External Wall Insulation — Transform and Protect Your Home

Solid-wall homes lose heat twice as fast as cavity-wall properties. External wall insulation wraps your home in a thermal blanket, slashing bills and refreshing your facade.

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£640

Potential annual savings

Typical cost: £8,000 – £15,000

Solid-wall homes, typically built before 1920, account for around a third of UK housing stock and are among the least energy-efficient properties in the country. With gas prices at 6.76p/kWh and electricity at 24.67p/kWh, these homes can spend well over £2,000 a year on heating alone. External wall insulation addresses the single biggest source of heat loss — the walls — by adding a layer of rigid insulation board and a protective render finish to the outside of the building, cutting heat loss by up to 45%.

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Potential annual saving

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Typical installation cost

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Average payback period

Wall heat loss prevented

What Is External Wall?

External wall insulation (EWI) involves fixing a layer of insulation material — typically expanded polystyrene (EPS) or mineral wool boards — to the outside of your external walls. This is then covered with a reinforcing mesh and finished with render, brick slips, or cladding. The system creates a continuous thermal envelope around the building, eliminating cold bridges and dramatically reducing heat loss.

How It Works

Survey and Design

A detailed survey assesses your walls, identifies any structural issues, and determines the optimal insulation thickness and finish for your property.

Scaffolding and Preparation

Scaffolding is erected around the property. Existing fixtures such as downpipes, satellite dishes, and window sills are removed or extended.

Insulation and Render

Insulation boards are mechanically fixed and adhesive-bonded to the walls. A reinforcing mesh is embedded in a base coat, followed by the chosen decorative finish.

Completion

Fixtures are refitted, scaffolding removed, and a final inspection confirms the installation meets PAS 2030 quality standards.

Is It Right for My Home?

External wall insulation is primarily designed for solid-wall properties, which includes most homes built before 1920. It can also be applied to non-traditional construction types such as concrete panel or steel-framed homes. The property must have sufficient ground clearance, and planning permission may be required in conservation areas or for listed buildings. A structural survey is needed to confirm the walls can support the additional weight.

Key Benefits

Major Bill Savings

Save up to £640 per year by dramatically reducing heat loss through solid walls, which account for the largest share of energy waste in older homes.

Weatherproofing

The render finish protects your walls from rain, wind, and frost, reducing maintenance costs and extending the life of the underlying brickwork.

Fresh New Look

Choose from a wide range of render colours and textures to completely transform the appearance of your home.

Eliminate Cold Walls

Internal wall surfaces become warmer to the touch, eliminating cold spots and reducing the risk of condensation and mould.

No Internal Disruption

All work is carried out from outside, so you can continue living in your home normally throughout the installation process.

Increase Property Value

A higher EPC rating and improved kerb appeal can add significant value to your property, often more than the cost of the installation.

Cost Breakdown

Our partner network means you'll typically pay less than these averages.

Property Type	Typical Cost	Annual Saving	Payback
Detached	£12,000 – £15,000	£640	18–23 years
Semi-Detached	£8,000 – £12,000	£440	18–27 years
Terraced	£8,000 – £10,000	£330	24–30 years
Bungalow	£8,000 – £11,000	£380	21–29 years

Government Grants Available

ECO4

ECO4 can fully fund external wall insulation for eligible low-income households. This is one of the highest-value measures available under the scheme.

Check Eligibility →

Warm Homes Plan

The Warm Homes Plan provides grants towards external wall insulation for fuel-poor households, significantly reducing the upfront cost.