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External Wall Insulation (EWI)

External Wall Insulation can save up to 45% on your heating bills

external wall insulation

External Wall Insulation

Uninsulated solid walls lose heat at a rate of around 45%, meaning that for every £100 spent on heating an uninsulated solid wall property, around £45 is being wasted and escaping into the outside environment.

The good news is solid walls can be insulated and it is one of the most effective home improvements that can be made, with typical savings on gas heating bills of £445 – £475 per year! If you use oil, electricity or LPG as your heating source then these savings can be considerably higher!

Most properties built before 1920 were constructed with solid walls – this accounts for around a third of homes in the UK. There are two ways of insulating a Solid Wall – either externally or internally.

Check Your Eligibility Using Our Grant Checker

Please ensure that all information provided below is 100% accurate. Any errors in your personal information could delay or prevent you qualifying for a government funded grant.

Please note that you do not necessarily need to be in receipt of tax credits or benefits as we still may be able to obtain funding for you via your Council or through other funding schemes.


This involves fixing an insulating layer to the outside of the house, and rendering or cladding over the top. Render is generally the cheaper and most popular option. Cladding comes in a variety of forms including brick, tiles, timber or pebbledash. External Insulation is the preferred method of insulating a solid wall for most people and the good news is that there is funding available for External Wall Insulation. 

There are two basic kinds of solid wall: brick, which is typically 225mm thick, and stone which tends to be a lot thicker, and works in a different way.



A typical stone wall will be constructed of two skins of stone with the gap between filled with rubble. Render or cladding on the exterior of a stone wall can act as a waterproofer and will reduce the amount of moisture penetrating the wall.



Rainwater will not penetrate as far into brick as it will into stone. The critical issue is the dew-point. When warm air meets cold air it condenses and moisture is released. In an uninsulated brick wall that point will be towards the outer surface of the wall. Insulating internally tends to draw the dew-point into the wall. What needs to be avoided is drawing it in to the inner surface of the wall – the best method of preventing this from occurring is to fit External wall insulation.


External wall insulation is a highly advanced insulation treatment
which is applied to a properties’ external walls. The system comprises of a layer of insulation, a layer of insulating render implanted with reinforcing mesh, followed by a final coat of attractive decorative render finished to your desired effect, maximising the ‘curb appeal’ of your property.

External Wall Insulation FAQ


  • External Wall Insulation can save you approximately £490* per year on your bills

  • Can enhance the appearance of your home

  • Can reduce condensation and penetrating damp problems in your home

  • Will increase your property’s value by significantly improving its ‘kerb appeal’ and energy efficiency (EPC) rating

  • Provides a high level of thermal efficiency, making your home warm and cosy

  • A variety of finishes available, including coloured render and pebbledash

* Estimated figures based on insulating a gas-heated, semi-detached home with 3 bedrooms.

ewi grants

Figure 1
Photo taken using a thermal-imaging camera, showing heat loss through loft and walls of house (yellow and red indicate greatest areas of heat loss)

ewi funding

Figure 2
Photo taken after external wall insulation and loft insulation had

what does ewi look like
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