling a series of holes in the mortar joints of the external wall. Once the cavity is filled, the holes are made good and colour-matched as closely as possible to the original mortar. The insulation installation comes with a 20-year insurance-backed guarantee.

Cavity Wall Insulation can improve your energy performance certificate’s rating and save you money on heating bills, up to £150 per year, as well as providing better warmth during colder months. A Cavity Wall is one of the two walls required for Cavity Walls, which are walls built next to each other with a small gap of around 50mm between them.

  • More than one-third of the heat lost in an uninsulated home escapes through the walls.
  • Insulation saves you up to £275 per year on your energy bills.
  • Insulation helps keep your home warmer by preventing heat from escaping through the external walls.
  • Insulation helps reduce your carbon footprint by using less energy to heat your home.
  • Insulation is the number one recommendation on an Energy Performance Certificate (EPC) to improve energy efficiency.

To insulate your home’s cavity walls, the process usually takes about 2-3 hours, but it could take longer depending on your home’s size and accessibility. During the installation, the installer will drill small holes, about the size of a 10p coin, into the outside wall of your home and inject insulation into the wall cavity using special equipment. This process is done in a specific pattern to ensure complete coverage. Once the insulation is injected, the holes are filled with mortar to match the colour and texture of your home’s exterior. If your home has a pebbledash finish, pebbles are added to match the existing texture. After the installation, the holes are difficult to see, and your home will be more energy-efficient!

Insulation material reduces the amount of heat lost from walls by decreasing the transfer of heat outside the wall and reducing air circulation within the cavity walls.3 Around 35% of heat lost in a home is through its external walls.

You could save between £145 and £500 per year, depending on the property type and size. This is based on fuel prices from July 2023. Cavity wall insulation alone could save you up to £145 each year and reduce carbon emissions by up to 610kg. You could reduce your home’s carbon footprint by up to 1300kgCO2 a year.

 In most cases, yes, especially if you qualify under the low-income groups. However, you may have to contribute a portion of the cost, depending on the scheme and your circumstances. For instance, under the GBIS General Group, you may have to pay a portion of the cost based on your household income and the installation cost.

Your home is likely suitable if it meets these conditions:

  • External walls are unfilled cavity walls
  • The cavity is at least 5cm wide
  • Built before 1982 (or before 2005 in some cases)
  • Capable of heating efficiency in the long run  
  • Brickwork, outer wall, or masonry is in good condition
  • Low risk of flooding
  • Walls not exposed to excessive driving rain or extreme weather

Energy companies are obligated to fund energy efficiency improvements, like cavity wall insulation, under the Energy Company Obligation (ECO) scheme. They do this to meet government targets for reducing carbon emissions and avoid potential fines.