WHAT IS EWI (External Wall Insulation)?

EWI (External Wall Insulation) involves fixing insulation boards to a property’s exterior walls and covering them with a protective render finish. This helps keep the building warmer, reduces energy bills and improves its appearance.

WHAT ARE SOME OF THE EWI INSULATION SYSTEMS?

The most commonly used for EWI in the UK are:

1. EPS (Expanded Polystyrene) – Lightweight and cost-effective (read more about this system)
2. Kingspan (Phenolic Insulation) – High-performance insulation with thinner boards (read more about this system)
3. Mineral Wool (Rockwool) – Fire-resistant, breathable and provides good sound insulation (read more about this system)

WHAT ARE THE BENEFITS OF EWI?

• Improved Energy Efficiency – Reduces heat loss and helps lower energy bills.
• Warmer Home – Keeps your property warmer in winter and more comfortable in summer.
• Improved Appearance – Gives external walls a fresh, modern finish.
• Weather Protection – Helps protect external walls from rain and harsh weather.
• Reduced Condensation – Can help reduce condensation and damp caused by cold walls.
• Improved Sound Insulation – Can reduce outside noise, depending on the insulation used.
• Increased Property Value – May improve your property’s appeal and value.
• Long-Lasting Finish – Provides a durable exterior when correctly installed and maintained.

PRACTICAL ASPECTS OF EWI:

Over the years, we have found that some of our new clients were not made aware of the practical considerations involved in installing external wall insulation (EWI). In some cases, this has contributed to the render system failing over time.

1. It is important to understand that external wall insulation increases the thickness of your walls. Therefore, roof overhangs, window sills and other projections must provide sufficient coverage to protect the insulation and render system from water damage.
2. As external wall insulation increases the thickness of your walls, downpipes, cables, gutters and other external fixtures may need to be temporarily removed or repositioned to accommodate the new insulation and render system. This helps ensure a neat finish and prevents potential issues with water drainage.

WHAT ARE THE STEPS:

1. Scaffolding – Usually required to access external walls safely.
2. Wall Preparation – Walls must be clean, sound and suitable for insulation.
3. Insulation Boards – EPS, mineral wool or phenolic boards are fixed to the walls.
4. Wall Thickness – Insulation increases the thickness of external walls.
5. Windows and Doors – Reveals, sills and surrounding details may need adjusting.
6. Pipes and Gutters – Downpipes, cables and external fixtures may need repositioning.
7. Roof Overhangs – Must provide enough coverage to protect the insulation.
8. Rendering – Apply a reinforced base coat and decorative finish.
9. Weather Conditions – Installation requires suitable temperatures and dry conditions.
10. Installation Time – Depends on the property’s size, condition and complexity.
11. Maintenance – Occasional cleaning and repairs help maintain the finish.

Please note that the above is a general outline of the installation process. Each property has different requirements, so the steps involved may vary depending on the condition and structure of the building.

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