Cavity wall insulation
Most homes built after around 1920 onwards are likely to have cavity walls, meaning that its external walls are made of two layers with a small gap or `cavity' between them. This cavity can be filled with an insulating material, generally blown fibre, to help you save on the heat which escapes through them. It's generally thought that around 30-35% of all heat loss from homes occurs through the external walls.
As well as keeping the warmth exactly where need it's needed - indoors, cavity wall insulation can also help to reduce condensation on external walls, by keeping the inner layer warmer than it would be otherwise.
And in addition to helping you to heat your home more efficiently and therefore reducing the money you spend on heating, you'll help to reduce carbon dioxide emissions - one of the biggest causes of climate change, with homes being amongst the worst offenders. If every UK household that is suitable for cavity wall insulation installed it, we could save around 4 million tonnes of CO2 every year. That's around 4 billion kilograms, or 8.8 billion pounds.
Cavity wall insulation is so cost effective that it has been described as a 'no brainer', by a spokesman for the Energy Savings Trust. It will pay for itself over and over again. It makes perfect sense that the better insulated your home, the less energy you need to keep it warm - and the more money you'll save, whilst helping to fight climate change of course.
There are grants and offers available to help pay for blown fibre cavity wall insulation, up to 50% for those considered 'Able To Pay' and 100% for the more vulnerable 'Priority Groups', such as those on benefits, the elderly and the disabled.
To be suitable for cavity wall insulation, your home should currently have unfilled cavity walls, a cavity of at least 50mm and with the masonry/brick work in good condition. Some walls exposed to driving rain and those with narrower cavities can be unsuitable for blown fibre cavity wall insulation, though bead insulation or solid wall insulation might be suitable in those cases. However, bead insulation and solid wall insulation does not currently attract grant funding.
To check whether or not your property has suitable cavities, take a look at the diagrams below.
If the brickwork has been covered with external render and internal plaster, so that you cannot see the brick pattern, you can also check if it's likely to be a cavity wall by measuring its width. Go to a window or door on one of your external walls, and take a measurement from the inside plane of the interior wall to the outside plane of the external wall. If the measurement is more than 260mm deep then it probably has a cavity; a much narrower wall would suggest that it does not.
As stated above, blown fibre insulation attracts a grant. Unfortunately, if your property is unsuitable for blown fibre insulation and you have to opt for bead insulation or solid wall insulation, then you will not receive grant assistance. However, insulating still makes sense, it will help reduce your bills and will eventually pay for itself, if not as quickly as with grant funding of course. With fuel bills unlikely to stay low forever, it makes sense to save on heating your home as early as possible.
Thinking of DIY?
Filling cavity walls is not suitable for DIY, it takes specialised equipment to install it. In addition, to attract any grant funding, as well as to ensure the work is carried out correctly - and guaranteed, installation must always be carried out by a registered installer. A registered installer for cavity wall insulation is considered to be one which is a member of one or more of the following organisations:
The National Insulation Association (NIA), to which installers sign up to a code of professional practice.
The Cavity Insulation Guarantee Agency (CIGA), who guarantee the installation for 25 years.
The British Board of Agrement (BBA)
With professional installers doing the work, your home will generally take around two hours to insulate. This does depend on the size of your property and how accessible its external cavity walls are of course. Once the fibre has been blown in, through small holes drilled into the cement between the brick, the installers will plug the holes with fresh cement of a suitable colour, to match the existing mortar, leaving no mess and nothing more for you to do except to turn down the thermostat by a few degrees.
Well, no, that's not true really, is it? It's the image which tends to be shown, but if you did that, your home would actually be colder! In reality, your heating will simply need to work less hard to keep the temperature at the same level and the temperature fluctuations should even out more.
See our Grants & initiatives page.
