Cavity Wall Insulation

It is estimated that 35% of all heat loss from an uninsulated home is through the walls. This makes cavity wall insulation one of the most cost-effective solutions you can take to start saving money on those heating bills.

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Cavity Wall Insulation

Cavity wall insulation is used to reduce heat loss from homes by filling the air space between walls and preventing the transfer of heat, keeping your home warm in the winter and cool in the summer. This means that, in the long run, cavity wall insulation can help to save you money on your energy bills, balancing out the cost of cavity wall insulation and saving you more in turn. As part of our cavity wall insulation installation service, our qualified surveyors will come and survey your home to calculate your possible savings and explain the benefits of home insulation.

There are various types of cavity wall insulation available, ranging from wool to foam. The type of cavity wall insulation required will depend on your home and the space available. Our experienced and friendly cavity wall insulation installers will assess the space and advise you on the best option. With over 30 years of experience in cavity wall insulation installation, we have answered a wide range of frequently asked question in relation to cavity wall insulation. We have collected the most popular questions asked to help you understand what cavity wall insulation is, the price of cavity wall insulation, and our cavity wall insulation process.

How does it work?

Most homes built after the 1930s are built with two exterior walls with an unfilled cavity in between. By filling this empty cavity with wool insulation the warmth from the home is prevented from passing through, acting like a blanket and bouncing it back into the house.

In this same way, it can help to keep your home cool in the summer by stopping the heat from outside from transferring into your home.

Are my walls suitable for Cavity Wall Insulation?

The type of insulation you need depends on whether you have a cavity or solid wall. If your home was built after the 1930’s it is likely to have cavity walls. The good news is it’s easy to tell based on the pattern of your bricks. If your bricks have an alternate pattern of long and short bricks your wall is likely solid and therefore no available for insulation. However, if it has an even brick pattern it is likely to have a cavity.

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Cavity Wall Insulation Installation Process

To insulate your cavity walls, we drill small holes up to 26mm in diameter at intervals of around 1m on the outside wall of your home in a specific drill pattern. With specially designed equipment, we then blow insulation into the cavity. Once all the insulation is in, we fill the holes in the mortar joint, so you’ll barely notice them. You will also receive a 25-year CIGA Guarantee.

Filling cavity walls is not a job you can do yourself: you need to be a registered installer. We can do the job in around two hours for an average house with easily accessible walls; it is simple and quick. At the end of the installation, Heat Insulation Ltd will apply for your independent 25 years C.I.G.A. Guarantee to ensure, in the unlikely event of a problem, any issues will be rectified quickly and easily.

Will I benefit from Cavity Wall Insulation?

If your home was built after 1930, the chances are that its external walls are made of two layers with a gap or cavity between them. Cavity wall insulation fills that gap, keeping the warmth in to save energy.

Your home will usually be suitable for cavity wall insulation if:

    • Its external walls are unfilled cavity walls
    • Your cavity is at least 40mm wide
    • The masonry or brickwork of your property is in good condition
    • It is more than ten years old (most newer houses will have insulation already).

Will it cost me?

With current government and local schemes, funding is available for those claiming benefits. If you fit the funding criteria then you won’t have to pay a penny for your cavity wall insulation.

If you are a landlord, own or privately rent your property apply for a free survey from our trained installers.

Finance and one-time payment options are available for those who don’t meet funding criteria.

Impact on the Environment

The UK’s 21 Million domestic dwellings are responsible for as much as 27% of the countries CO2 emissions. With as much as 35% of the energy being saved through cavity wall insulation on the average house, the right insulation could have a huge impact on UK carbon emissions.

All new builds are being built with cavity wall insulation as standard, showing the commitment the industry is giving to this energy-saving measure. Cavity wall insulation is not just good for the bank balance, as it also plays a big part in reducing our carbon footprint.

How to tell if my walls are already insulated

If you struggle to heat your home despite high heating bills, this is a good sign your walls are not insulated. However, if you want a more scientific method you can always use a thermal imaging camera.

It is always best to call on professional services to establish your insulation requirements. If you decide to go ahead with it this is not something you can do yourself so accredited installers are required to carry out the process from survey to completion or you cannot access any grants or guarantees. If you have any damp patches on your internal walls, then they should not be insulated until the problem is sorted out. You should speak to a builder who specialises in damp prevention.

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How much will I save?

You could save up to £250 a year on heating bills alone, giving you a payback within just 5 years. Include the benefits of a comfortable home and the impact on the environment cavity wall insulation becomes an easy choice.

Everything you need to know

Here you will find a list of commonly asked questions in relation to Cavity Wall Insulation.

What is Wall Cavity Insulation?

The external wall of a house is constructed of two masonry (brick or block) walls, with a cavity (gap) of at least 50mm between. Metal ties join the two walls together.

How is cavity wall insulation installed?

The cavity wall is injected with insulating material by drilling holes in the external wall, through the mortar joint. Holes are generally of 22-25mm diameter and are ‘made good’ after injection. each hole is injected in turn, starting from the bottom.

How long does it take?

Cavity wall insulation normally takes around two hours to install, but the time does depend on the size of the house and other factors, such as access

Is my house suitable?

Before the installation, the installing firm will undertake an assessment of your property to confirm that it is suitable for insulation. This assessment may be undertaken by a surveyor of the technician before installation.

Do I have to do anything before the installation?

The drilling process does create some vibration – so it would be wise to remove ornaments, particularly on external walls, for their safety and your peace of mind. The technician will need access to the walls, so they will need to get inside attached garages, lean-to sheds, conservatories etc. The insulation can only be really effective if all walls are done. If you have a wall right on your boundary, you may like to mention to your neighbour, that the technician will need to go onto their property.

Does the technician have to come inside the house?

The technician must undertake checks before and after installation, including any heating appliances, so it is essential that they have access to the property.

My house is semi-detached, how do they stop insulation going into my neighbour’s cavity?

Assuming your neighbour’s house is not already insulated, the technician will insert a cavity barrier at the party wall line. this is usually a length of a bristle brush. Of course, if the neighbour’s house were to be insulated at the same time, the cavity barrier would not be needed.

Are all the systems of insulation the same?

There are several different types of insulation: – Bonded bead (white polystyrene beads) – Glass wool (yellow or white in colour) – Rock wool (grey/brown in colour) – Urea formaldehyde foam (white foam) Note: both glass wool and rock wool are known as ‘mineral wool’. All systems of CWI have been tested, assessed and approved by the British Board of Agrement or the British Standards Institution. All are suitable for their purpose. Except for Urea Formaldehyde foam, the systems can be used in all parts of the UK. All systems have a similar insulation value.

Are all technicians trained?

All technicians (team leaders) undergo training by the systems supplier and the installing firm to ensure they are competent in CWI and carry a training card. Please feel free to ask to see the training card.

How do I know the walls are full?

Each system has a defined pattern of holes, which has been tested to verify that it results in a complete fill. Most systems have an automatic cut out, which actuates when the adjacent wall area is full. There is tolerance in the injection pattern so that the material will flow past the next injection hole.

Is the insulation dense?

No, as the insulation is contained within a masonry wall, it doesn’t need to be ‘dense’. For insulation and other purposes, a light density is better. Before installation, the technician will undertake a quality test to ensure the insulation will go into the wall at the right density. They will also monitor the amount of material used for the size of your property to ensure that sufficient insulation has been installed. Note: drilling a hole in the outer wall and testing the cavity fill with a rod or pencil will not provide any meaningful information.

What about the ventilators that are in the internal wall?

Ventilators supplying combustion air to fuel burning appliances must be safeguarded. Similarly ventilators at ground level that ventilate below timber floors must be safeguarded. The technician will investigate them to check they are already sleeved. If they are not, the technician will remove them and seal around them to stop them being blocked by the insulation. Other vents, which may be redundant, such as cavity vents or vents that used to supply air to open fires in bedrooms may be closed off. The technician should discuss these with you. Redundant air-bricks may be filled.

What about filling holes?

The technician will fill all the injection holes with mortar to match the existing as closely as possible. They will user a mix that closely matches the existing colour and texture. On pebbledash finishes, they will apply pebbles to the surface to match the existing finish. After weathering, the holes are difficult to see.

What if my house is painted?

Normally, the installing firm will not paint the injection holes. Unfortunately, even if the original paint is used, it may not match due to weathering. So it may be necessary for you to consider painting the area, after the mortar has dried. You should discuss and agree what will be done, with the installing firm.

Do I apply for the CIGA 25 year guarantee?

No, the installer or the agent submits the guarantee application. The guarantee is posted to you within days of the application being received at CIGA – KEEP IT SAFE. CIGA is non-profit distributing; its only function, is to stand as guarantor for the promises set out in the guarantee. It has the resources to meet the promises made in the guarantee. All professional approved installing firms are members of CIGA and can apply for a CIGA guarantee, for properties built with traditional cavity walls. You should insist on a CIGA guarantee, since nothing else can give you the level of assurance to which you are entitled.

Will my house be warmer?

Yes – if your heating is not controlled by a thermostat. However, if you have a thermostat, it will cut out the heating at the same temperature, so you may not notice the difference in the room with the thermostat. However, you should find that the temperature in other parts of your house improves, for example, the small bedroom on the corner. With CWI, you should find that the house holds its temperature for longer, therefore the time between heating cycles may be longer. The result should be a more even temperature throughout the house and/or a reduced fuel bill.

Are there are servicing or maintenance requirements?

No, not to the cavity wall insulation, but normal building maintenance is needed.

How long will the insulation last?

For the life of the building – the British Board of Agreement say so.

If I'm concerned after the installation what should I do?

Talk to the installing firm and tell them of your worries. A contract exists between you and the installer, so they must be given the opportunity to investigate your worries. They will help you.

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Crowle Street, Hull, HU9 1RH

01482 588591