Cavity Wall Insulation In Scotland

In Scotland, keeping our homes warm and energy-efficient is essential. This guide delves into the world of  cavity wall insulation, a method many Scots are turning to. Whether your home was built after the 1920s or you’re curious about walls with a gap, we’ll explore how insulation can transform your home’s warmth and slash those heating bills. Dive in to discover more about this energy-saving solution.


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What Is Cavity Wall Insulation?

Cavity wall insulation is a game-changer for many homes in Scotland. But what exactly is it? Let’s break it down.

Homes are usually made with walls that protect us from the outside elements. Some of these walls, known as cavity walls, have two layers with a small gap or cavity in between. This gap can let out a lot of the warmth from our homes, especially during those chilly Scottish winters. That’s where cavity wall insulation comes into play.

To get cavity wall insulation installed, professionals fill this gap with insulating materials. These materials act as a barrier, preventing the heat inside our homes from escaping too quickly. Think of it as wrapping your home in a cosy blanket, keeping the warmth in and the cold out.

The result? A home that stays warmer for longer, helping us save on heating bills and making our living spaces much more comfortable.

But it’s not just about comfort. By having cavity wall insulation, we’re also taking a step towards better energy efficiency. This means our homes require less energy to stay warm, which is not only good for our pockets but also for the environment. In a world where we’re all trying to do our bit to reduce our carbon footprint, improving our home’s energy efficiency is a smart move.

In short, cavity wall insulation is a simple yet effective way to keep our homes warm, reduce energy bills, and contribute to a greener future.

How Does Cavity Wall Insulation Work?

Understanding how cavity wall insulation works is simpler than it sounds. Here’s a look at the basics:

Many homes in Scotland are usually made with walls that have two layers. If you think of a sandwich, these layers are like slices of bread, and the gap in between is the filling. When these walls are made of brick, the gap or cavity between them can let out a lot of the warmth from inside our homes. This is where cavity wall insulation steps in to save the day.

To insulate this cavity, professionals use a special insulation material. This material is designed to trap heat, acting like a thermal barrier. Imagine filling the gap in our sandwich with a layer of warm, fluffy filling. This filling stops the heat from escaping from inside the sandwich, keeping it warm and toasty.

Now, you might wonder, what if my home has a solid wall without a gap? Solid wall insulation is a bit different. Instead of filling a gap, insulation is added to the inside or outside of the solid wall. This works in a similar way, trapping heat and boosting the wall’s insulating properties.

Whether it’s a cavity wall or a solid wall, the goal is the same: to use insulation material where possible to keep the warmth inside our homes. By doing this, we ensure our homes stay cosy, our energy bills stay low, and we do our bit for the environment.

eco home insulation

How Much Does Cavity Wall Insultation Cost?

Initial costs

Getting cavity wall insulation for your home is an investment. The cost can vary depending on the size of your home and the specific type of insulation material chosen. Typically, insulating cavity walls of an average-sized home might range from a few hundred to over a thousand pounds.

Installation process

The process involves injecting insulation material into the gap of cavity walls. This is done by drilling small holes in the external wall and then filling the cavity with the chosen insulation. The holes are then sealed, leaving the wall looking as it did before. This sort of work usually starts from around £300 but could be more or less, depending on the size of the job.

Long-term savings

While there’s an upfront cost, the savings in the long run can be substantial. With well-insulated cavity walls, you’ll spend less on heating bills. Over time, the insulation can pay for itself with the amount you save on energy. Properly insulating your home can prevent around 33% of heat from escaping. This means you could save around £455 a year on your energy bills.


It’s worth noting that many installations come with a guarantee. Also, the Cavity Insulation Guarantee Agency offers an independent 25-year guarantee on insulation work. This gives homeowners peace of mind, knowing that their investment is protected. This is good seeing as that cavity wall insultation extraction can cost around £1,700.

While there’s a cost to cavity wall insulation, the benefits in comfort and savings make it a wise choice for many Scottish homeowners.

cavity wall insulation

How Much Can Cavity Wall Insultation Save?

Cavity wall insulation isn’t just about keeping your home cosy; it’s also about the pennies and pounds you could save. Let’s break down the savings.

Firstly, by adding cavity insulation, you’re boosting your home’s energy efficiency. This means your heating system doesn’t have to work as hard to keep your home warm. Over a year, this can significantly save you money on your energy bills.

Reports suggest that an average-sized home in Scotland could save anywhere from £90 to £455 a year after installing cavity wall insulation. That’s a tidy sum that could be spent on other home improvements or a nice treat for the family.

In the long run, these savings add up. So, the amount you could save in the following years makes it a smart investment for both your pocket and the planet.

Types of Cavity Wall Insulation

Mineral wool

One of the most common types of insulation material is mineral wool. Made from natural minerals, this fibrous material is packed into the cavity between external walls. It’s a popular choice because of its excellent heat retention properties. If your home has an inner layer of brick or concrete block, mineral wool can be a snug fit.

Polystyrene beads

For homes with narrower cavities or those made of brick or stone, polystyrene beads are often used. These tiny beads are blown into the cavity, filling up the space and acting as a barrier against heat loss. They’re lightweight, making them suitable for cavity wall installations where other materials might be too heavy.

Polyurethane foam

This insulating material is a bit different from the others. Instead of being packed or blown in, it’s sprayed into the cavity where it expands and sets. This foam is especially good for homes with irregular cavities or solid walls that need an extra layer of insulation. It forms a continuous layer, ensuring no gaps are left unfilled.

Choosing the right type

The best insulation for your home depends on a few factors. The type of external walls you have, whether they’re solid walls or cavity walls, can influence your choice. Also, the age of your home and the materials it’s made from play a role. For instance, older homes with walls made of brick or stone might need a different approach than newer homes with a clear inner layer.

While there are various types of insulating materials available, their purpose remains the same: to boost your home’s energy efficiency. By understanding the different types and their benefits, you can make an informed decision that’s perfect for your home.

Issues With Cavity Wall Grants

  • Eligibility criteria: Not everyone can access these grants. They’re often targeted towards low-income households or those receiving specific benefits. This means some homeowners might miss out even if they need the insulation.
  • Application process: While the process to apply for a cavity wall insulation grant is straightforward, it requires homeowners to provide detailed information about themselves and their homes. This can be time-consuming and might deter some from applying.
  • Professional work only: The insulation work covered by these grants must be done by experienced and vetted professionals selected by the government. While this ensures quality, it means homeowners cannot choose their preferred installer or do the work themselves.
  • Limited funds: While the grants aim to support as many homeowners as possible, there’s always a cap on available funds. This means some eligible homeowners might have to wait or might not receive the grant at all.

Although cavity wall insulation grants offer a fantastic opportunity to improve home energy efficiency, it’s important to be aware of potential challenges. Being informed can help homeowners navigate the process more smoothly

Do I Need Cavity Wall Insulation?

Deciding if you need cavity wall insulation can be straightforward. First, consider your home’s age. If your home was built in the last 20 or 30 years, it might already have cavity wall insulation installed. This is the case for most homes built after the 1920s. But for older homes, there’s a chance they might benefit from it.

Look at your external walls, more specifically, solid walls, ones usually made of brick or concrete blocks. If they are walls with a gap or cavity walls, they’re likely suitable for cavity wall insulation. Remember, around a third of the heat in an uninsulated home escapes through walls. By insulating them, you can keep more of that warmth inside.

Not only does this make your home cosier, but it can also help improve energy efficiency. This means lower energy bills and a reduced carbon footprint.

Are There Grants for Cavity Wall Insulation?

Yes, there are grants available for those considering cavity wall insulation. The current scheme, known as ECO4, is a government-backed initiative aimed at enhancing the energy efficiency of homes. It’s regulated by Ofgem and is set to run until 2026. Here’s what you need to know:

Free cavity wall insulation

If you’re on a qualifying benefit, you can access grants that cover the entire cost of professional installation. The home should be privately owned or rented and occupied during the survey.

Qualification criteria

  • Must receive a specific qualifying benefit.
  • The property should have an EPC rating of D, E, F, or G.
  • The grants are funded by major energy suppliers and do not need to be repaid.


Yes, through the government’s ECO4 scheme, eligible homeowners in Scotland can access free cavity wall insulation. The scheme aims to enhance energy efficiency in homes and is set to run until 2026.

Cavity walls were designed to prevent dampness. When cavity wall insulation is correctly installed, it doesn’t cause dampness. However, if moisture penetrates the external wall and reaches the insulation, it can transfer to the interior.

For walls in the UK, the recommended thickness for polyisocyanurate insulation is typically around 125 mm to achieve the desired U-value of 0.17 W/m2K. But, the thickness can vary based on specific requirements and building design.

The efficiency varies based on the material used and your home’s needs. Mineral wool, polystyrene beads, and polyurethane foam are popular choices, each with unique benefits. The best option depends on the home’s specific requirements. Luckily, an installer will be able to tell.


It’s clear that a lot of heat escaping – about a third of the heat to be exact – from our homes is likely due to unfilled cavity walls. By investing in cavity wall insulation, not only can we significantly reduce our energy bills, but we also take a positive step towards shrinking our carbon footprint.

For Scots keen on a warmer home and a greener planet, it’s a win-win solution. Let’s make our homes more energy-efficient and eco-friendly.