Transform Your Home’s Exterior and Cut Energy Bills with EWI Pro

Find out how external wall insulation from EWI Pro can boost your home’s kerb appeal and energy efficiency.

What is External Wall Insulation?

External Wall Insulation (EWI) is a method of improving your home’s thermal performance by attaching a layer of insulation to the outside of the existing walls. This layer reduces heat loss through the walls, helping to maintain a comfortable indoor temperature all year round.

At EWI Pro, we supply a range of insulation options, including Expanded Polystyrene (EPS), Mineral Wool, Phenolic Foam and Wood Fibre, each suited to different property types and performance needs. Once the insulation is installed, it is finished with a protective, weather-resistant layer such as silicone render, lime render or brick slips, which also enhances the appearance of the property.
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Benefits of External Wall Insulation

Enhanced Energy Efficiency
By reducing heat loss through the external walls, EWI helps to lower your home’s overall energy consumption and heating costs.
Improved Kerb Appeal
With a wide choice of finishes, colours and textures, EWI can completely transform the look of your home, giving it a fresh, modern appearance.
Increased Property Value
Upgrading your home’s energy performance and exterior appearance can boost its market appeal and long-term value.
Greater Indoor Comfort
EWI creates a more consistent internal temperature, eliminating cold spots and making your home warmer in winter and cooler in summer.
Low Maintenance & Long Lifespan
Durable and weather-resistant, EWI systems are designed to last for decades with minimal upkeep required.
Protects the Building Structure
By shielding walls from rain, frost, and temperature swings, EWI extends the life of your home and prevents common issues like damp and cracking.
Better Acoustic Insulation
Certain insulation types, such as Mineral Wool, also reduce noise from outside, which is ideal for homes near roads, railways, or busy areas.
Reduced Carbon Footprint
Lower energy usage means fewer carbon emissions, helping your household reduce its environmental impact.

How Much Can You Save with External Wall Insulation?

Heating makes up over half of a typical UK energy bill, around £700–£760 per year. By installing External Wall Insulation (EWI), homeowners can dramatically reduce heat loss, cut energy bills and improve home comfort all year round.

We’ve broken down typical costs, annual savings and estimated payback times for the most common UK homes where EWI is installed:
Detached
Detached homes lose more heat due to multiple exposed walls. EWI can make a big impact on both energy bills and indoor comfort.

Typical EWI Cost: £15,000 – £20,000
Estimated Annual Savings: £1,200 – £1,500
Payback Time: Approx. 12-15 years

Figures are based on current Ofgem energy price caps and average UK inflation as of 2025.
Semi-Detached
Semi-detached homes benefit hugely from EWI, especially where heat escapes through the gable wall.

Typical EWI Cost: £12,000 – £16,000
Estimated Annual Savings: £1,000 – £1,300
Payback Time: Approx. 11-13 years

Figures are based on current Ofgem energy price caps and average UK inflation as of 2025.
Mid-Terrace
Mid-terrace homes lose less heat overall, so installation costs are lower – making payback times faster.

Typical EWI Cost: £1,000 – £15,000
Estimated Annual Savings: £800 – £1,000
Payback Time: Approx. 12-13 years

Figures are based on current Ofgem energy price caps and average UK inflation as of 2025.
Bungalow
Bungalows tend to lose heat quickly through walls and ceilings – EWI helps keep warmth in where it matters most.

Typical EWI Cost: £12,000 – £16,000
Estimated Annual Savings: £1,100 – £1,400
Payback Time: Approx. 11-13 years

Figures are based on current Ofgem energy price caps and average UK inflation as of 2025.

All costs, savings and payback times are estimates and can vary depending on your home’s size, energy use and insulation thickness – but comfort and kerb appeal improvements are immediate!

Is My Home Suitable for External Wall Insulation?

Before going ahead with External Wall Insulation (EWI), it’s important to check if your property is suitable and whether planning permission or building regulations apply.
Which homes are suitable?
EWI is ideal for:
Solid wall properties – typically built before the 1920s, with no cavity to fill.
Non-traditional constructions – such as concrete or steel-framed homes (e.g. Airey or No-Fines).
Poorly insulated homes – especially where cavity wall insulation isn’t possible or has failed.
However, some homes need extra consideration:
Homes in conservation areas or listed buildings – changes to the external appearance will almost always require planning permission.
Terraced or semi-detached homes – insulation may cause a visible ‘step’ between neighbouring properties, so consent or agreement may be needed.
Homes with boundary restrictions – EWI adds thickness to the walls (usually 90–110mm), so it’s important to check if this will encroach on pathways or neighbouring land.
Do you need planning permission?
In most cases, EWI falls under permitted development, so you won’t need planning permission. But you will need it if:
You live in a listed building or conservation area
The insulation will drastically change the property’s appearance
Your local council has removed permitted development rights (Article 4 Direction)
Do building regulations apply?
Yes, your installer must comply with building regulations to ensure your home remains safe, warm and structurally sound. This includes:
Meeting thermal performance standards (U-values)
Ensuring proper fire safety, moisture resistance and ventilation
Using certified systems installed by trained professionals

What is an EWI system made up of?

An External Wall Insulation (EWI) system is built up in multiple layers, each playing a vital role in performance and protection – hover over the markers below to view the different stages of an EWI system.
Decorative Finish
Topcoat Primer
Fibreglass Mesh
Basecoat
EPS Insulation
Mechanical Fixings
Starter Track & Clip-on Profile
Adhesive
Substrate Preparation

Our Most Popular Choice for HomeownersExpanded Polystyrene (EPS) Insulation System onto Brick

This trusted system uses EPS insulation applied to brick walls. It’s affordable, easy to install and ideal for many property types. The system uses EPS adhesive and plastic fixings to reduce heat loss and improve durability.

Various decorative finishes are available to finish the system and enhance kerb appeal. When installed on a solid brick wall, 90mm of EPS can achieve a U-value of 0.30 W/m²K — meeting modern energy efficiency standards.

This system helps lower energy bills, improves indoor comfort and gives your home a clean, modern look.

What Insulation Types Can You Choose From?

EPS
Lightweight and cost-effective, EPS is perfect for standard properties with solid brick/block walls. It’s easy to install and offers excellent thermal performance for most domestic applications.
Mineral Wool
A breathable, non-combustible option ideal for properties that require fire resistance or vapour permeability, such as older buildings or those in multi-occupancy settings.
Phenolic Foam / PIR
High-performance insulation boards, best for areas with space constraints. They offer excellent thermal efficiency in a thinner profile, making it suitable for modern builds or retrofit projects.
Wood Fibre
An eco-friendly choice, Wood Fibre insulation is ideal for heritage properties or homes looking to use natural materials. It provides excellent breathability and moisture regulation.

Curious about what goes into an EWI system?

Order a sample box to explore our insulation options first-hand.

What Finish Options Are Available?

Explore our range of decorative finishes to complete your EWI system, from modern silicone renders to traditional lime and realistic brickslips.

MOST POPULAR CHOICE

SILICONE RENDER

  • Highly flexible & resistant to cracking
  • Water-repellent yet breathable
  • Low maintenance, dirt-resistant surface
  • Available in a wide range of colours
  • Ideal for modern homes & renovations

TRADITIONAL LIME

  • Breathable & moisture-regulating
  • Eco-friendly & traditional cement-free composition
  • Naturally flexible – reduces cracking risk
  • Helps preserve older buildings
  • Ideal for heritage & solid wall properties

OTHER RENDERS

  • Includes Mineral & Acrylic render
  • Mineral render is ideal for cold weather application
  • Mineral render is sealed with silicone paint
  • Acrylic render offers a vibrant, impact-resistant finish
  • Best suited for dry conditions & smooth results

BRICKSLIPS

  • Mimic the look of real brickwork
  • Durable & weather-resistant composition
  • Easy to install over External Wall Insulation systems
  • Available in various colours and textures
  • Great for properties in conservation areas
Once you’ve chosen your finish type, you can select from a wide range of colours & textures to suit your style.

Whether you want a subtle, traditional tone or a bold, modern look, there’s something to suit every property.
Silicone & Acrylic Renders can be tinted in thousands of colours, including RAL, NCS and Pantone shades.
Mineral Render is sealed with a breathable silicone paint, giving you even more colour flexibility.
Lime Basecoat and Lime Paint offer a breathable, traditional finish and can be tinted with natural pigments.

Timeline: How External Wall Insulation Is Installed

Day 1-2: Final Checks & Substrate Prep
Property survey – Final measurements, checks for suitability and discussion of finish options.
Access setup – Scaffolding is erected and protective sheeting is installed.
Surface prep – Existing render may be removed and walls are cleaned or primed.
Day 3-5: Insulation Boards Applied
Insulation boards are fixed to the external walls using adhesive and mechanical fixings.
Beads and trims are installed to reinforce corners, edges and openings.
Day 6-7: Basecoat & Mesh Reinforcement
A basecoat layer is applied over the insulation boards.
Fibreglass mesh is embedded into the basecoat for strength and crack resistance.
Once dry, a second pass may be applied to smooth the surface.
Day 8-9: Priming & Decorative Finish
Topcoat primer is applied to help the final render bond properly.
The chosen decorative finish (e.g. silicone, acrylic, mineral, or lime render) is applied.
This stage adds colour, texture and weather protection.
Day 10-14: Curing & Finishing Touches
The system is left to fully cure.
Final details are completed, such as downpipe refits, sealant around windows and any painting or cleaning up.
Scaffolding is removed and your new façade is revealed!

Need More Information About EWI Pro Products & Systems?

Explore everything you need to know about external wall insulation in one place.

Our complete guide covers:
The different types of insulation and which is right for your home
A breakdown of EWI system components
Popular render finishes and colour options
How EWI is installed and maintained
Whether you’re just starting your journey or ready to make a decision, this guide is the perfect place to begin.
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Ready to Transform Your Home? Let’s Get Started

Whether you’re ready to kickstart your renovation or simply want to learn more, we’re here to help you explore how EWI can transform your home.

Fill in a few quick details below, and our team will be in touch to guide you through your options, from insulation types and finishes to approved installers and project timelines.
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