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How to Insulate Walls Without Cavity? 2025 Guide
- The cost of non-cavity wall insulation typically ranges from £7,500 to £12,000, depending on the method, the size of your home, and the insulation material selected.
- For solid walls, you can choose between internal and external insulation based on your budget and personal preference.
- Installing non-cavity wall insulation can boost your property’s value by up to 14%, significantly reduce energy bills, and last between 25 to 40 years, depending on the method used.
Cavity wall insulation in the UK is among the most effective and widely used methods for insulating walls. With over 71% of UK homes benefiting from cavity wall insulation, it can reduce heat loss by up to 33%, leading to annual energy savings of nearly £405 for a detached home.
While many homes in the UK benefit from cavity wall insulation due to its advantages, some properties still lack cavity walls. In such cases, you might wonder how to insulate walls without a cavity. Luckily, several alternatives to cavity wall insulation, such as internal or external wall insulation, can effectively improve your home's energy efficiency.
In this WhatCost guide, we’ll explore how to insulate your walls without a cavity, the associated costs, and the benefits of these types of insulation for your house. We can also help you connect with reliable installers in your area. Rather than spending hours researching professionals, contacting companies, and comparing quotes, let us handle the hard work for you.
Complete our quick 30-second form, and WhatCost will connect you with up to four free quotes from top-rated insulation specialists in your area—no hidden costs and no obligations. Click below to get started!
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How to insulate walls without cavity in the UK
Understanding how to insulate walls without a cavity is crucial for improving thermal efficiency and reducing energy bills. Unlike cavity walls, which have a single insulation method, solid wall insulation offers two distinct options, each with advantages and disadvantages.
Before exploring the best ways to insulate a house with no cavity, it’s essential to identify whether your walls are solid or cavity. This process is straightforward, especially if the brickwork on your home is visible. For solid walls, the bricks are typically arranged in a uniform pattern. In contrast, cavity walls often feature a stretcher bond design.
Homes built before the 1920s are more likely to have solid walls. However, the most accurate way to determine your wall type is to consult an insulation specialist. Once you’ve confirmed that your walls are solid, you can select the most effective solid wall insulation method to enhance your home’s thermal efficiency.
Internal wall insulation
Internal wall insulation involves adding a layer of insulating material to the interior side of your home's existing walls. This can be achieved by either attaching rigid insulation boards directly to the wall or constructing a stud wall filled with insulation material. Once the insulation is installed, a layer of plasterboard can be applied to create a smooth, finished surface, ready for painting or wallpapering.
The process typically includes the following key layers:
- Existing wall surface: The original interior wall, usually made of brick, stone, or another material.
- Vapour control layer: A crucial barrier that prevents moisture buildup, helping to reduce the risk of condensation and dampness.
- Insulation layer: The primary thermal barrier, designed to reduce heat loss effectively.
- Plasterboard or internal finish: The final layer, often plasterboard, which provides a smooth, decorative surface for a polished appearance.
External wall insulation
External wall insulation is applied to the outside of your home, making it ideal for properties with solid walls. This method involves multiple layers, each serving a specific purpose:
- Adhesive layer: Applied directly to the external wall, this layer ensures the insulation panels are securely bonded.
- Insulation board: The primary insulating component, it acts as a thermal barrier, reducing heat loss by insulating the home from the external environment.
- Reinforcement layer: Provides added strength and durability to the system, protecting it against cracks and damage.
- Fixing anchors and glass mesh: The anchors securely hold the insulation boards in place, while the glass mesh adds structural stability.
- Primer: This layer waterproofs the insulation system, evens out the surface, and prepares it for the final coat.
- Finishing render layer: The outermost layer enhances the building's appearance while shielding it from weathering, UV rays, and physical damage. This render or cladding provides both aesthetic appeal and long-lasting protection.
Selecting the ideal solid wall insulation method depends on your home’s requirements, your personal preferences, and your budget. To find the best solution for you, it’s important to consult with a qualified insulation specialist in your area.
How much does it costs to insulate walls without cavity
The cost of insulation for non-cavity walls can range between £7,500 to £12,000. This price varies based on your home's size, the chosen insulation method, and the type of insulation material used.
External wall insulation is generally more expensive due to its complexity and the additional layers required, such as adhesive, reinforcing mesh, render, and a finishing layer, all of which increase material costs. On the other hand, internal wall insulation is a more affordable option because the installation process is more straightforward and involves fewer materials. However, a key drawback of internal wall insulation is that it reduces the internal living space.
Labour costs for insulation specialists usually average around £250 per person per day. For larger properties or homes with complex architectural features, irregular shapes, or multiple stories, labour costs will increase as the job requires more time. Additionally, labour charges may be higher in larger cities where the cost of living is greater.
The type of material you choose for non-cavity wall insulation significantly impacts the total cost. Below are the prices of the most commonly used wall insulation materials in the UK:
| Material | Average cost per m2 |
|---|---|
| EPS boards | £10 |
| PIR boards | £12.50 |
| Mineral (Rock) wool | £18.20 |
| Woodfibre | £19 |
| Cork board | £19.50 |
| XPS boards | £21.50 |
Non-cavity wall insulation can be expensive, but insulation grants can ease the financial burden. Working with a certified insulation installer is necessary to qualify for these grants.
At WhatCost, we make it straightforward by connecting you with up to four free quotes from highly rated-insulation specialists in your area. Complete our quick 30-second form now to get started. Don’t wait—click below to seize this opportunity!
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Pros and cons of non cavity wall insulation
Non-cavity wall insulation, which includes external wall insulation and internal wall insulation, offers numerous benefits but also comes with certain drawbacks. Here’s an overview of the combined pros and cons to help you decide on the best option for your home.
Pros
- Improved energy efficiency: Both external and internal insulation methods reduce heat loss, lowering energy bills and keeping your home warmer. External insulation can save between £140 and £700 annually.
- Increased property value: Insulating your home can raise its EPC rating, increasing its market value by up to 14%.
- Weather protection: External insulation protects against dampness and weathering, extending the lifespan of your walls.
- Soundproofing: Both methods can help reduce noise, with external insulation particularly effective in noisy urban or roadside environments.
- Preserved exterior or interior appearance: Internal insulation maintains the external look of your home, ideal for conservation areas, while external insulation can improve curb appeal by refreshing the façade.
- Durability: Both methods offer long-term benefits when properly installed, with internal insulation lasting up to 25 years and external wall insulation lasting up to 40 years.
Cons
- High cost: External wall insulation is more expensive than internal, and additional layers like adhesive, reinforcing mesh, render, and finishing materials drive up costs.
- Disruption during installation: Both methods involve disruption—external insulation may require scaffolding and restrict access to certain areas. In contrast, internal insulation can temporarily render rooms unusable.
- Loss of interior space: Internal insulation reduces room size, with walls losing an average of 100 mm.
- Moisture risks: Both methods can lead to damp issues if improperly installed, especially when using non-breathable materials or neglecting vapour barriers.
- Planning permission: External insulation may require planning approval, particularly for homes in conservation areas or with unique architectural features.
- Impact on fixtures: Internal insulation requires removing and reinstalling fixtures like radiators, electrical outlets, and skirting boards, reducing time and costs.
By weighing these pros and cons, you can make a well-informed decision about the insulation method that best aligns with your home, budget, and needs. Solid wall insulation offers significant benefits, particularly for older UK homes, but careful planning is essential. Consulting with a professional is the best way to determine the most suitable solution for your specific property.
At WhatCost, we confidently connect you with the top insulation professionals in your area. Complete our quick 30-second form, and you’ll receive up to four free quotes with no hidden costs and absolutely no obligation. Click below to discover how we can help you!
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