Insulation Series: How KORE Fill Cavity Wall Insulation Is Installed

by Brian Flax | Aug 23, 2017

Typical cavity wall construction (brick outer leaf and block inner leaf)

Many homes in Ireland and across the UK are built using a cavity wall construction. This means that there is a gap or ‘cavity’ between the inner and outer leaf. Depending on when your home was built, this cavity could be filled with bonded bead cavity wall insulation, partial fill insulation, rigid insulation boards, foam and even blown mineral fibre. There are even many homes across Ireland that have no insulation at all.

Cavity wall construction was designed to assist with preventing rain water from crossing the external leaf to the inside of the house. Cavity walls helped stop penetrating dampness from wind-driven rain considerably, so while originally designed for homes in exposed western coasts, cavity wall construction quickly spread to drier areas of the country.

While some homes were insulated during construction, there is still a good portion of Ireland’s building stock that have no insulation between the walls at all. Fortunately, most cavity wall constructed houses can be retrofit with insulation with ease. In our latest blog post as part of the insulation series, we’ll take a look at how bonded bead cavity wall insulation, made from Expanded Polystyrene, is installed.

1. Determining if the property is suitable for cavity wall insulation

All existing buildings that are being considered for cavity wall insulation are inspected to BS 8208: Part 1:1985 Guide for the assessment of suitability of external cavity walls, for filling with thermal insulants – Existing traditional cavity construction, in addition to the KORE Fill installation manual and NSAI certification. All contractors that install KORE Fill Bonded Bead Cavity Wall Insulation must be KORE Approved to do so. We keep an active list of all approved CWI installers for reference on our website.

The use of a borescope to examine the existing cavity and inner faces of the masonry is mandatory and is a part of the on-site survey before any installation begins. This survey must find that:

  • A minimum cavity width of at least 40mm exists
  • There are no signs of dampness on the inner face of the cavity
  • All mortar joints are free from defects
  • Depending on the location of the home, the exposure of the building to wind-driven rain must be taken into consideration

All cavity wall insulation installers keep a detailed record of the on-site survey of the home. Any existing insulation material in the cavity must be in good condition and free from defects. Your installer will let you know if problems are found and any necessary repairs before installation can begin. There are other insulation system, such as external wall insulation and internal wall dry lining that can be used as an alternative if cavity wall insulation is found to be unsuitable.

2. On-site quality assurance of KORE Fill Bonded Bead

Quality assurance of the product is an essential part of installation that is performed on-site before any works begin. KORE require that all installers perform tests on the flow rate of both the bonded bead and the adhesive used. This testing ensures that the correct amount of bead and adhesive are mixed together during installation and that the product bonds correctly once inside the cavity. Flow rate tests are simple to perform and accurate, ensuring a high quality installation every time.


Testing the flow rate of bonded bead

3. Drilling patterns for installation

The next step in the process of installing cavity wall insulation is the drilling of holes in the exterior (outer leaf) of the home. The drilling pattern the installer will use is determined by the construction, the size of the house and any existing insulation. The installer will be able to show you the drilling pattern that will be used before any works begin, and examples of approved drilling patterns can be found in the KORE Fill NSAI Agrement Certificate.

The drill holes are about the size of a one-euro coin (22mm to 25mm), and are spaced out to ensure the cavity is filled completely with both bead and adhesive. All drill holes are completely filled at the end of installation and will closely match the existing colour.

If the house is a semi-detached or terraced property, the contractor will install a cavity wall brush between the properties to contain the bonded bead so that it does not affect the neighbouring property.


4. Installation of cavity wall insulation

Using compressed air, bonded bead and adhesive, the insulation is pumped into the wall cavity using specialised equipment through the drill holes. Installation starts with the drill holes beneath the ground floor windows and continues upward until the cavity is completely full. Most houses can be completed in just a few hours, depending on its size and the weather. In retrofit applications the product is pumped through the exterior of the home, causing far less disruption than other insulation systems. All required equipment and power will be provided by the installer, meaning you can sit back and enjoy a warmer home.


5. Post-installation checks and making good

After the product has been fully installed, the contractor will check to make sure there is no loose bead around any ventilation (wall vents, floor vents etc.), flues and around the ESB meter box. Before the drill holes are patched, you will clearly see the bonded bead installed in the cavity as seen below:


Once the product is successfully installed, the contractor will patch all drill holes to match the existing colour as closely as possible. In many cases you won’t be able to see the drill holes at all!


The contractor will complete the installation by making good on the rest of the property. This includes cleaning up all equipment, material and the product itself. In addition, you will be provided with a product and labour guarantee. The contractor will also show you how to use any products that were installed that require manual operation, like some wall ventilation products.

The KORE Fill Bonded Bead Cavity Wall Insulation System ensures that the function of the cavity is not impaired, meaning water will not be able to cross from the outer to inner leaf, while still being able to breathe. The bead and adhesive is water resistant, rot-proof and will last the entire lifetime of the house with minimal maintenance.

The benefits to choosing cavity wall insulation

The vast majority of houses built with a cavity wall construction are suitable for cavity wall insulation. The product is affordable, installation times are generally quick and the whole process causes minimal disruption to the home’s occupants. Once installed, you should notice a difference in how warm your home is and how well it retains heat, meaning you’ll run the heat less while staying warmer for longer periods of time. You should notice a reduction in your energy spend almost straight away, and the return on investment is generally short.

There are many grants and incentives for cavity wall insulation, including SEAI’s Better Energy Homes Scheme and the KORE Energy Efficiency Incentive with Electric Ireland. Some homeowners may even qualify for free insulation upgrades as part of the KORE Warmer Homes Scheme. If your home was built before 2006 your out of pocket costs for installing new cavity wall insulation could be significantly reduced. Learn more about the grants and incentives that may be available to you by clicking on the button below.