Have you ever wondered how to make your home warmer, more energy-efficient, and better protected against the rain and wind? For many homeowners, External Wall Insulation is the answer.
Whether you’re looking to cut energy bills, reduce damp and condensation, or simply modernise your home’s appearance, EWI offers a range of benefits that go beyond just insulation. But how does it work, what’s involved, and is it really worth the investment?
In our blog ‘What Is EWI and Why Is It Worth Considering?’, we’ll go over everything you need to know about external wall insulation – from the materials used and how it’s installed, to the buildings it’s suitable for and the long-term benefits it provides.
Content Page
- What Is EWI and Why Is It Worth Considering?
- Most Popular Insulation Materials
- What makes up an EWI System?
- What Buildings Can EWI Be Installed On?
- Why External Wall Insulation is Important?
- Do I Need Planning Permission For Installing EWI in the UK
- What is the cost of EWI?
What Is EWI and Why Is It Worth Considering?
External Wall Insulation is a type of insulation system that involves applying two layers to the external walls of your home. The first is an insulating layer that helps retain heat, and the second is a protective render that shields against weather and offers a decorative finish. The top layer (render) allows you to customise the colour, texture, and finish, giving your property a refreshed, modern appearance.
Most Popular Insulation Materials
There are many different insulation materials that can be used as part of the system, the most common materials used in the UK are:
Mineral Wool: Made from natural or recycled materials, mineral wool is known for its fire resistance and soundproofing qualities. It’s breathable, allowing moisture to escape, which helps prevent damp issues. Mineral wool typically requires a thickness of around 110mm to meet the required U-value. Mineral wool insulation is an excellent choice for multi-storey buildings.
Expanded Polystyrene (EPS): This material is lightweight and budget-friendly. It has excellent thermal insulation properties and is resistant to moisture, making it ideal for energy efficiency. EPS boards typically require a thickness of around 90mm for optimal thermal efficiency and for achieving a U-value of 0.30 W/m²K to comply with building regulations in the UK.
Phenolic Foam: Phenolic Foam is a high-performance insulation material with a low thermal conductivity. It’s lightweight, very durable, and offers excellent fire resistance. A 60mm layer is sufficient to meet the necessary U-value.
What makes up an EWI System?
EWI systems are designed to be breathable, allowing moisture from within the walls to escape while preventing external water from penetrating. This helps reduce the risk of damp and mould. An EWI system is made up of several key components that work together to save energy and protect your home.
The graphic below illustrates the layers that make up an EWI system.
What Buildings Can EWI Be Installed On?
EWI is ideal for buildings with solid walls, which are common in homes built before the 1920s. These walls are typically made from a single or double layer of brick or stone with no cavity in between. EWI is also suitable for concrete-built properties and those with timber or steel frames. It’s vital to remember that EWI should be fitted by a specialist installer.
Why External Wall Insulation is Important?
From cutting heat loss to contributing to sustainability, here are the key reasons why investing in EWI is a smart choice for any homeowner.
Reduces Heat Loss: Did you know that up to 35% of a building’s heat is lost through uninsulated walls? EWI provides a solution by creating a thermal barrier that reduces heat transfer, keeping indoor temperatures consistent. By sealing cracks and gaps, EWI minimises drafts and significantly improves energy efficiency. To ensure the best results, proper installation is key, particularly in tricky areas like corners and around meter boxes.
Cuts Energy Bills: By improving thermal efficiency, EWI reduces the energy required to heat or cool a home. This translates into lower energy bills, making it a cost-effective solution over time.
Prevents Condensation: EWI helps minimise condensation on internal walls, reducing the risk of mould growth and improving indoor air quality. It also protects external walls from rain and dampness, which can cause structural damage over time.
Improves Property Appearance: An EWI system combined with a fresh render can transform the look of a property and improve its curb appeal. The final waterproof render or decorative finish can be textured, coloured, or patterned to suit your aesthetic preferences, while also protecting the insulation and walls from weather elements like rain, wind, and UV radiation.
Can Increase Property Value: Energy-efficient homes are more appealing to buyers, especially in today’s increasingly environmentally-friendly world. EWI not only boosts a property’s energy performance rating but also adds long-term value by modernising the exterior and reducing maintenance needs.
Offers Fire Resistance: Certain insulation materials used in EWI systems, such as mineral wool, provide improved fire resistance, contributing to enhanced safety.
Minimal Disruption: Since EWI is applied to the exterior walls of your property, the installation process causes minimal disruption to your daily life, unlike some internal insulation methods.
By addressing heat loss, reducing energy bills, and improving both comfort and aesthetics, EWI is a valuable investment for any property. It’s a long-term solution that not only benefits the homeowner but also contributes to a more sustainable future.
Do I Need Planning Permission For Installing EWI in the UK
In most cases, installing EWI or adding a new render finish doesn’t require planning permission, as long as it doesn’t significantly alter the external appearance of your home. However, if your property is listed or located in a conservation area, planning permission may be required. It’s always a good idea to check with your local planning authority to be sure.
What is the cost of EWI?
The cost of EWI depends on several factors, including the size of your property, the type and thickness of insulation chosen, and any repairs needed before installation. On average, the costs are approximately:
- Mid-Terrace House: £5,000 to £10,000
- Semi-Detached House: £8,000 to £15,000
- Detached House: £15,000 to £25,000
While EWI requires a significant upfront investment, it can result in substantial energy savings over time, making it a cost-effective choice in the long run.
In the UK, grants are available to make EWI more affordable, particularly for households with lower incomes. These include the Great British Insulation Scheme (GBIS) and The Energy Company Obligation (ECO4). These grants may partially or fully cover the cost of installation.
The specific grants and eligibility criteria vary, so it’s important for homeowners to research their options and consult their local authority or an approved installer for more details.
Overall, EWI is an excellent solution for improving the energy efficiency and thermal performance of solid wall buildings, while also improving their appearance. This makes EWI a valuable, long-term investment. To maximise its benefits, it’s essential to work with a qualified and experienced installer as proper installation is crucial to avoid issues such as cold bridging, mould growth, and draughts, ensuring your home stays warm, efficient, and comfortable.
For expert advice on External Wall Insulation and how to improve your home’s energy efficiency, get in touch with our specialists today.
