What is a cavity wall?
The external walls of most houses consist of two masonry (brick or block) walls, with a cavity gap of at least 50mm between them. Metal ties join the two walls together.
How is cavity wall insulation injected?
The cavity wall is injected with insulating material by drilling holes in the external wall through the mortar joints. Holes are generally between 22mm and 25mm in diameter and are 'made good' after injection, so they won't be too noticeable. Each hole is injected in turn, starting at the bottom.
How long does it take?
Cavity wall insulation normally takes around two hours to install, but the exact time depends on the size of the house plus other factors such as access.
Do I have to do anything before installation?
The drilling process creates some vibration, so it would be wise to remove ornaments, especially from external walls. The technician needs access to all walls of the house, so will need to get inside attached garages, lean-to sheds, conservatories, and so on. The installation can only really be effective if every wall is done. If you have a wall right on the boundary with a neighbour, you may like to tell them the technician will need to go on their property.
Is my house suitable?
Before the installation firm undertakes any work, they will undertake an assessment of your property to make sure it's suitable. This will be undertaken by a surveyor or the technician.
Is there much mess?
The drilling process will create a little dust, which will be cleared when the job's completed. It might be wise to remove vehicles from the drive and things close to the walls.
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 bristle brush. Of course, if your neighbour's house was to be insulated at the same time, the barrier would not be needed.
Does the technician have to come into my home?
The technician must undertake checks before and after installation, including any heating appliances, so it's essential that they have access inside the property. Apart from these checks, all work is carried out from the outside.
Are all systems of insulation the same?
There are several different types of insulation available. We have chosen InstaFibre White Glass Wool, Yellow Glass Wool, Rockwool, and InstaBead because they are all simple to install. Note: Glass Wool and Rockwool are often referred to as 'mineral wool'.
All systems of cavity wall insulation have been tested, assessed, and approved by the British Board of Agrement or the British Standards Insulation. All systems have a similar insulation value. Whichever system you decide on, you can be sure that the installer can offer a 25-year CIGA guarantee.
Are the technicians trained?
All technicians (team leaders) undergo training by the system 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 that 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 activates when the adjacent wall area. There is tolerance in the injection pattern so 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. He will also note the amount of material used, to know 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 stored 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 if they are already sleeved. If they are not, the technician will remove them and seal around them to prevent them from being blocked by the insulation. Other vents which may be redundant such as cavity vents or vents used to supply air to open fires in bedrooms might be closed off, and redundant airbricks may be filled. The technician should discuss this with you.
But my house has painted areas!
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 this with the installing firm.
What about filling the holes?
The technician will fill all the injection holes with mortar to match the existing mortar as closely as possible. He will use a mix which closely matches the existing colour and texture. On pebbledash finishes, he will apply pebbles to the surface to match the existing finish. After weathering, the holes are difficult to see.
If I am Concerned About the Installation, What Should I Do?
Talk to the installing firm and tell them 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.
Do I apply for the CIGA 25-year guarantee?
No, the installer or 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.
How long will the insulation last?
According to the British Board of Agrement, for the life of the building.
Will my house be warmer?
If your heating is not controlled by a thermostat, then yes. However, if you have a thermostat, it will maintain the heating at the same temperature, so you may not notice any difference. However, you should find that the temperature in some parts of the house improves, for example the small bedroom on the corner.
With cavity wall insulation, 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 any maintenance or servicing requirements?
No, not for the cavity wall insulation, but normal business maintenance is needed.
How much will I have to contribute towards the cost?
For cavity wall insulation and loft insulation up to 250mm, £149. Viscount will attract all grant funding directly from the utility. Surveys are carried out for free and without obligation, and the surveyors will always advise you on the best schemes available at their time of visit.
All prices are based on standard property sizes (extra charges may apply for non-standard property sizes). The final depth of loft insulation is required to be 250mm. All prices are for gas-heated properties, and further discounts apply for electric or coal-heated properties - please ask for details.
How do I claim the grant available towards the cost of insulation?
You don't have to claim the grant, we do that for you. All you have to do is pay the customer's contribution and we will receive the grant monies directly from the utilities.