External Wall Insulation: Non-Invasive Way To Insulate Your House

Upgrading your home’s energy efficiency doesn’t have to mean sacrificing internal space or enduring disruptive renovations. For homeowners across the UK looking to cut heating bills, reduce carbon footprint, and modernise their property’s appearance, External Wall Insulation (EWI) is the ultimate solution.

With high-performance systems, fire safety compliance, and stunning finish options like brick slip cladding or coloured render, EWI provides thermal efficiency without touching internal walls—and Vergolus is the UK’s rising leader in this space.

What Is External Wall Insulation?

External Wall Insulation involves fixing a layer of insulation material to the outside of your property, followed by a protective and decorative render or cladding system. It’s particularly effective for solid wall homes that lack a cavity for insulation.

This method not only enhances thermal performance but transforms your property’s exterior with finishes like modern renders or A1 fire-rated brick slip cladding.

Why Choose External Wall Insulation?

• No disruption inside – Keeps your internal décor and walls untouched.

• Improved thermal efficiency – Slash your heating costs and increase EPC rating.

• Modern exterior finish – From contemporary render to traditional brick slip.

• Moisture control – Protects walls from condensation and damp.

• Boost property value – Aesthetic and performance upgrade in one.

Government Support for Energy-Efficient Homes

UK homeowners are increasingly encouraged to improve insulation through initiatives like ECO4 and the Great British Insulation Scheme. These programmes aim to deliver warmer, more energy-efficient homes, reduce fuel poverty, and contribute to Net Zero targets.

Homeowners may qualify for grants or funding support, making this a great time to invest in external wall insulation.

Options To Insulate Your house Without Affecting Internal Walls

1. External Wall Insulation (EWI)

• Best for: Solid walls (older homes without cavity walls).

• What it is: A layer of insulation is fixed to the outside of your home, then covered with render or cladding (e.g., brick slips, wood, or tiles).

• Pros:

  • No disruption inside the house.

  • Improves appearance and weatherproofs exterior.

  • Can dramatically reduce heat loss.

• Cons:

  • Expensive (~£10,000–£15,000+ for an average home).

  • May require planning permission in some areas.

2. Cavity Wall Insulation

• Best for: Homes built after 1920s with cavity walls.

• What it is: Insulation (like mineral wool or polystyrene beads) is injected into the cavity between the outer and inner wall.

• Pros:

  • Quick and relatively cheap (~£400–£800).

  • No internal disruption.

• Cons:

  • Not suitable for walls without cavities.

  • Can cause damp problems if poorly installed in exposed or wet areas.

3. Roof and Loft Insulation

• Best for: All homes, especially those with accessible attics.

• What it is: Laying insulation material (e.g., mineral wool, rigid boards, or spray foam) in the loft floor or under the roof slope.

• Pros:

  • Highly cost-effective and DIY-friendly.

  • No interference with internal living space.

• Cons:

  • Limited effect on wall heat loss.

4. Underfloor Insulation

• Best for: Homes with suspended timber floors (not solid concrete).

• What it is: Insulating material is fitted underneath floorboards, accessible via crawl space or by lifting boards.

• Pros:

  • No wall disruption.

  • Improves comfort and reduces drafts.

• Cons:

  • Can be labour-intensive.

  • Difficult in homes without underfloor access.

Additionally: Window Upgrades

• Secondary glazing or thermal curtains can reduce heat loss without replacing entire windows or affecting walls.

Types of Render for External Wall Insulation (EWI)

Choosing the right render finish for your External Wall Insulation system is crucial—not just for appearance, but also for durability, weather resistance, and overall performance. At Vergolus, we offer a range of high-quality, UK Weber-approved render systems, each designed to suit different tastes, building styles, and environmental conditions.

Here’s a breakdown of the most popular render types used in modern EWI installations:

Silicone Render

Silicone render is currently the most popular choice among UK homeowners due to its self-cleaning properties, breathability, and resistance to algae and staining.

• ✅ Highly flexible – Resists cracking, perfect for older or movement-prone buildings

• ✅ Water-repellent – Helps prevent damp and staining

• ✅ Low maintenance – Keeps its appearance for many years

• ✅ Wide range of colours – Over 100 shades available

• ✅ Breathable – Allows trapped moisture to escape from the building fabric

At Vergolus, we frequently recommend silicone render for its blend of aesthetics and performance, especially in exposed or urban areas where pollution and weathering are a concern.

Acrylic Render

Acrylic render is a cost-effective, strong and vibrant option. It contains synthetic resins that add durability and colour retention, making it ideal for homeowners looking for bold, lasting finishes.

• ✅ Economical – More affordable than silicone

• ✅ Vibrant colour options – Excellent pigment retention

• ✅ Tough surface – Suitable for high-traffic or vulnerable areas

• ✅ Less breathable – Best suited to newer buildings or where moisture risk is low

Acrylic render is commonly used for newer builds or extensions where flexibility and breathability are less critical than colour vibrancy and cost-effectiveness.

Mineral Render

Mineral render is a dry-mix cement-based render, ideal for colder, wetter climates due to its fast-drying properties. It’s highly breathable and often used as part of traditional building renovations.

• ✅ Quick drying – Cures rapidly in cold or damp conditions

• ✅ Very breathable – Excellent for older solid-wall buildings

• ✅ Affordable – Good performance at a reasonable cost

• ❗ Needs painting – Typically requires a top coat or masonry paint for weather resistance

At Vergolus, we use mineral render in projects with tight timeframes or where breathability is paramount. It’s also ideal for heritage-style properties being upgraded with EWI.

Monocouche Render (One-Coat)

Monocouche render (French for “single layer”) is a pre-coloured, through-dyed render that creates a classic flat or scraped texture and is often used for a stone-like finish.

• ✅ Pre-coloured – No painting required

• ✅ Durable and weather-resistant

• ✅ Good for larger surfaces – Uniform appearance

• ✅ Less flexible – Not ideal for buildings with movement or settling

While less breathable than silicone or mineral renders, monocouche is often chosen for new-build homes or modern extensions where a crisp, consistent aesthetic is desired.

Custom Finishes: Brick Slips and Stone Effect

In addition to traditional renders, Vergolus also specialises in high-performance brick slip cladding—designed to mimic traditional brickwork while delivering modern insulation benefits. These A1 fire-rated finishes are ideal for:

• Conservation areas

• Heritage homes

• Customers seeking a traditional look with modern performance

Which Render is Right for You?

Each render system has unique characteristics, and the best choice will depend on:

• The age and construction of your home

• Local climate and exposure

• Desired aesthetic

• Maintenance preferences

• Budget and performance goals

Our team at Vergolus will help you select the perfect finish, ensuring both style and substance for your external wall insulation system.

Why Vergolus Is the Go-To Name in External Wall Insulation

At Vergolus, we specialise in delivering high-performance External Wall Insulation systems using St Gobain’s UK Weber—a name synonymous with innovation, durability, and safety.

• ✅ Certified by St Gobain (UK Weber)

• ✅ Installers of A1 fire-approved EWI systems

• ✅ Experts in energy-efficient building systems

• ✅ Modern render and brick slip specialists

• ✅ Fully compliant with UK building regulations

• ✅ Trusted by homeowners across the UK

As a company championing sustainable and aesthetic insulation solutions, Vergolus offers the perfect balance of performance and style. Whether you live in a period property, modern home, or for your new house extension, our tailored approach ensures the best possible result.

Benefits of A1 Fire-Approved Cladding and Brick Slip Systems

Choosing A1 fire-rated materials means complete peace of mind. Our systems exceed UK safety regulations and are ideal for:

• Urban settings

• Multi-storey properties

• Buildings close to boundaries

Brick slips combine the appearance of traditional brickwork with modern insulation technology—perfect for period homes or conservation-sensitive areas.

Ready to Transform Your Home?

Contact Vergolus today for a free consultation and discover how External Wall Insulation can future-proof your home. Whether you want to cut energy bills, boost property value, or simply modernise your exterior, our team is ready to help.

👉 Call now at 0800 433 2353 or send us a message to book your FREE thermal survey.

If you’re seeking the best way to insulate your house without affecting internal walls, External Wall Insulation is the standout solution. With modern finishes, high fire safety, and government support, there’s never been a better time to upgrade your home.

Vergolus is proud to be one of the UK’s fastest-growing, certified EWI installers—helping homeowners across the country improve thermal comfort, curb appeal, and environmental impact.