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Costs for Cavity Wall Insulation

Material Costs, Labour Fees and Time Frame Estimates for Cavity Wall Insulation

When it comes to injecting insulation to your cavity wall, expect the costs to come up to about £500, although quote estimates will likely range around £400 to £700. Costs will generally vary based on the size of the property, its location and overall accessibility. Larger properties will take longer for the job to get completed and this will reflect on the overall costs. This would, however, reflect on a price drop for every square metre. 

If your property has numerous external walls that are beyond the 2 to 4 average, expect the costs to be higher. Additional costs will also be added if the job will require scaffolding. 

Cost Breakdown

If you have a semi-detached property with 2-storeys that you wish to install cavity insulation to, expect the costs to be around £500. Of that, £300 covers the equipment and material costs and £200 pays for the services of the tradesmen. 

Time Frames and Labour Costs

It’s more common for specialists in cavity insulation to charge based on the job size instead of on a daily basis. Generally, this job could take up to 4 hours to complete, although this would have to be dependent on how many external walls your home has. 

What does the Job Entail?

Before carrying out the cavity insulation, a full inspection of your property needs to be carried out first. This helps assess if the type of construction of your home will be suitable for the project you have in mind. The insulation is injected via 20mm holes that are drilled horizontally around your wall, a metre apart. The insulating material then gets blown through the cavity. Then, a pressure gauge determines if there’s enough level inside. Once the right level has been reached, the drilled holes get filled. Cement is used for this purpose. Tidying up follows and a certificate will be handed to you to certify that the job has been completed. 

Related Jobs You Should Consider

Since the cavity job will not include getting the drilled and filled walls painted over, it may be best for you to hire the services of an external painter. Instead of just getting the tradesman to do a little touch-up on the area where work was done, you can have him freshen up your home exteriors instead. If there are certain parts of your home that were highlighted upon the property inspection conducted earlier on, it would be best to have this taken care of before getting the exterior painting done. 

Is Cavity Insulation Ideal for My Home?

Most of the modern properties are compatible with cavity insulation. However, a property needs to have cavity walls first before the project can be carried out. If your house has been around after the 1920s but before the 1980s, there’s a very good chance it has suitable cavity walls. If the property has been built prior to the 1920s, it will likely have a solid wall to which wall coating can be applied to your external walls in a bid to help reduce heat loss. If the property was constructed in the 1980s and onwards, you’d probably have rigid foam boards as insulation that was installed when the property was built. 

Concrete Gutters

Leaks in your concrete gutters may soak into the cavity insulation. Make sure that these gutters are properly lined to ensure that rainwater will not end up leaking into your cavity wall and into the insulation. 

Exposed Properties

If your house is located somewhere that is way too exposed might not be appropriate for this type of project. If you have walls that are exposed to diving rain will need to be duly protected with their pebbledash or roughcast so the insulation will be protected against damp issues. 

Non-Brick Walls

Homes with metal or timber frames aren’t suitable for cavity insulation injection. Masonry or brick walls are necessary for a cavity of 50mm to be injected. 

Damp Issues

If there’s even the slightest suspicion that your walls have a damp problem, a cavity wall injection is only going to exacerbate the problem. 

Masonry Condition

Tor property’s masonry or brickwork needs to be in decent shape or the insulation injection is only going to damage the fixture. Your property also needs to be in a location with no flooding risk. 

Timber or Steel-Framed Properties

Houses with timber or steel frames are never ideal for cavity wall insulation. Constructions like these require proper air circulation so rot and corrosion are prevented. These properties will usually have a damp proof course that is laid with air bricks for air circulation. Adding insulation to the cavity will only lead to condensation risks which could result in the timber or wood framing rotting. Steel frames could corrode as a result as well. 

Grants for Cavity Wall Insulation

It’s common for local companies and councils to offer promotions that will cover a percentage of the costs involved. It wouldn’t hurt to check with your local council to check local energy suppliers to see if there is such an offer. If your property hasn’t been around for 10 years, there’s a very good chance that it’s already fitted with cavity wall insulation. 

Based on the Energy Company Obligations or ECO scheme, people with tax credits or are earning an income less than but not over £16,010 and are receiving benefits are qualified for a free grant. Under the scheme, suppliers have a legal requirement to install domestic households across the country with energy-efficient technology. Besides, they will be subject to hefty fines if they will not deliver so they’ll always be happy to help any interested property owner out. 

Insulation Grants

For cavity wall and loft insulation projects, most energy companies could cover around £700. Even when you’re not sure that your project will be qualified for financial grants, it’s always worth checking nonetheless as there are suppliers that will be happy to offer free insulation to suitable homes where they are, regardless of the benefit or income status of the property owner. This is because many of them find it hard to meet their target benefit if they are to base everything on energy criteria alone. 

Cavity Wall Insulation Renewal

After you’ve established that your walls aren’t solid but cavity ones, the next step is to find out the cavity size. You’ll also need to determine if it had been filled before. You’ll need to hire the services of a accredited installer to perform a borescope inspection where a test hole is drilled on the wall and a camera will be used to assess that the cavity is at least 50mm and is empty. 

If the wall cavity is empty, then cavity wall insulation would be highly beneficial for you, provided that this part of your wall isn’t plagued with damp issues. If there’s already insulation in the cavity, renewing it is no longer necessary. Unless there’s damp, insulation doesn’t really break down. 

If there were alterations to the building that were done over time, where the job was carried out poorly, there may be a need to get the insulation topped up. Damp insulation will also need to be removed. 

Is Soundproofing Necessary for the Cavity Wall Insulation?

Insulation and soundproofing usually go together, even to the point of overlapping although they’re typically done for a variety of reasons. The application of insulation essentially contributes to the reduction of external noise. Cavity walls that aren’t filled up do lead to a noisier so it may be most sensible to get the cavity walls injected, while you also enjoy the upside of less heat loss as well. 

Health Concerns

Insulation injected into the cavity walls is generally harmless. However, there are instances with older structures where, depending on the specific type of insulation that was used or how efficiently it was installed, there may be potential health hazards. 

Modern methods and materials that are used for insulation purposes shouldn’t have any safety risks. However, if the walls were insulated years before, checking the insulation material used may be worth it. In addition, if the cavity walls were installed by untrained contractors, this may lead to problems. 

Is Planning Permission Necessary?

Based on Building Regulations, cavity wall insulation installation is considered a notifiable work. A notice is stating the insulation work that will be performed must be sent to the local council. Some buildings may be exempt to this so checking with your local authority is always advised. Most authorities will not charge anything in relation to the work that is about to be done. In some cases, if you have a reputable installer doing the work, the installers will even get the notice submitted on your behalf. Do note that the insulation materials need to be compatible with the construction materials used for the property. 

External Insulation or Cavity Wall Insulation?

External wall insulation is applied to the outside walls of your home. This is a great choice for insulation in the event that cavity walls aren’t present. If your property has solid walls or your home has timber or steel frames, the best option would be to go for external wall insulation. 

It’s important to note that insulation applied to the external walls can change the appearance of your outer walls and may not always be attractive to some people. However, it is also available in various finishing options such as timber cladding, tiles, and render coat. While all insulation types are expected to help bring your heating expenses down but you’ll start feeling the effects of cavity wall insulation quicker compared to external insulation. 

If your walls are non-traditional, EWI is the most ideal option. If you have brick or masonry cavity walls where there isn’t any damp issue, cavity wall insulation will be better as it is cheaper. The payback period is incredibly faster as well.

Additional Details

Asbestos Issues

It’s necessary for homeowners to be aware of the possible dangers of disturbing asbestos fibres and breathing them. While homes that are built around the 1990s and later no longer contain these materials, homes built before that may have them. For asbestos materials, it is advised to leave them as is and to not disturb them. The best thing to do is to leave them to the experts and to never attempt to get the removal process done by yourself. 

New Build Houses

Cavity wall insulation is a requirement for new homes, especially the ones built from the 1980s and onwards. If you’re getting a new build property from reputable builders, you can expect that the cavity wall insulation would already be installed. With new builds, you’re at least assured that the property is going to have met not only safety regulations but energy efficiency requirements as well. 

Stone Walls

Installing cavity wall insulation can get a bit tricky if you have stone walls. In this case, a more thorough examination is needed to ensure that the right material for insulation will be used. Internally, stones aren’t going to be as smooth as brick walls, so certain insulation materials might not effectively fill it up when injected into the cavity and this could lead to cold spots. 

Problems with Cavity Wall Insulation

Oftentimes, cavity wall insulation doesn’t cause any problems for the lifetime of a structure. If and when they do have problems, it would usually have to do with mould or damp. 

If you experience problems, get in touch with the professionals that did the installation. This is also why you need to be sure of the reliability and trustworthiness of the contractor you hire so you know you can trust them to resolve any future problems. This also ensures that there will be proper guarantees that will be put in place to protect you and your property in the event of future problems. Reputable providers will see to it that the problem gets assessed effectively to decide whether to fix the problem or have the insulation totally removed. 


If you used the services of shady contractors to get our installation done before and they cannot be bothered to help fix the problem, have disappeared have or have totally gone bust, you can get in touch with the Cavity Insurance Guarantee Agency or CIGA to see if there is a guarantee on the work done for you. 

Insurance Guarantee

If you’re not covered by the CIGA guarantee, take a look at the paperwork of the original job. It may be covered by insurance guarantee. Just note that when it comes to coverage, only the damages that were directly caused by the insulation will be covered. So, if there are repair works needed, this will likely not be included in the coverage. 

If you cannot get any guarantee coverage, just hire a local company to do the repairs. This time around though, see to it that they have the necessary accreditation so you can rely on them in the event that you may need future repairs. 

Removal of Cavity Wall Insulation 

In the UK, about 6 million properties are installed with cavity wall insulation. In most cases, the installation will be trouble-free. However, the country’s generally damp climate along with its high winds may cause issues on the brickwork of many homes, which can then lead to problems with the insulation. Once the insulation gets wet, drying it out whilst the cavity will be next to impossible. 

When do I need to remove it?

You’ll notice initial signs of problems in your insulation in the form of cold patches on your walls. You’ll likely experience damp patches as well, which would lead to your home becoming less comfortable. Eventually, this problem could lead to structural issues in the form of rusty wall tiles that could even lead the outer and inner walls separating. 

Just like any damp problem, damp in your cavity wall insulation must never be ignored or it will likely end up getting worse, which could lead to even more serious and costly repairs later on. If you believe that there may be damp problems in your home, call the installer and have them check the issue. If they aren’t around, contact an insulation expert as soon as you can to get the problem addressed fast.