What Is Solid Wall Insulation

Solid wall insulation cladding

A Comprehensive Guide to Solid Wall Insulation: Costs, Savings, Benefits

Are you tired of skyrocketing energy bills and an uncomfortable home?

Discover the benefits of solid wall insulation by understanding “what is solid wall insulation” to not only reduce your heating costs but also make your home more energy efficient and eco-friendly.

Let us guide you through the process of exploring insulation options, and making informed decisions for a warmer and greener future.

Short Summary

  • Understanding solid walls is essential for selecting the best insulation method.
  • Insulating solid walls helps minimise heat loss and improve energy efficiency in a home.
  • Various government financial assistance programs are available to help offset costs associated with insulation projects, while other green initiatives such as renewable energy sources can create an environmentally friendly living space.

What Are Solid Walls

A house with solid walls and insulation materials

Solid walls are a common construction type in the UK, comprising approximately 45% of homes.

Unlike cavity walls, solid walls do not contain gaps or cavities, resulting in a larger surface area for heat to escape.

This can lead to higher energy bills and a colder home during winter months.

Insulating solid walls can significantly reduce heat loss, save money on your heating bills, and even prevent homes from becoming too warm in the summer.

Understanding the nature of solid walls is essential for selecting the right insulation method.

Solid walls are typically constructed using one or two layers of bricks without a gap in between that you would find in a cavity wall.

By identifying the type of walls in your home, you’ll be better equipped to choose the most effective insulation method and reap the rewards of an energy-efficient home.


Solid Walls and Energy Performance Certificate Ratings

By insulating the solid walls of an older property, either internally or externally, your property will acheive:

  • Thermal  insulation values similar to newer properties
  • Compliance with Part L of the building regulations.
  • EPC rating of a C which will meet the new forthcoming Minimum Energy Efficiency Standards (MEES)
  • Access to better interest rates with Green Mortage Lenders.
  • Lower energy bills.


Identifying Solid Walls

How can you determine if your home has solid walls?

One simple method is to observe the brick pattern on the exterior of your home.

Solid walls often have an alternating brick pattern with smaller ends visible, while cavity walls present an even pattern with bricks laid lengthways.

Additionally, if your home was built before 1920, it is likely to have solid external walls. Inspecting the width of your external walls can also provide insight – if the wall is less than 10 inches thick (250mm), it is probably solid.

Once you’ve identified the presence of solid walls, it’s time to explore insulation options.

Two primary methods for insulating solid walls are internal insulation and external insulation.

Each method has its advantages and disadvantages, with internal insulation typically being more cost-effective but less effective at retaining heat.

By understanding the unique features of your home’s solid walls, you can make an informed decision about the best insulation method for your needs.


Heat Loss in Solid Walls

Did you know that approximately 50% of the overall heat loss from a solid-walled property is attributed to the walls?

Insulating your solid walls is essential to address this significant heat loss and enjoy the benefits of a warmer, more energy-efficient home.

The right insulation materials can make a substantial difference in your home’s heat retention, with “breathable” or “vapour permeable” materials often recommended for traditional solid-wall buildings.

As you explore insulation options, remember that the goal is to create a barrier that prevents heat from escaping, keeping your home cosy and your energy bills in check.

Insulation Options for Solid Walls

A house with external wall insulation

Your journey to a warmer and more energy-efficient home begins with understanding the two primary insulation options for solid walls: internal wall insulation and external wall insulation.

Internal insulation requires fitting rigid insulation boards to the wall.

This can be done by constructing a stud wall, which is filled with insulation material.

This method is generally more cost-effective and can be implemented room by room.

External insulation, on the other hand, involves fixing a layer of insulating material to the exterior of the wall, providing improved insulation performance and potentially enhancing the appearance of the building.

Both internal and external insulation methods have their advantages and disadvantages, with factors such as installation costs, potential savings, and impact on living space playing a role in the decision-making process.

By weighing the pros and cons of each method, you can choose the best insulation option for your home and take a significant step towards a more comfortable and energy-saving living environment.


Internal Wall Insulation

Two common methods for internal wall insulation include fitting rigid insulation boards directly to the wall or constructing a stud wall filled with insulation material.

Rigid insulation boards, made from materials such as polystyrene or polyurethane, are easy to install and provide a high level of insulation.

Meanwhile, a stud wall approach may be more suitable for uneven walls or homes with damp issues, as it creates a small air gap between the outer wall and the insulation.

Internal wall insulation can be more cost-effective than external insulation, with a typical semi-detached house in the UK costing approximately £7,400 for installation.

However, it is crucial to consider the potential drawbacks, such as reduced interior space and possible moisture-related issues.

Ensuring proper moisture control and ventilation, as well as taking care to avoid thermal bridging, will help guarantee the effectiveness of the insulation and protect your home from potential damage.


External Wall Insulation

External solid wall insulation involves fixing a layer of insulation material to the exterior of the wall, using mechanical fixings and adhesive, and covering it with protective layers of render or cladding.

A wide range of finish options are available, including smooth, textured, painted, tiled, panelled, pebble-dashed, or brick slips, allowing you to choose a finish that matches your home’s aesthetic.

While external insulation can provide improved insulation performance and potentially enhance the appearance of your home, it is typically more expensive than internal insulation.

The cost of external insulation ranges from £100 per square meter for a small flat, up to £22,000 for a large detached house.

Despite the higher initial investment, external insulation may lead to a reduction in energy bills of up to 35%, making it a viable option for homeowners looking to make a long-term commitment to energy efficiency.

Costs and Savings Associated with Solid Wall Insulation

A house with Kingspan internal insulation Installing solid wall insulation can result in substantial savings on heating bills and improved home comfort levels.

To minimise installation costs, consider timing your insulation project with other home improvements or adopting a partial insulation and room-by-room approach.

In addition, research available financial assistance programs, such as the Energy Company Obligation (ECO) scheme and the Great British Insulation Scheme, which may offer grants or other support for insulation projects. With a clear understanding of costs and potential savings, you can make an informed decision to invest in solid wall insulation and enjoy the benefits of a warmer, more energy-efficient home.  

Internal Insulation Costs

  The cost of internal insulation can range from £90 to £120 per square meter, depending on the type of insulation material employed and the size of the area to be insulated. For a typical semi-detached house in the UK, the overall expenditure for internal solid wall insulation is approximately £7,400. Although internal insulation is generally less expensive than external insulation, it is crucial to consider factors such as reduced interior space and potential moisture-related issues when deciding which insulation method is best suited for your home.  

External Insulation Costs

  External insulation costs can vary widely, with prices ranging from £100 to £200 per square meter, depending on the type of insulation material and the size of the property. The typical cost of external insulation for a detached house will range from £15,000 to £20,000, a semi-detached house £8,000 to £10,000, and a mid-terrace is likely to be £6,000. While external insulation may be more expensive upfront, the potential energy savings and improved insulation performance may make it a worthwhile investment for homeowners seeking long-term energy efficiency.  

Potential Savings

  The potential savings associated with solid wall insulation depend on the size of the house and the type of insulation employed. According to the Energy Saving Trust, the estimated annual savings for a large detached home with solid wall insulation is £375. By comparing the potential savings with the initial investment, you can make an informed decision about whether solid wall insulation is the right choice for your home.

Reducing Installation Costs and Financial Support

A visual representation of solid wall insulation, which is a cost-effective solution for reducing installation costs

To reduce installation costs for solid wall insulation, consider timing the work with other home improvements or partially insulating your home.

By focusing on the most frequently used areas of your house and addressing the highest heat loss, you can minimise the amount of insulation required and lower the overall cost of the project.

Furthermore, investigate available financial assistance programs, such as the Energy Company Obligation (ECO) scheme and the Great British Insulation Scheme, which may offer grants or support for insulation projects.  

Timing Insulation with Other Home Improvements

  One way to minimise installation costs of solid wall insulation is to coordinate it with other home improvements, such as repainting or installing a new bathroom or kitchen. By consolidating projects, you can avoid additional labor costs and decrease the overall expense of your insulation upgrade. Additionally, ensure your installer is protected by an applicable 25-year guarantee for added peace of mind.  

Partial Insulation and Room-by-Room Approach

  Adopting a partial insulation and room-by-room approach can help mitigate the costs of solid wall insulation projects. By concentrating on the parts of your home that are used most often and where heat loss is the most significant, you can reduce the amount of insulation required and consequently decrease the overall cost of the project. This method allows you to prioritise your home’s insulation needs while still working within your budget.  

Financial Assistance Programs

  Several financial assistance programs are available to help offset the costs of insulation projects. The Energy Company Obligation (ECO) scheme and the Great British Insulation Scheme are government-backed programs that offer grants for insulation and other energy-saving measures. Eligibility requirements for grants typically depend on homeowners’ income and property criteria. By exploring these programs, you can potentially receive financial support that makes your insulation project more affordable.

Important Considerations for Solid Wall Insulation

A house with moisture control and ventilationWhen planning a solid wall insulation project, it is crucial to consider factors such as the type of insulation material, internal or external insulation, moisture control, and potential impact damage to certain finishes.

Properly addressing these considerations will not only ensure the efficacy of your insulation, but also protect your home from potential damage.

Additionally, consider other insulation options, such as loft insulation and potential heating upgradws, to further improve your home’s energy efficiency.

Moisture control and ventilation play a pivotal role in the success of any insulation project.

Proper ventilation ensures that the insulation is installed accurately and does not cause harm to the property.

It is essential to leave a suitable air gap (approximately 1 inch) between the insulation material and the exterior walls to allow the walls to ‘breathe’ and prevent damp or condensation from accumulating on the interior walls of the property.

Before commencing any insulation project, it is imperative to ensure that there is no existing damp in the walls. Failure to address dampness can exacerbate the issue and cause further damage to your home. By prioritising moisture control and ventilation, you can protect your home from potential damage while enjoying the benefits of improved insulation.

DIY vs Professional Installation

A house with building regulations and planning permissionWhile DIY installation may seem like an attractive option for internal wall insulation, it is generally not recommended for solid wall insulation due to the complexity and potential hazards of the task.

Professional installation is more prevalent and typically more efficient.

By enlisting the services of an experienced installer, you can ensure that your insulation project is completed to the highest standard and avoid any potential risks associated with DIY installation.

Building Regulations and Planning Permission

Before embarking on a solid wall insulation project, it is important to consult relevant building regulations and obtain planning permission if necessary.

External wall insulation must comply with the requirements of Building Regulations (Part L) to ensure walls have U-values of no more than 0.3 W/m2K.

In most cases, planning permission is not required for external wall insulation, except for homes located within Conservation Areas, Areas of Outstanding Natural Beauty, or listed buildings.

By adhering to building regulations and obtaining planning permission, you can avoid potential legal issues and ensure a smooth insulation project.

Additional Home Insulation Ideas

A house with heat pump innovationsBesides solid wall insulation, there are several other insulation options to consider for improving your home’s energy efficiency.

Insulating the loft , cavity walls, and floors can make a significant difference in your home’s heat retention and energy consumption.

Making Your Home Heating Greener

By exploring renewable energy sources, such as solar power, solar heating, air source heat pumps, and wind energy, you can make your home heating system more environmentally friendly.

Adopting renewable energy solutions can not only reduce your carbon footprint, but also lead to long-term savings on your energy bills.


Heat Pump Innovations


Recent advancements in heat pump technology have resulted in improved efficiency, noise reduction, and integration with smart home technology. New compressors, variable-speed compressors, and innovative designs have made heat pumps more effective and suitable for a wider range of conditions.

Additionally, research and development efforts have focused on making heat pumps more affordable and simpler to install. By staying informed about the latest heat pump innovations, you can ensure that your home heating system remains at the cutting edge of energy efficiency and sustainability.


Stop guessing EPC rating


In conclusion, solid wall insulation is a major contributer in creating a warmer, more energy-efficient, and eco-friendly home.

By understanding solid walls, exploring internal and external insulation options, and considering important factors such as moisture control and ventilation, you can make informed decisions to improve your home’s insulation and reduce your energy bills.

Additionally, by investigating renewable energy sources and staying up-to-date on heat pump innovations, you can further enhance your home’s energy efficiency and contribute to a greener future.

Don’t let your hard-earned money slip through the cracks – take action today and invest in solid wall insulation for a more comfortable and sustainable home.


Frequently Asked Questions

What is the best type of wall insulation?

For optimal insulation, rigid foam insulation is the best type of wall insulation, such as Kingspan, Celotex, Ecotherm etc.

Made of polyurethane, foam insulation is highly effective at blocking heat and providing soundproofing and air sealing.

It also has a low environmental impact, making it an ideal choice for those looking for eco-friendly solutions.

Additionally, it’s easy to install and relatively cost-effective compared to other types of insulation.


What does solid wall insulation do?

Solid wall insulation acts as an effective barrier to the elements, preventing air flow in and out of your walls and creating a more comfortable living space.

It helps protect your walls from moisture and temperature changes, extending the life of the brickwork and improving indoor air quality.

In addition, it reduces energy bills by reducing heat loss and minimising draughts.


How long does solid wall insulation last?

Solid wall insulation is designed to last around 30 years, providing an effective solution for reducing energy costs and preventing heat loss over a long period of time.

It is an ideal choice for those looking for a long-term solution to their energy efficiency needs. It is also a great way to reduce your carbon footprint and help the environment.

The installation process is relatively straightforward and can be done easily.


What is the definition of a solid wall?

A solid wall is a single external wall made of either two bricks wide or stone without a gap or cavity. It is distinct from a cavity wall, which is comprised of two layers, separated by a hollow space (cavity) and made of masonry such as brick or cinder block.

Masonry absorbs rainwater and humidity, allowing it to slowly enter the wall.

source: https://en.wikipedia.org.wiki/Cavity_wallCavity wall – Wikipedia provides strong insulation and protection against the elements.


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Lewis Dickson
Written by Lewis Dickson