Cavity Wall Insulation Frequently Asked Questions

Cavity Wall Insulation Frequently Asked Questions

What is a cavity wall?

Most modern homes are generally constructed of two masonry walls (brick or block), with at least a 50mm air gap or ‘cavity’ in between them.

What is cavity wall insulation? 

Most people are aware of what loft insulation looks like. It is generally a mineral wool made out of either glass or rock fibres and is packaged into a roll. This is laid out like a quilt into the loft space. Cavity wall insulation is a similar product, made in the same manufacturing plants, within the UK, as loft insulation, but is specially treated with silicates and milled down in order for it to be blown into the cavity of your home. It therefore creates the same quilt-like effect as loft insulation but in the enclosed void around your home.

How will the cavity wall insulation be installed? 

Our technicians will arrive at your home and perform a pre-installation check. Remember to ask them for their identification cards. The installation process is essentially in two parts. Firstly, the technician will drill holes in the mortar in-between the bricks of your home, at specific points around each elevation. These holes will be of 22mm to 25mm in diameter.

The insulation will then be injected into the holes from the outside (via the machine in the van) taking between two to three hours (for a three bedroom semi-detached house).

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 safety and peace of mind. The technician will need to gain access to all walls, so he will need to get inside attached garages, lean-to-sheds, conservatories etc. If you have a wall right on a 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 into the house?
The technician must undertake checks before and after installation, including any heating appliances, so it is essential that they have access inside the property.

Is there much mess? 

The drilling process inevitably creates a little dust. The technician will go around the outside of your home at the end of the installation and clean up. It is important to note however, the conditions and nature of our weather can at times hamper even the most determined attempts. Please, take the time to speak with our staff and be sure that you are happy with the finished product. We also believe it wise to remove vehicles from the drive and items close to the walls. In return this will give the technician better access for equipment and tools.

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

We also believe it wise to remove vehicles from the drive and items close to the walls. In return this will give the technician better access for equipment and tools. This is usually a length of bristle brush. If the neighbour’s house were to be insulated at the same time, or has already been insulated, the cavity barrier will not be needed.

How do I know the walls are full? 

This system of cavity wall insulation has a defined pattern of holes, which has been tested by the British Board of Agreement to verify that it results in a complete fill. Also, during your survey, we took measurements of your home including a depth gauge and inspection of the cavity to be filled. From these measurements we know the amount of material required to correctly fill your walls.

The technician will, therefore, check and record this data and match this against the quantity of insulation used. Our internal office staff operate a 100% check of this data and measure your results before we issue your 25-year guarantee. It is possible that you may also be randomly selected in our on-site technical monitoring.

What about the ventilators that are in the external 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 are in bedrooms may be closed off. The technician should discuss these with you, so if you have any questions please ask. Redundant air bricks may be filled.

What about filling the holes? 

The technician will fill all the injection holes with mortar that closely matches the existing colour and texture.
On some older properties or weathered facades it may take several months for the newness of the mortar to blend, but these holes are very small and they will blend as the weather affects them. On pebble dash finishes, they will apply pebbles to the surface to match the existing finish, as close as possible.

But my house has painted areas? 

Normally, we 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.

When will I receive the guarantee? 

The guarantee you will receive is called a “CIGA” (Cavity Insulation Guarantee Agency) which guarantees workmanship and materials for 25 years. We will apply for it on your behalf and it will be sent to you direct from CIGA. It can take up to 8 weeks for this to be delivered to you after installation.

Will my house be warmer? 

Insulation dramatically reduces heat loss through the insulated wall therefore you will be able to achieve the same temperature in your home by turning your thermostat down by a little. Your property should still achieve the desired warmth because the house will retain its temperature for longer. It can also be noted that during the summer the insulated cavity will prevent some of the suns’ heat from entering the walls, therefore, keeping your home cooler.

Are there any maintenance or servicing requirements? 

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

If I am concerned after the installation – what should I do? 

Talk to us to discuss your concerns and allow us an opportunity to investigate your worries. Most concerns can be resolved swiftly and efficiently so please do not hesitate to speak to a member of our customer services team.

How long will the insulation last? 

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

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