Cavity Wall Insulation Grants Explained

The two main insulation grant schemes available to applicants in the UK have different eligibility criteria. It’s important to understand the differences between the ECO4 and GBIS schemes to ensure you get the most out of your energy efficiency grant funding.

The fourth phase of the Energy Company Obligation (ECO) Scheme, ECO4 takes a whole-house approach to increase the energy efficiency of homes. Eligibility for the ECO4 scheme may include other heating measures as part of the grant application. Cavity wall insulation is compulsory as part of ECO4 if the home doesn’t have it already installed. ECO4 is the most generous grant scheme currently available, and Energy Saving Genie can check your eligibility in as little as 23 seconds. For more information on the ECO4 grant scheme, you can visit our dedicated ECO4 grant scheme page.

The Great British Insulation Scheme (formally called ECO+) can offer eligible applicants a single measure installation, where no other heating measures can be installed at the same time. This means that if you are eligible, cavity wall insulation can be installed, but no other insulation measure can be installed (e.g. loft insulation, external wall insulation or underfloor insulation). For more information please visit our dedicated GBIS page, or check your eligibility using our free grant checker.

What is Cavity Wall Insulation?

Exploring Cavity Wall Insulation

Not all homes have cavity wall insulation, as it only became common in houses built from the 1930s onwards (Prior to 1920, homes were mostly built with solid walls). If your house was built after the 1920s it is likely to have cavity walls, which is basically 2 separate walls with a gap in between. The outer wall is called the outer-leaf, and the inner wall is called the inner-leaf. The width of the gap is usually at least 40mm, however the width can vary depending on the property and how and when it was built.

A quick check to see if you have cavity walls is to check the outside of your building. If the bricks are all the same size and are laid lengthways, it’s likely that you have a cavity wall. If the brickwork is different sizes, this usually indicates that you have solid walls.

Even though cavity walls were common from the 1930’s, cavity wall insulation was only commonly installed in buildings from the 1990’s onwards. If your property was built between the 1930’s and 1990’s and hasn’t had cavity wall insulation installed, you could be eligible for a free cavity wall insulation grant.

Types of Cavity Wall Insulation Available

Cavity wall insulation material comes in three main types as follows:

• mineral wool – The original material, it first became popular in the 1950s. Mineral wool is created by heating and spinning igneous rocks into strands (similar to wool).
• polystyrene beads – Expanded polystyrene beads (EPS) are made of a carbon polymer that initially measure 0.5mm in diameter, but are then filled with air via a steaming process to increase their size to 3-5mm in diameter.
• ployurethane foam – Also known as PUR insulation, this heating technology has been available since the mid 80s and is present in newer buildings. It is a plastic carbon based formed into an inert polymer and is the highest energy rated insulator of all 3 materials

If you are eligible for a grant, a registered installer will determine the best option when they survey your property.

Understanding the importance of insulation

Insulation is an important energy saving measure to be installed, as it helps to trap heat inside your home in the winter months (as well as cool air in the summer). The energy saving trust estimates that about a third of all heat in an uninsulated home is lost through the walls. This means that your heating system needs to work harder to keep your home warm, increasing your costs and carbon footprint. Check your eligibility today for free cavity wall insulation using our free grant checker.

Why Install Cavity Wall Insulation?