External Wall Insulation (EWI) is a highly effective way to improve the energy efficiency of your home by reducing heat loss and keeping your home warmer in winter and cooler in summer. By applying an insulating layer to the outside of your property, external wall insulation can help lower energy bills and increase the overall comfort of your home.
For those looking for a quick estimate, the average cost for high-quality external wall insulation ranges from £75 to £150 per square metre depending on factors such as material choice, property size, and installation complexity. The actual cost will vary based on the specifics of your home, the type of insulation chosen, and any additional work required, such as rendering or cladding.
In this guide, we will explore the factors that influence the cost of EWI, provide a detailed cost breakdown for different material types, and explain how to calculate the overall investment for your home. We will also look at potential savings and government grants to reduce costs.
How Much Does External Wall Insulation Cost Per Square Metre?
The cost of external wall insulation is influenced by the material used, the size of the property, and the complexity of the installation. Below is a comparison of common insulation materials and their associated costs per square metre:
| Material Type | Average Cost per m² | Thermal Efficiency (U-Value) | Lifespan |
|---|---|---|---|
| EPS (Expanded Polystyrene) | £25 – £50 | 0.038 W/m²K | 30-40 years |
| Mineral Wool (Rockwool) | £35 – £60 | 0.035 W/m²K | 30-40 years |
| PIR (Polyisocyanurate) | £40 – £75 | 0.022 W/m²K | 40+ years |
| Phenolic Boards | £50 – £80 | 0.022 W/m²K | 40+ years |
| Wood Fibre | £60 – £100 | 0.045 W/m²K | 30-40 years |
Ballpark Cost Ranges
- Low-End (EPS, Rockwool): These materials are more affordable but have slightly lower thermal efficiency compared to premium options. For a 3-bedroom house, the cost could range from £5,000 to £8,000 for complete installation.
- Mid-Range (PIR, Phenolic Boards): These are more efficient, providing better thermal performance and longer lifespan, with costs ranging from £8,000 to £12,000 for a 3-bedroom home.
- Premium (Wood Fibre, High-Performance Boards): These materials are excellent for eco-conscious homeowners and those seeking the highest thermal performance. Expect to pay £12,000 to £15,000+ depending on the size and complexity of the installation.
Factors That Influence EWI Costs
Several factors contribute to the overall cost of external wall insulation. Understanding these will help you get a clearer picture of what to expect and ensure you’re prepared for the investment.
Property Size & Type
The size of your property plays a key role in the cost of EWI. Larger homes will require more insulation, increasing the total cost. Additionally, the type of property (detached, semi-detached, terraced) can affect the installation complexity. For example, corner properties or properties with intricate designs may cost more to insulate due to the increased need for scaffolding and additional work.
Wall Surface Condition & Preparation
The condition of your walls is another factor that will impact the cost. If the walls are in poor condition, such as having cracks, damp issues, or require extensive preparation (e.g., cleaning or repairing), the installation will be more expensive. Preparing the surface and fixing any issues beforehand can add to the overall cost.
Labour & Installation Complexity
The cost of labour depends on your location and the complexity of the installation. For example, areas with a higher cost of living may have higher labour rates. If your home requires scaffolding, rendering, or additional features such as cladding, this can also add to the cost.
Additional Work (Cladding, Rendering, Fixings, Paint)
External wall insulation typically requires additional work such as rendering (applying a protective layer over the insulation) and cladding (adding decorative or protective material to the exterior). Cladding and rendering can increase the overall price, as can adding a finishing paint or texture to the exterior. Depending on the materials chosen, this can add a few thousand pounds to the final cost.
Grants & Financial Support
There are various government grants for external wall insulation available that can help offset the cost. These schemes are available to eligible homeowners and can cover a percentage of the installation cost, reducing the overall investment needed.
How Much Does it Cost to Insulate Different Parts of a Home?
Wall Insulation Cost
The cost of insulating walls varies depending on the type of wall construction (solid, cavity, or timber frame). Solid walls generally require external wall insulation, while cavity walls can be insulated more cheaply with cavity wall insulation.
- Solid Walls: Insulating solid walls can cost between £8,000 and £12,000 for a typical 3-bedroom house.
- Cavity Walls: Cavity wall insulation costs around £2,500 to £5,000 for a 3-bedroom home.
Roof Insulation Cost
Loft and roof insulation are an essential part of the overall thermal efficiency of your home. The cost of insulating a loft or pitched roof can range from £1,500 to £3,500, depending on the size of the area and the materials used.
Floor Insulation Cost
Floor insulation is important for homes with suspended timber floors or solid floors. Prices for suspended timber floor insulation generally range from £2,500 to £5,000, while solid floor insulation can cost around £3,000 to £6,000.
Material Price Breakdown
Here’s a breakdown of common materials used for external wall insulation and their associated costs:
| Material | Best Use Case | Cost per m² | Lifespan |
|---|---|---|---|
| Rockwool (Mineral Wool) | External walls, lofts | £35 – £60 | 30-40 years |
| EPS (Expanded Polystyrene) | External walls, low-cost insulation | £25 – £50 | 30-40 years |
| PIR (Polyisocyanurate) | External walls, energy-efficient insulation | £40 – £75 | 40+ years |
| Wood Fibre | Eco-friendly insulation for external walls | £60 – £100 | 30-40 years |
Is External Wall Insulation Worth the Investment?
The decision to install external wall insulation should be based on both the upfront cost and long-term benefits. Over time, external wall insulation can lead to significant energy savings, with estimates suggesting reductions of up to 40% on heating bills. The return on investment (ROI) is typically seen within 5-10 years, depending on your energy usage and insulation material.
Additionally, homes with high-quality insulation have higher market value and appeal to potential buyers looking for energy-efficient homes. This can help you recover some of the installation costs when it’s time to sell. Weigh up the over time savings and increased property value against the costs to help you understand if external wall insulation is worth it. You should seek professional advice before making a decision.
Are There Grants Available to Reduce Costs?
Yes, there are several government-funded schemes that can help reduce the cost of external wall insulation. These grants are particularly beneficial for low-income households or those in certain geographic areas.
| Scheme Name | Eligibility | Coverage Amount |
|---|---|---|
| Great British Insulation Scheme | Low-income households | Up to £10,000 |
| ECO4 (Energy Company Obligation) | Low-income or vulnerable residents | Subsidised insulation |
| Local Authority Grants | Varies by region | Varies |
You can apply for these grants through energy suppliers, local councils, or online government portals, which will assess your eligibility and guide you through the application process.
How Often Should External Wall Insulation Be Replaced?
On average, external wall insulation should be replaced after 30-40 years, depending on the material. However, regular inspections are necessary to ensure that the insulation remains effective. Signs that your insulation may need to be replaced include noticeable damage, cracks, or a significant reduction in thermal efficiency.
Conclusion
The cost of external wall insulation can vary depending on the material used, the size and type of your property, and additional work such as rendering or cladding. On average, you can expect to pay between £5,000 to £15,000 for a 3-bedroom home, with potential energy savings and long-term benefits to offset the upfront cost.
With government grants available to reduce the cost and significant long-term energy savings, external wall insulation is a solid investment for homeowners looking to improve energy efficiency and comfort. If you’re considering EWI for your home, it’s a good idea to get a free quote from a professional installer to better understand the costs specific to your property.
FAQ’s
- What is the cheapest option for external wall insulation?
EPS (Expanded Polystyrene) is generally the cheapest option for external wall insulation. - Can EWI reduce condensation and damp?
Yes, by regulating the internal temperature and preventing moisture from escaping, EWI can help reduce condensation and damp. - Does adding EWI affect my house’s EPC rating?
Yes, EWI can improve your home’s EPC rating by significantly reducing energy consumption and increasing thermal efficiency.
Writer’s Summary
Owen O’Callaghan is passionate about sustainability and energy efficiency, with a particular focus on external wall insulation. He is dedicated to helping homeowners understand the long-term benefits of energy-saving solutions, particularly in reducing heating costs and improving home comfort. Owen’s interest lies in promoting environmentally friendly practices that not only help reduce energy bills but also contribute to a more sustainable future for both homeowners and the planet.
