Insulation, Solar Panels, Heat Pumps and Wind Turbines From Mark Group

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 airgap 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 silicants 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 Agrément 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 airbricks 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 effects them.

On pebbledash 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 Agrément say so.

What are the benefits of loft insulation?

Having the correct depth of insulation can save you between £60 – £205 a year on your heating bills depending on existing levels of insulation.

You will reduce the carbon footprint of your house by up to 1 tonne per year – when you consider the average household emits around 6 tonnes per year, that’s no small saving (Source: Energy Saving Trust January 09).

Improving the energy rating of your home on an Energy Performance Certificate is another advantage loft insulation brings.

What is loft insulation?

Loft insulation is man-made mineral fibre in a roll form. Often referred to as “Quilt” the material generally used is made from silica and, creating a wool-type product also known as glass wool.

Old style loft insulation was known to be itchy, but modern insulation has been re-designed to be soft to touch and virtually non-itchy.

Regardless though, it will be delivered into your loft sealed inside a plastic package.

How is loft insulation installed?

The insulation is simply laid between and across the joists. The loft hatch will also be insulated.

We must stress that once we have finished, the joists will not be visible and we recommend that you do not access the loft without the use of crawling boards and only still if you are aware of the exact position of the joists.

What is the procedure regarding boarded areas?

If you have a boarded loft we may still be able to proceed with the insulation depending upon the survey results.

Standard industry best practice is for the insulation to be laid over the boards.

What happens to items stored within the loft space?

You must ensure that items stored within the loft space are removed prior to our crews arriving.

Small items such as Christmas trees and suitcases will be moved within the loft by our crews, but our technicians are not able to move either general or large amounts of items.

Please ask if you are unsure.

How long does it take?

The installation should take between 1-2 hours to complete.

Do I need to provide anything?

No, our installation teams provide all of their own equipment including lights and ladders.

Is there much mess?

No, a small amount of dust may fall from the loft hatch, (depending how long it has been since the hatch was last opened) which will be cleared by the crew and all packaging will be removed from your home.

How long does loft insulation last?

Providing the material is left undisturbed, it is maintenance free and should last indefinitely.

What is solar electricity?

Solar Electricity, otherwise known as Solar Photovoltaic (Solar PV) uses energy from the sun to create electricity that can be used to run appliances, such as computers, washing machines and kettles.

A Solar PV system simply requires daylight to generate electricity and so still generates power on a cloudy day.

There are three main components in a Solar PV system:

• Solar PV Panels – that use the energy from the sun’s rays to create electricity.
• Inverter – which converts the electricity produced from direct current (DC) to alternating current (AC) (240V). AC 240v electricity is the same form of electricity as that supplied by the mains power grid.

• System connections – which include simple cabling, safety switches and a display to monitor the system.