As energy bills have risen steadily (and in some cases sharply) in the past 5 years, homeowners and renters alike are on a mission to reduce their energy outgoings. A popular way to achieve this for those living in properties that are over twenty years old, is to install Cavity Wall Insulation.
What is Cavity Wall Insulation, how much does it cost to install and how quickly can you expect to experience the financial and practical benefits? Get the lowdown on Cavity Wall Insulation and whether it’s right for your property.
What is Cavity Wall Insulation?
Cavity Wall Insulation adds another layer of insulation to a property by injecting insulation into the cavity between your property’s inside and outside walls to fill the gap and stop warm air escaping.
Insulation is inserted into the cavity by drilling 22mm holes into the outside wall and then closing these holes with cement.
This process must be done professionally as it uses specialist equipment and usually takes about 2 hours to complete.If your home is between 20-100 years old, and if your external walls are at least 270mm thick, your property will usually be constructed in a way that makes Cavity Wall Insulation an appropriate insulation method.
What are the benefits of Cavity Wall Insulation?
· Reduces energy bills (up to £400 a year in some homes)
· Traps more heat within your property
· Can be fitted quickly and easily
· Ideal for homes built after the 1920s that have a cavity in the walls
· Benefits of insulation can be felt quickly
· Insulation keeps home warmer in winter and cooler in the summer
· Low maintenance
What are the disadvantages of Cavity Wall Insulation?
It’s sometimes installed on the wrong properties
Cavity Wall Insulation is largely effective if used on the right kind of property. Properties with a large cavity wall (more than 40mm with a height of less than 12 metres) are suitable for this kind of insulation.
It’s installed in wet and windy areas of the UK
Don’t install Cavity Wall Insulation if you’re located in an area of the UK that’s exposed to excessive ‘wind-driven’ rain. The South and North West of England, along with the west coast of Wales get a lot of wet and windy weather throughout the year and these conditions will weather brickwork quickly, and cause moisture to reach your insulation, resulting in a damp problem. If you live in these areas, it’s best to research alternative ways of further insulating your home.
Can lead to ventilation issues
Although the cavity wall will conveniently trap warm air in your property, air flow around your property has now changed and adequate ventilation is still needed in order to prevent mould and dampness. Ventilation must be considered during the installation of Cavity Wall Insulation to prevent these kinds of problems from happening in future.
What are the different types of Cavity Wall Insulation?
· Polystyrene beads
· Expanding foam
· Mineral wool
· Cavity batts (pre-cut slabs of insulation typically used in new buildings)
How do I know if my property already has Cavity Wall Insulation?
If your property was built within the last twenty years, it likely already has Cavity Wall Insulation. To make sure, you can instruct a specialist to check with a borescope inspection. This consists of a small 12mm hole that is drilled into your external wall. A camera is then inserted into the hole to see if the walls are hollow or not.
Alternatively, you can check with your local authority’s building control department. You can get in touch via your local council’s website, searching the term ‘building control’.
How much does it cost to install?
Depending on the size of your property and the type of insulation you choose, Cavity Wall Insulation can cost up to £4,600. At the time of writing, the Energy Saving Trust estimates that installation for a detached house can cost £4,600, £2,700 for a semi-detached house, £2,100 for a detached bungalow and £1,500 for a mid-terraced house (these figures will be subject to change).
Can I get a government grant to help me with the cost of installing Cavity Wall Insulation?
You could get financial help from the government to install Cavity Wall Insulation. There is a government-funded energy scheme called The Great British Insulation Scheme that can contribute to —or fully pay— for your insulation. This funding is available to households in England, Wales and Scotland.
Your property will be eligible for Cavity Wall Insulation if:
✔ External walls are unfilled
✔ Your home is not at risk of flooding
✔ Your external wall’s cavity is at least 50mm wide and doesn’t contain rubble or debris
✔ Your property’s brickwork is in good condition
✔ You don’t live in an area that regularly experiences heavy wind and rain
You’ll be eligible for financial help towards Cavity Wall Insulation if your property is in Council Tax Band A-D (England) or A-E (Scotland or Wales), or your property has an Energy Performance Certificate (EPC) rating of D or lower. You are also eligible if you or people living in your household receive certain benefits. Read more about The Great British Insulation Scheme, its eligibility criteria and how to apply
How long does Cavity Wall Insulation last for?
The longevity of Cavity Wall Insulation will depend on the weather conditions your property is exposed to, the type of insulation used and how it was installed. It should last a minimum of 25 years, if installed by an installation company registered with the Cavity Insulation Guarantee Agency (CIGA).
Some insulation can be defective but it’s possible to extract the faulty insulation and fill the cavity again with more suitable insulation that is better at keeping heat in.
Where can I get a list of recommended installers for Cavity Wall Insulation?
The Cavity Wall Insulation Guarantee Agency (CIGA) provide a list of recommended installers and you should be able to find one local to you. Installers listed are registered with the The Installation Assurance Authority and their work will follow building regulations. This means that if you were to experience any problems with work installed by a CIGA-approved installer, these problems would be solved promptly for you by CIGA.
Key Takeaways: What is Cavity Wall Insulation and Is It Right For My Property?
Cavity Wall Insulation is a quick and mess-free way of retrospectively insulating the cavity between your property’s inner and outer walls, and should last for 25 years.
If your house is between 20-100 years old, your walls’ cavities are at least 50mm wide, your property’s brickwork is in good condition, your home is not at risk of flooding and you don’t live in an area that regularly experiences heavy wind and rain, you could quickly feel the benefits of Cavity Wall Insulation.
This kind of insulation is relatively low maintenance and helps to keep your property cooler in summer as well as warmer in winter.
Insulation can cost up to £4,600 for a detached property, less for semi-detached properties and terraced houses (stated figures above correct at the time of writing but will be subject to change and dependent on location).
Consider if additional ventilation measures are needed when installing Cavity Wall Insulation to prevent damp and mould problems.
There are 4 different types of Cavity Wall Insulation; polystyrene beads; expanding foam, mineral wool and cavity batts (pre-cut slabs of insulation).
You can check whether you already have Cavity Wall Insulation by requesting a borescope inspection from a specialist. Or you can ask your local authority’s building control department, who may have records of recent improvements.
You could be eligible for help towards the cost of insulation installation. Read our article on The Great British Insulation Scheme and its eligibility criteria
You can view a list of approved installers who are recommended by the Cavity Wall Insulation Guarantee Agency (CIGA). These installers are registered with The Installation Assurance Authority and their work will meet building regulations. If you experience issues with the installation in future, any problems should be rectified promptly by CIGA.
For more information on how Cavity Wall Insulation can be used as part of a range of methods to make your home more energy efficient, get in touch with our specialist team of energy advisors today.