How to Remove Cavity Wall Insulation and What Are the Costs?

How to remove cavity wall insulation

Cavity wall insulation has a lifespan that usually lasts several decades, making it an enduring feature of a building’s thermal efficiency. However, this longevity can sometimes lead to a situation where it’s out of sight, out of mind. Because it’s hidden within the walls, maintenance is often overlooked or underestimated. 

Old or failing cavity wall insulation can lead to several consequences, including decreased performance, health issues due to mould and pest infestations, and expensive repairs. To avoid these issues, homeowners should proactively address their insulation maintenance needs. But how do you set about removing cavity wall insulation and what are the costs involved? 

How Is Cavity Wall Insulation Removed? 

There are various methods to remove insulation from cavity walls, but by far the most common is by inserting high-pressure air into a strategically placed access point in an external wall to dislodge and break up old insulation material. 

The dislodged cavity wall insulation material is then collected in a containment unit, ensuring safe disposal and preventing harmful particles from being dispersed into the environment.

Here’s a brief step-by-step guide to cavity wall insulation removal that the majority of insulation companies will follow:

Step 1: Survey the Property 

Upon arrival, a member of the team surveys your property and assesses the type of insulation installed. 

There are three common types of cavity wall insulation: blown-in insulation (sometimes called cellulose insulation), polystyrene insulation, and urea formaldehyde foam insulation. 

Blown-in fibre insulation is the easiest to remove because it’s made from loose-filled fibreglass or mineral wool. Polystyrene insulation, on the other hand, tends to interlock and settle over time, so it takes more effort to extract. 

Urea-formaldehyde foam (UFFI) was common in the 70s and 80s, but not so much today because of the health risks it poses. UK Building Regulations ban the use of this foam in most buildings, except in areas with an inner leaf constructed of blocks or bricks. 

UFFI removal requires specialised equipment, such as cutting tools and extraction systems, to minimise exposure to airborne particles and formaldehyde gas. 

Step 2: Drill the Wall

Once your insulation expert has established the type of insulation they’re dealing with, the removal team prepares the area by setting up protective barriers to minimise dust and debris. 

The cavity wall extraction team will then create an access point on the external walls (if there isn’t already) and insert a specialised industrial vacuum inside the cavity. 

Step 3: Suction and Removal 

Upon turning on the machine, the industrial vacuum collects the loose insulation material from inside the cavity wall. 

The loose material will travel to the collection point, where it’s bagged and later removed. 

If your insulation specialists encounter obstructions in the cavity, such as piping or wiring, they will carefully navigate around them to ensure safe and thorough removal. 

In rare cases, the installer might temporarily have to move or adjust this obstruction. It entirely depends on how these obstructions are positioned and installed.

Step 4: High-Pressure Air Gun 

After removing loose insulation material, a high-pressure air gun will usually be inserted into the wall. 

The compressed air from the air gun will hit the old insulation to loosen the debris and move it towards the suction point. This method will be used all over the home until the cavity is free of the old insulation.

During the removal process, thermal cameras and endoscopes are usually used to not only assess the condition of the cavity but to also ensure proper extraction.  

Step 5: Seal the Holes 

After the extraction, any holes that were made in the inner and outer walls of the home will be sealed with cement and painted over to match your home’s exterior finish. Your installer should then clean the work area and remove any remaining debris or particles. 

Before extraction is complete, a final inspection ought to be carried out to ensure that the cavity is clean and ready for any necessary repairs or re-insulation. 

Can I Remove the Cavity Wall Insulation Myself? 

Unfortunately, no; the removal of cavity wall insulation is really a task that only professionals like those recommended by Insulation Advisor can properly—and safely—handle. 

Even with proper knowledge and tools, cavity wall insulation removal is a complex and potentially risky task. If done incorrectly, it might lead to structural damage, either to internal walls or external walls, as well as added safety hazards. 

The installer you find through us will be trained to work safely around unexpected obstructions like electrical wiring and plumbing that can get damaged during the removal process. 

When undertaking cavity wall extraction, professional teams will use tools and equipment designed specifically for the job. These tools ensure a thorough and efficient removal of failing cavity wall insulation, while minimising the risk of damage to the walls and other components. 

How Long Does Cavity Wall Insulation Removal Take? 

Cavity wall insulation removal is a relatively slow process, compared to other types such as blanket loft insulation removal, because it takes extra care to do properly and thoroughly. 

It usually takes between one to three days to complete, depending on the type of insulation that your insulation removal specialists are dealing with, the size of the building, and any unexpected challenges that might arise. Straightforward removal usually takes a day or two, but specialised jobs may take longer. 

Larger buildings will naturally take longer to complete. The same is said if there are hidden obstacles within the cavity, difficult-to-reach areas, or structural issues that need addressing. Additionally, you will usually want to install cavity wall insulation in place of the old material you have removed.

How Much Does Cavity Wall Insulation Extraction Cost? 

There’s no single answer to this question, as the cost of removal depends on multiple factors. These factors include the size of the building, the type of insulation to be removed, and the complexity of the project. 

Most companies charge between £25 to £45 per square metre of wall, based on where you live in the UK. For example, the rate in Cambridge would be likely to be much greater than the rate in South Wales.

The price of cavity wall insulation removal will also increase if the job requires scaffolding. 

For most properties, ladders are more than enough to finish the job. But if your installer can’t access a section of the wall using a ladder, they may have to erect a scaffolding structure. This will cost an additional £300 to £600. 

Here’s how much to expect on a standard job: 

  • Inspection: £200 to £300
  • Front wall only: £1500
  • Front and rear walls only: £1750 to £2250
  • Small semi-detached home with three walls: £1750 to £2250
  • Large semi-detached home with three walls: £2500 to £3000
  • Small semi-detached home with four walls: £3000+ 
  • Large semi-detached home with four or more walls: £4500+

Why Remove Cavity Wall Insulation?

With all the costs associated with the removal of cavity insulation, you’re probably wondering if it’s even worth undertaking such a project. In most cases, the answer is yes. 

There are several reasons why you should remove a cavity wall insulation: 

Poorly Installed Installation 

Cavity wall insulation is an excellent way to reduce your energy bills. Insulation grants exist for this reason: to encourage and support homeowners in improving the energy efficiency in their homes. 

But in cases where incorrectly installed insulation is in place, this can lead to a range of issues that not only negate the potential benefits but also create new problems, including: 

  • Moisture issues
  • Damp walls
  • Reduced energy efficiency 
  • Increased heating bills
  • Cold spots 
  • Fire hazards
  • Structural damage

To prevent these issues, the only solution is to remove the existing insulation and then have new cavity wall insulation installed. 

Poor Performance 

As with any structural installation, cavity wall insulation degrades over time due to natural wear and tear, moisture and mould, and pest infestations. These issues compromise the insulation’s integrity, leading to decreased thermal performance and energy waste. 

Moisture Issues 

Cavity wall insulation isn’t immune to moisture issues. As years turn into decades, the potential for moisture-related problems increases, especially if you property is overly exposed to wind driven rain. 

Rain penetration and moisture infiltration greatly impacts the performance of insulation and the overall health of the building. It creates damp issues and conditions conducive to mould growth, which not only affects the integrity of the walls but can also impacts indoor air quality. Prolonged exposure to moisture can also cause rot and decay within the walls, which can result in much more expensive repairs further down the line. 

Unsuitable Insulation Material 

In 1984, the UK government implemented a building regulation that mandated the installation of insulation in new buildings. Small companies took advantage of this regulation and approached older homes, offering insulation to enhance energy efficiency and reduce heating costs. Materials were easily accessible, so the government encouraged these companies.

Unfortunately, this approach resulted in several problems. For one, the insulation material that was used was often made of urea-formaldehyde foam. Urea-formaldehyde, when broken down, releases carcinogenic fumes into the home. 

Moreover, the homes built before the 1980s had narrow cavities, which weren’t suitable for insulation installation. Because of this, homeowners with old cavity wall insulation should consider removal and replacement to address health concerns and upgrade their insulation to modern materials. 

Failing Insulation 

Insulation has a lifespan of 20 to 80 years, depending on the composition and materials used. If you’re living in an older home and encounter problems such as: 

  • Unusually high energy bills 
  • Draughty house
  • Mouldy scent
  • Pest infestation

Then it might be time for a cavity wall insulation extraction and replacement. 

Addressing these signs with a professional removal and replacement can significantly improve your home’s energy performance and overall comfort. 

Maintain Property Value

Failing wall insulation can drastically reduce the value of your home. 

Insufficient insulation can lead to temperature fluctuations, drafts, and uncomfortable indoor conditions, which aren’t appealing to buyers searching for a cosy living environment. 

A well-insulated home is seen as a more valuable investment due to its energy efficiency and reduced maintenance needs. 

By removing a failing wall insulation (and replacing it with a new one), you’re preserving the integrity and value of your home. 

Can You Repair a Cavity Wall Insulation Instead of Removing It? 

In some situations, yes; your installer may be able to repair rather than replace a cavity wall insulation. It really depends on several factors, including: 

  • Type of insulation material used: Some materials are more amenable to repairs, while others aren’t.
  • Extent of the damage: If the damage is localised and not too extensive, it could be repaired without needing to remove all of the insulation. 
  • Compatibility: Repairs need to be compatible with the existing insulation material. If the home is made with urea-formaldehyde insulation, for example, it won’t be repairable because this type of material is no longer used.  
  • Access: If the damage is in an easily accessible location, repairs might be possible. 
  • Long-term effectiveness: Repairs should provide a lasting solution to a problem. If they don’t address the underlying issue, their effectiveness might be short-lived. In such cases, it’s better to remove the damaged insulation and replace it with better insulation. 

How To Remove Cavity Wall Insulation & The Costs Conclusion 

We hope this post on how to have cavity wall insulation removed gives you a general idea of how the process works. To summarise, your installer will insert an extraction system into strategically drilled positions on the cavity walls to suck out the failing insulation. 

They’ll then use a high-pressure air gun to loosen any remaining old cavity insulation material. 

When the cavity is emptied, it should be refilled with a suitable option, such as injecting special insulation material like polyurethane foam, or some other alternative. Cavity wall extraction teams will cover up the holes, usually in the outer wall, with cement, so you would barely know that they have been there.

To find the right company for your cavity wall insulation removal needs, rely on Insulation Advisor – we’ll compare trusted, local installers, so you don’t have to do any of the hard work yourself!

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