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  • Cost of Cavity Wall Insulation

    Insulation prices for cavity walls.

    Average cost of supplying and fitting cavity wall insulation is

    This type of job normally takes around 3 hours to complete


    It was standard practice for some time that homes were built with double walls, using a cavity between them to prevent rain penetrating from the outside and to provide some insulation. However, it has long been known that unfilled wall cavities will let heat escape from the inside, therefore, placing increased demand on your heating system, which means higher energy bills. Organisations such as The Energy Saving Trust estimate around 35% of heat loss from homes can be through cavity walls which are not insulated. Installing cavity wall insulation is a reliable way and fairly cheap way to make your home warmer and save you money on heating bills. Cavity wall insulation simply means filling the cavity with an insulating material, usually some sort of foam which is pumped through holes which are drilled in the external wall.

    Most homes are suitable for cavity wall insulation as long as they have empty cavity walls with masonry or brickwork in good condition and you are not currently experiencing any damp problems. The great thing about cavity wall insulation is that there are often grants available to cover most, if not all the cost of the installation. But to benefit from any grants, you need to choose an insulation installer who is a member of the National Insulation Association, the Cavity Insulation Guarantee Agency or the British Board of Agrément. You can use MyJobQuote to find a reliable, local installer, simply enter brief details about your home and give contact information, then you will have up to three tradesmen or companies getting in touch to provide advice and quotations.

    Average cavity wall insulation prices

    Job Description Duration Material Cost Labour Cost
    Detached bungalow install cavity wall insulation 3 hours £150 £280
    Flat install cavity wall insulation 2 hours £100 £230
    Mid-terrace house install cavity wall insulation 2-3 hours £250 £125
    Detached house install cavity wall insulation 4 hours £500 £200

    Things to consider about cavity wall insulation

    Not all homes are suitable for cavity wall insulation, you need to have a survey conducted first before you know if having cavity wall insulation installed is appropriate or not. Walls which are exposed to the heavy wind-driven rain, may not be suitable for insulation and best left as a cavity to avoid damp problems, especially if insulated using mineral wool or similar. The costs for cavity wall insulation depend on the size of your house and the insulating material used, but there may be grants available which may cover the cost of the insulation or at least part of it. The recognised trade bodies for the cavity wall insulation industry are the National Insulation Association, the Cavity Insulation Guarantee Agency and the British Board of Agrément. Free cavity wall insulation, or grants towards it, are available from some energy suppliers under the Energy Company Obligation (ECO) scheme.

    The ECO scheme means large gas and electricity suppliers such as British Gas, EDF Energy, and Scottish Power – are obliged to help households with energy efficiency measures to save money on their energy bills and reduce carbon emissions. The Energy Company Obligation aims to cut carbon emissions and reduce fuel poverty across the UK with over £1.3billion spent on energy efficiency and heating measures each year. Installation of cavity wall insulation is usually done by a local contractor and it can be complicated to work out if you’re eligible for ECO funding or not, it really all depends on your home and if you receive any benefits. But even if you are not on benefits, you may still be eligible for help with insulation if you’re a social housing tenant in a home with a low energy efficiency rating.

    Until quite recently, pretty much everyone was entitled to a grant for cavity wall insulation. However in 2016, a few things changed, specifically, the rates the cavity wall installers are paid per tonne of carbon saved have dropped. It is now for a house to get 100% funding for cavity wall insulation, most will have to make some contribution which will be entirely dependent on the energy performance certificate (EPC) of the property which will be carried out by a qualified energy assessor, normally paid for by the cavity wall installer.

    Doing it Yourself

    Cavity wall insulation is the process of injecting an insulating material into the gap between the walls. There are a variety of different types of insulating materials you can choose from, but they all work in the same way. If you have the right equipment, injecting cavity wall insulation is pretty straightforward. Small holes which are drilled between the bricks on the outer wall, then the insulating material is injected through the wall until it fills the cavity. Then the holes are filled in to match the brickwork as closely as possible. But before you decide to insulate the cavity, you should have the walls checked for damp and ensure that the damp proof course is intact all around the house. In addition, the brickwork all has to in good condition, if not, the wall will need to be repointed prior to any cavity insulation.

    All essential ventilation openings including flues and air bricks in the cavity wall must also be checked and the installation should not proceed until these ventilation openings have been sleeved or otherwise modified to prevent then getting blocked up by the insulating material. The materials used to fill the cavity should be either Mineral Wool, Urea Formaldehyde Foam, or Expanded Polystyrene Beads. But remember, that if your cavity wall insulation is carried out as DIY job, it is unlikely you will be able to claim any grants toward the costs, so you need to do your sums very carefully to ensure the job would not be even cheaper if you hired a professional installer to do it for you with a grant! Las

    Cavity wall checklist

    • If your home was built between 1920 and 1990, it’s likely to have cavity walls with no insulation
    • Walls regularly exposed to wind-driven rain are not suitable for cavity-wall insulation
    • You need a registered installer to fit cavity wall insulation
    • Cavity wall insulation is one of the most cost energy efficiency effective measures


    How much can I save per year with cavity wall insulation?
    This will obviously depend on many factors, but typically for a detached house, you can potentially save up to £275 per year, whereas with a smaller mid-terrace house you could save around £105 per year. A flat will be even less with around £80 annual savings.
    Are there any potential problems with cavity wall insulation?
    Some homeowners do report damp problems after cavity wall insulation. This is likely because damp problems have been missed during the pre-installation inspection, as houses with damp should have cavity wall insulation installed, filling the cavity will only make the damp worse! So all pre-existing moisture problems have to be resolved before cavity wall insulation. A professional cavity insulation contractor should be able to advise you on whether your walls are suitable for insulation or not.
    Do I need wall insulation?
    If you live in a modern property built after the 1990's, probably not as your walls were likely insulated at the time of building. But with an older property that has cavity walls, you probably do need the insulation.
    Do I need planning permission for cavity wall insulation?
    No, you don’t normally need planning permission unless you live in a listed building or in a conservation area, but always check with your local authority before having any work carried out.
    Can I get financial help with the installation?
    Probably, there are many energy companies offering grants towards the cost of cavity wall insulation, you need to check with cavity wall installers in your area to see if you are eligible.
    Last updated by MyJobQuote on 7th May 2019.

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