Facts & Myths about External Wall Insulation

Facts & Myths about External Wall Insulation

External Wall Insulation (EWI) systems have become increasingly popular lately as both homeowners and businesses aim to enhance their building's energy efficacy and cosiness. Yet, EWI isn't a recent innovation – it originated in Germany and has been implemented across Europe since the 1960s. Thus, it stands as a tried-and-true solution for elevating the thermal capabilities of older structures and ensuring superior thermal performance in new constructions.

External Wall Insulation in a Nutshell

EWI is an integrated system that, put plainly, involves a substantial layer of insulation positioned between a wall's outer surface and the building's exterior finish, which can be directly added onto the insulation. It's also worth noting that EWI might be termed ETICS, denoting External Thermal Insulation Composite Systems, or SWI, an abbreviation for Solid Wall Insulation.

The benefits of External Wall Insulation are undeniable. However, after 15 years in the External Wall Insulation industry, we've encountered a myriad of misconceptions. As with any trade, myths abound, and it's crucial to differentiate fact from fiction for homeowners and professionals alike. In this blog, our EWI specialists will clarify all misunderstandings by providing you with a comprehensive list of the most common myths about External Wall Insulation, paired with the realities.

Myth: EWI makes homes look unattractive

Fact: Many believe that EWI systems give properties a chunky and unappealing look. However, in reality, External Wall Insulation systems can significantly rejuvenate the exterior of a home, both in design and structural presence. Far from being a visual downgrade, EWI can elevate the visual charm of a residence. With an extensive variety of finishes on offer – from straightforward rendered styles to brick-like textures or ornamental tiles – homeowners have the opportunity to both contemporise their property's appearance and boost its energy efficiency.

Myth: EWI Is Only For Older Homes

Fact:  While many older properties can greatly benefit from EWI due to their lack of adequate insulation, the belief that External Wall Insulation is only suitable for older properties is a common misconception. In reality, modern homes can also see improvements in thermal comfort and energy efficiency with the right EWI system. It's about addressing the specific needs of the building, regardless of its age. 


Key benefits of adding External Wall Insulation to new buildings include:

  • Elevated Energy Ratings: While newer homes often boast decent energy ratings, EWI can further optimise this, ensuring optimal energy conservation.

  • Meeting Regulatory Standards: As building codes become stricter, advocating greater energy efficiency, EWI provides homeowners a step ahead, ensuring their homes meet future requirements.

  • Aesthetic Versatility: Current homes can tap into the diverse range of looks EWI offers. Be it a sleek modern finish, a countryside vibe, or any style in between, there's an EWI finish to match every architectural vision.

  • Advancing Eco-friendly Living: As the focus on sustainable living and minimising energy use intensifies, choosing EWI represents a forward-leaning decision for homes, regardless of their age.

  • Enhancing Property Worth: Integrating EWI can often elevate a home's market value. A home that's both energy-efficient and visually striking is naturally more enticing to potential buyers, marking it as a wise long-term choice.

Myth: External Wall Insulation can trap dampness and cause mould issues inside.

Fact: Kind of the opposite- a professionally installed EWI system incorporates adequate ventilation measures to ensure that any moisture generated inside the home (from cooking, showering, etc.) can escape. External Wall Insulation raises the surface temperature of walls, reducing the temperature difference between the inside and outside. This prevents condensation and mould growth. 

Moreover, the insulation layer also prevents cold bridging, where cold spots occur on internal walls, which can be a common area for condensation to form.  In essence, there's no basis to believe that EWI with a breathable render (e.g. Lime render) would induce mould. Nevertheless, it's crucial to maintain proper ventilation by regularly opening windows and utilising extractor fans in high-moisture areas like kitchens and bathrooms.

How Does EWI Moisture Mechanics Work?


  • Ventilation Capabilities: Top-notch EWI systems are crafted to permit ventilation. This ensures that they let water vapour transition through, allowing any internal moisture to dissipate from the walls, thereby avoiding damp accumulation.

  • Water Resistance: The outer coatings employed in EWI, notably contemporary silicone renders, possess water-repellent properties. They fend off rain, ensuring it doesn't infiltrate the insulation layer or the wall beneath.


How Does External Wall Insulation Control Condensation?

  • Diminished Cold Areas: EWI, by insulating the exterior walls, curtails temperature variances on the inside wall surfaces. This lessens the chances of condensation, which, if left unchecked, can result in damp and mould formation.

  • Balancing Indoor Moisture Levels: When EWI systems are fitted correctly, they assist in sustaining ideal indoor humidity, further curtailing the potential for condensation.

Myth:  Installing EWI will cause major disruption to my daily life.

Fact: While any construction work involves some level of disturbance, professional EWI installers work to minimise this as much as possible. Typically, work is carried out externally, meaning internal disruption is limited. Before beginning their work, constructors always conduct a comprehensive assessment of the property. This ensures a smoother installation process as potential challenges can be detected at an early stage. With efficient planning and communication, homeowners can carry on with their daily routines with minimal interruptions.


How Long Does External Wall Insulation Take?

How long the installation takes primarily hinges on the property's size and the intricacy of its architecture. More straightforward, compact homes might be done in just a few days, but bigger houses with detailed features could stretch the timeframe.

External elements, like the weather, can also play a role in the pace of the job. Although certain state-of-the-art EWI materials are suited for various weather scenarios, particularly adverse conditions might cause brief hold-ups.

Myth: EWI Systems Are Too Expensive and Not Worth the Investment.

Fact: EWI might seem like a significant investment upfront, but the long-term savings on energy bills justify the cost. Moreover, quality EWI systems are designed to last for decades. Over time, the energy savings can offset the installation costs, and homeowners can even see a positive return on investment. A well-insulated home reduces heat loss from a property, requiring less energy for heating and often has improved Energy Performance Certificate (EPC) ratings.

Myth: External Wall Insulation Only Works In Cold Climates

Fact: Many hold the view that EWI systems are most effective in chillier climates, aiming predominantly to minimise heat escape through walls. Yet, not only do they provide warmth in the winter, but they also offer a cooler ambience in the summertime. Efficiently installed insulation acts to decelerate the transfer of heat between spaces, ensuring a pleasant indoor temperature regardless of external conditions. Should you rely on an air conditioner in the warmer months, you'll observe energy savings, much like you would when using your heating system in colder seasons.

Myth: I can use any material to insulate my house


Fact: It is another common myth we’ve encountered in our 15 years in the industry. The insulation chosen largely hinges on its intended use and the home's structure. Implementing the wrong insulation material could harm the property and won't function as expected. The selected insulating material also requires careful consideration. Collaborating with a knowledgeable supplier and contractor, who recognises the significance of selecting the appropriate insulation for every situation, is vital. Your ultimate choice should consider not just the cost but also the product's quality and its demonstrated long-term efficacy.


After 15 years in the field, we can confidently say that a properly installed EWI system is a valuable asset to any property. External Wall Insulation provides a host of advantages, including enhanced energy efficiency, heightened comfort, and a diminished carbon footprint. By addressing the prevalent myths about EWI systems, we aim to persuade more homeowners and businesses to explore this potent method for enhancing their properties.

It's about understanding the facts and trusting experienced professionals to guide you through the process. Don't let myths deter you from enhancing your home's comfort, appearance, and energy efficiency. 

And if you need more information about the EWI system, contact our qualified contractors today! 




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