Cavity Wall Insulation Cost

How Much Does Cavity Wall Insulation Cost?

How much does cavity wall insulation cost without scaffolding?

Without the use of scaffolding, the average cost of insulating cavity walls in a mid-floor flat would land around £250 to £330.

So how much should you set aside for your budget?

You’d need to set aside a budget of about £400 to £495 to have the same work undertaken in a semi-detached house, £650 to £850 in a detached property, or £275 to £320 with a terraced house. If scaffolding is used, it would add approximately £100 to the above costs.

What can affect the overall costs?

There are a range of cost factors that can shape how much you’d need to spend to have cavity walls insulated.

Among them are the number of tradespeople hired, ease of access, the type of insulation used, size/type of property, the state of the work area, and the location of the homeowner’s property.

As for the final point, the reason that where you live is relevant is due to the fact that labour costs vary throughout the nation.

This is because contractors have different living costs to meet in different regions of the country.

Labour rates tend to be higher in the southeast (especially London) but below the UK average in the north of England, Northern Ireland, and Scotland.

Cavity Wall Insulation Prices

The table below shows the average costs of wall insulation:

What are the Supply Costs of Insulating a Cavity Wall?

In this section, we’ll delve into the material costs involved in insulating cavity walls in a property. This excludes the labour cavity insulation wall prices.

The average supply costs of insulating cavity walls without the use of scaffolding is £200 to £300 for a mid-floor flat, £300 to £400 for a semi-detached house, £500 to £600 for a detached house, and £175 to £225 for a terraced house or bungalow.

Supply Cost of Installing Cavity Wall Insulation

What are the Additional Costs of Cavity Wall Insulation?

The added expenses of cavity wall insulation include the number of tradespeople hired and charges for excess mileage, if applicable. Let’s take a closer look at some potential additional costs.

Minimum Fee

To start with, you may face a minimum charge on your bill when having cavity walls insulated. This may be a set amount.

For example, if you were paying per day of labour, then whether the job takes four hours or eight hours, you’d pay for a day of labour regardless. Hence, you face a minimum one day’s labour in costs for every new work day started.

Size/Type of Property

The larger the property, the more you can expect cavity wall insulation to cost. The type of property is also relevant, not just because of its link to scale, but also given that some properties can have different structures and forms, which could make this type of work easier or more difficult.

Wall Preparation

When getting cavity wall insulation installed, there may be a number of jobs needed to prepare the wall. Good preparation will ensure the installation is effective and doesn’t cause problems down the line.

This could include:

• Repairing Damaged Bricks or Repointing - Fixing cracks or structural issues
• Resolving Damp Issues - Cavity insulation can make them worse
• Installing Air Vents - To maintain airflow and prevent condensation
• Cleaning The Cavity - Clearing debris such as old insulation or rubble

Type of Insulation

Another relevant factor is the type of insulation used. The three most prominent forms of wall cavity insulation used in the UK are

• Polystyrene Beads / Granules
• Blown Mineral Fibre
• Urea Formaldehyde Foam

Each type comes with its own price point.

Number of Tradespeople

Another relevant factor is the number of tradespeople hired. The more cavity wall insulation installers employed, the higher the labour cost will be and vice versa.

Of course, whether this would be an added expense overall will depend on factors such as how well the labourers work together, given that the more workers on the project, the quicker it will take.

Duration

Of course, the longer the insulation work lasts, the more the labour costs will likely be. This may not apply, for example, if the labour costs are charged as a set amount.

Tradesmen Costs for Cavity Wall Insulation

In this section, we’ll delve into the labour costs involved in insulating cavity walls. This means excluding the supply costs. We’ll also look at the factors that can shape and influence the labour costs for cavity wall insulation.

The average labour cost for this type of project is around £50 to £65 per hour. However, in most cases, labour fees will be based on the size/type of the property, with a set price given in advance.

Expect to pay on average:

• £50 to £130 - for a mid-floor flat
• £100 to £195 - for a terraced or semi-detached house
• £200 to £300 - for a detached property

How Long Does It Take to Insulate a Cavity Wall?

Let’s now discuss the timeframes involved in insulating a cavity wall based on size/type of property and whether or not scaffolding was used (so the same measures we used for discussing the costs).

We’ll also consider the factors that shape the duration of insulating a cavity wall in this section.

To insulate a cavity wall in a mid-floor flat would take about one to two hours. Where no scaffolding is used, it takes about an hour or two to perform this work on a terraced house, two to three hours for a semi-detached house, or three to four hours in the case of a detached property.

When scaffolding is used, you should add an additional hour to the time frames given above.

As for the factors in determining how long the job will take, these are, among others:

• Ease of access
• The state of the work area
• The number of tradespeople hired
• Weather conditions (if working from outside)

Types of Cavity Wall Insulation

As discussed earlier, cavity wall insulation is essential for improving a home's energy efficiency and reducing heating costs. There are three main types of cavity wall insulation available. Let’s take a closer look at these options to help you determine which might be the best fit for your property.

Blown Mineral Fibre Insulation Cost

Blown mineral fibre insulation is one of the most widely used methods for cavity wall insulation. It consists of fine strands of mineral wool or fibreglass, which are blown into the wall cavity using compressed air.

This type of insulation is certified by the British Board of Agrément (BBA), which ensures that it meets industry standards for safety, quality, and performance. It is also recognised for its durability and effectiveness when professionally installed.

The cost of this type of cavity wall insulation is around £15 to £20 per square metre.

Pros:

• Highly effective at reducing heat loss
• Fire-resistant properties
• Approved and certified by BBA, ensuring quality assurance

Cons:

• Not always the suitable for properties with narrow cavities

Polystyrene Beads Insulation Cost

Polystyrene bead insulation is an advanced method of cavity wall insulation. These small, lightweight beads can be injected into the cavity either loose or coated with a light, sticky resin. The resin helps bind the beads together, reducing the risk of settlement over time, although the beads naturally interlock and hold their position once inside the cavity.

Like other types of cavity wall insulation, compressed air is used to blow the polystyrene beads into the wall space. This allows the beads to fill the cavity evenly. Once more, these materials are covered by BBA certificates.

Polystyrene beads for cavity wall insulation tend to range from £20 to £25 per square metre.

Pros:

• Widely used and proven method
• Advanced technology ensures a consistent and effective fill
• Less risk of gaps or cold spots compared to some other materials

Cons:

• Can be tricky and potentially messy to install
• Higher cost compared to basic insulation types

Urea Formaldehyde Foam Insulation Cost

Urea formaldehyde foam is a type of cavity wall insulation created on-site by mixing two chemical components. These chemicals are injected simultaneously into the wall cavity, where they react to form a foam that expands and hardens, filling all available space.

This makes it particularly suitable for narrow or irregular-shaped cavities that are difficult to insulate using traditional materials.

This method is governed by strict standards. The material used complies with BS:5618, while the injection process itself is covered by BS:5617, ensuring that the installation meets necessary safety and performance requirements.

The cost of this type of insulation is normally around £25 to £45 per square metre.

Pros:

• Highly effective at insulating narrow or hard-to-reach cavities
• Useful for older buildings with non-standard wall structures

Cons:

• More complex installation process
• Can be harmful and may require more safety measures

Benefits of Cavity Wall Insulation

There are many advantages to insulating cavity walls. Let’s break down some of the prominent benefits of this type of work.

Cost-Effective Way of Saving On Energy Bills

Though insulating cavity walls will generally cost several hundred pounds, it is one of the cheapest ways of insulating your home and saving money on heating bills in the long-run.

It is usually a lot cheaper than, for instance, having all the windows in a property replaced with double-glazed windows.

On average, cavity wall insulation would save you about £100 to £200 per year. As a result, you’d be saving more than you spent after just two years.

Keeps a Home Warmer

With good heat-retaining qualities, cavity wall insulation can keep a property warmer by reducing heat loss. This can be especially helpful during the cold winter months and may help deal with cold spots in your home.

More Eco-Friendly

Not only does cutting down on heating bills save money, but it’s of course also better for the environment as it will bring down the carbon footprint of your home. It helps to make a home greener and more suited to the 21st century.

How Much Does It Cost to Remove a Cavity Wall Insulation?

In the rare event that the insulation fails completely or is letting dampness into a property, it may prove sensible to have cavity wall insulation removed.

In other cases, if urea formaldehyde foam has been used, it may be the case that the chemicals being released are acting as a health hazard.

Regardless of the reason, it’s likely to cost about £18 to £24 per square metre to remove cavity wall insulation.

Please note that if cavity wall insulation has resulted in damage to your walls, you can look into the option of making cavity wall claims for compensation.

This could prove helpful if there are any cavity wall insulation problems.

FAQs

Q: How long does cavity wall insulation last?

A: Cavity wall insulation typically lasts 25–30 years if installed correctly and kept dry. Most installations come with a 25-year guarantee.

Q: How do I know if I have cavity wall insulation?

A: It will depend on the wall type. A brick wall over 260mm thick may contain a cavity, but this is not guaranteed.

You should expect a narrower wall to be solid. The same is true of stone walls. If in doubt, you can always hire a professional to come by and take a look.

Q: Are there any cavity wall insulation grants?

A: Yes. For more information visit the GOV.UK page about energy grants.

Q: What can happen if a cavity wall is installed incorrectly?

A: It may lead to an internal accumulation of moisture and cold spots.

Q: How thick is a cavity wall in general?

A: On average, a regular cavity wall will be about 250mm in thickness as opposed to 220mm of a solid brick wall.

Author: Dean M

I have a Bachelor's Degree in Creative Digital Media, I'm a freelance writer and I've worked for clients such as the British Blockchain Association and I have experience in writing articles, YouTube video scripts, online guides and newsletters. I have written and produced many short films as well as a web series and feature film. I am also currently working on a novel.