ECO Energy Service's

Is Cavity Wall Insulation Worth It?


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When you think about improving your home, you might ask if cavity wall insulation is worth it. Without a doubt, this method boosts your home’s warmth by filling the wall gap with insulating material. Moreover, it’s a smart move that can cut down your energy bills and help the environment.

Insulating your walls stops heat from slipping away, which means you use less energy. This could save you as much as £160 every year, and the best part? It might pay for itself in under five years. Plus, your home will feel just right, warm in winter and cool in summer.

But there are some downsides. If it’s not put in correctly, you could end up with damp walls, and that can lead to mould. Also, they have to drill holes to install it, and if they don’t seal them upright, it can make your house look not so nice.

Now for homes built after the 1920s, cavity wall insulation is usually a smart choice. It’s an affordable way to make your home more energy-efficient and comfortable. Just remember, it’s important to have a certified expert do the installation to dodge any problems. So in simpler terms, if you’re aiming to make your home energy-smart, starting with cavity wall insulation is a wise move.

What's the Impact on the Environment?

Cavity wall insulation has a positive impact on the environment. So by improving your home’s energy efficiency, you can reduce the need for heating and cooling. Moreover, you can use less energy. As a result, you will be able to cut down on carbon emissions from power plants that burn fossil fuels. In fact, by insulating your walls, you could lower your carbon footprint by about 1100kg of CO2 each year. So, not only does it make your home more comfortable, but it also helps in the fight against climate change.

How does it compare to other Insulation methods?

Cavity wall insulation is just one of many ways to keep your home warm. Compared to other methods, it’s unique because it fills the space between your home’s walls. Here’s how it stacks up:

  • Spray Foam: This expands to fill the cavity and creates an airtight seal. It’s super effective but can be more expensive.
  • Mineral Wool: This is great for older homes. It’s made from natural or synthetic fibers and is quite common.
  • Beads and Granules: These are tiny foam particles that fit into small spaces well. They’re good for walls that aren’t too thick.
  • Rigid Insulation Boards: These are stiff panels that can be cut to fit. They work well for new homes with bigger wall cavities.
  • Cavity Batts: These are like blankets for your walls and are covered with water-resistant film. They’re easy to install.

Each type has its pros and cons. But overall, cavity wall insulation is a solid choice for many homes, especially if you’re looking for a balance of cost and effectiveness.

What's the process of getting cavity wall insulation?

Getting cavity wall insulation is a straightforward process that can make your home more energy-efficient. Here’s what typically happens:

  • Assessment: First, a professional checks if your home has cavity walls and if they’re suitable for insulation.
  • Drilling: Next, they drill small holes in the outer wall at regular intervals.
  • Insulation Injection: Through these holes, they blow in insulating material, like mineral wool or foam beads.
  • Sealing: Finally, they seal the holes to match your wall, leaving no trace of the work.

It’s a quick job, usually done in a few hours, and it doesn’t mess up your home. Just make sure you get a certified installer to do it right and avoid any damp or heat loss issues. This way, you’ll enjoy a warmer home and lower bills!

Are there any alternatives to cavity wall insulation?

Certainly! There are several alternatives to traditional cavity wall insulation that can be considered, especially if your property is not suitable for it or if you’re looking for more eco-friendly options. Here are some alternatives:

  • Internal Wall Insulation: Without a doubt, this involves fitting rigid insulation boards to the wall. But you can also add a building stud wall filled in with insulation material. But you need to finish it with plasterboard.
  • External Wall Insulation: This method adds a weatherproof insulating layer to the outside of the wall. It is then covered with render or cladding.
  • Natural Materials: Options like hemp wool, sheep wool, thermal cork shield, and denim insulation are eco-friendly. Moreover, they offer good thermal performance.
  • Innovative Materials: Aircrete granulation and multiport are modern alternatives that provide effective insulation.
  • Polystyrene Beads/Granules: These can be injected into the cavity in a similar way to traditional insulation materials.

How can I check if my property already has cavity wall insulation?

To check if your property already has cavity wall insulation, you can use several methods:

  • Visual Inspection: First, look for small, filled holes on the external walls. These are typically a sign that insulation material has been injected into the cavity.
  • Borescope Inspection: Next, a professional can drill a small hole in your wall. Moreover, they insert a borescope to visually inspect the cavity for insulation.
  • Thermal Imaging: Now, this non-invasive method uses a thermal imaging camera to detect temperature differences in the walls. As a result, it indicates the presence or absence of insulation.
  • Check Property Age: But, if your property was built after the 1990s, it’s likely that it was constructed with cavity wall insulation.
  • Property Paperwork: Review any available construction documents for information about insulation.

It’s recommended to consult with a professional to conduct these checks, especially for borescope and thermal imaging inspections.

How long does cavity wall insulation last?

Cavity wall insulation is designed to be a long-lasting solution for improving a home’s energy efficiency. Generally, it’s expected to last for about 25 years. But it can vary depending on several factors. If installed correctly, some types of cavity wall insulation can last as long as the building itself. However, factors such as poor installation or the use of inferior materials can reduce its lifespan. For instance, expanded foam insulation may shrink over time and could become less effective after several years. But, on the other hand, blown-in types of cavity wall insulation, unless damaged, should last for up to a century.

So, if you’re considering cavity wall insulation for your home, it’s essential to ensure that it’s installed by a reputable professional to maximize its effectiveness and longevity.

How can I maintain my existing cavity wall insulation?

maintain existing cavity wall insulation

Here are some tips to help you keep your insulation in top condition:

  • Annual Inspections: First, conduct routine inspections of your cavity walls to identify any signs of damage or moisture infiltration. Check the brickwork annually. Also, ensure the small holes filled post-installation remain sealed.
  • Cavity Barrier Checks: Second, ensure that cavity barriers stay intact and functional.
  • Monitor Energy Efficiency: Next, keep an eye on your energy bills over the months. As a result, you can evaluate the performance of your insulation.
  • Look for Dampness: Moreover, be vigilant for any signs of dampness or water ingress. These can compromise the insulation’s effectiveness. They may also lead to mold growth.
  • Professional Assessment: If you suspect any problems or it’s been a while since the insulation was installed, consider getting a professional assessment. This way you can check the condition of the insulation and address any issues.

Is it worth topping up cavity wall insulation?

Topping up your cavity wall insulation can be beneficial, especially if the existing insulation has settled or degraded over time. Often this can happen with certain materials like expanded foam or polystyrene beads. Here are some points to consider:

  • Energy Efficiency: Firstly, if your energy bills have been rising, it might indicate that your insulation is no longer performing optimally. So topping up could help improve the thermal efficiency of your home.
  • Material Condition: Secondly, some materials, like mineral wool, rarely have issues. However, others may move or degrade within the cavity. So if you’ve lost a significant amount of insulating material, it is worth topping up cavity wall insulation. Moreover, it could restore its effectiveness.
  • Installation Quality: Finally, if the original installation was rushed or done improperly, topping up could correct these issues. It can also extend the life of your insulation.

What are the costs associated with topping up cavity wall insulation?

The costs associated with topping up cavity wall insulation can vary depending on several factors. For instance, the size of your property, the type of insulation material used, and the labour costs in your area. Here’s a general idea of what you might expect:

Cost Description

Cost Range

Per Square Foot

£0.78 – £1.56

Mid-floor Flat (Starting from)


Detached Property (Up to)


Material Costs

£31.25 – £58.59

Installation Costs

£97.66 – £207.03

These are approximate figures and actual costs may vary. It’s always a good idea to get multiple quotes from professionals to ensure you get the best deal.

What is the cost of cavity wall insulation?

The cost of cavity wall insulation in the UK can vary depending on a few factors, but here’s a breakdown to give you an idea:

Factors affecting cost include property size, property type, material used and of course your location.  

Cost by property type:

Property Type

Cost Range

Detached House

£2,500 – £4,600

Semi-detached House

£450 – £2,700

Terraced House

£340 – £1,500

Flat (mid-floor)

£410 – £1,000

Material Costs per square meter:


Cost Range

Mineral Wool (glass or rock)

£13 – £18

Expanded Polystyrene (EPS) beads

£18 – £22

Polyurethane Foam

£22 – £26

These are just averages, and you can get quotes from local installers for a more accurate estimate.

Bottom line

So, is cavity wall insulation worth it? It depends on your specific situation. If you’re looking for ways to make your home more comfortable, save on energy bills, and potentially reduce your environmental impact, then cavity wall insulation could be a great option. However, remember to factor in the upfront cost and ensure your home is suitable for the installation. Consulting a qualified professional can help you determine if cavity wall insulation is the right choice for your home.


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