The External Wall Insulation & Solid Wall Insulation Specialists Installers, offering Funding & Grants in Sussex

External Wall Insulation (EWI) is an extremely effective means of insulating solid wall properties to significantly reduce the amount of heat lost through the walls. Cornerstone operates throughout Brighton & Sussex.

The installation process involves fixing a layer of insulation material to the external walls of a property, and covering it with reinforcement and a special render in a range of decorative finishes. Cornerstone was originally established as an EWI specialist in 2004 and has externally insulated thousands of domestic properties all over the UK, both for private owner occupiers and landlords, as well as on behalf of local authorities and housing associations.



Uninsulated solid walls can leak up to 45% of a property’s heat – insulating these walls can save up to £425 per year on your energy bills.* Solid walls can be insulated externally or internally, with the cost depending on the property size and type. External Wall Insulation (EWI) offers a number of benefits:

Creates a warmer and more comfortable home

Significantly lowers your energy bills

Improves the appearance of your property

Reduces external property maintenance

Prevents condensation and mould growth

Increases the value of your property

Increases sound-proofing of your property

A 25 year insurance backed guarantee

EWI Before
EWI During
EWI BAfter

Enquire about External Wall Insulation today...


If your home was built in Sussex before 1920, it will most likely have solid external walls with no cavity. The lack of a cavity means more heat can escape from your house through the walls.

External wall insulation is applied to the external face of the wall and can often be the single biggest home improvement you can make to reduce heat loss.  The insulation makes it much more difficult for the heat to pass through your walls, keeping as much of it as possible inside your home for as long as possible.

You should be able to tell which wall type you have by looking at the brickwork on the outside of your house. If your home has solid walls, you will be able to see a pattern showing the long and short side of the bricks like Fig A.

If your home has cavity walls, you will only be able to see the long side of the bricks like Fig B.

It is suitable for the majority of properties, including those of non-traditional construction, but not for listed buildings or those located in a conservation area.  If that is the case for your home, you may be able to consider internal wall insulation as an alternative.  Generally, planning permission will not be required if the finish will be similar to the existing property exterior, although your local planning department will be able to confirm this.


Cornerstone has installed more than 350,000m² of External Wall Insulation to date


Approximate Annual Energy Bill Savings**
Save around £425

Approximate Cost*
£12,000 - £14,000

*Cornerstone estimate based on standard property sizes 
**Figures from the Energy Saving Trust, based on insulating a gas-heated home


Approximate Annual Energy Bill Savings**
Save around £160

Approximate Cost*
£5,000 - £7,500

*Cornerstone estimate based on standard property sizes 
**Figures from the Energy Saving Trust, based on insulating a gas-heated home


Depending on your households circumstances, funding could be available to contribute towards the cost of EWI.  Finance options are also available.


01379 853 613

Registered Office: Cornerstone (East Anglia) Limited, Unit 2-4, Fuller Road, Harleston, Norfolk, IP20 9EA.
Registered No.05117129. Registered in England and Wales.