Specialist Internal Wall Insulation Installers

Internal Wall Insulation (IWI) is an extremely effective means of insulating solid wall properties to significantly reduce the amount of heat lost through the walls.

The installation process involves fixing a layer of insulation material to the internal walls of a property, finished with plasterboard to leave a smooth and clean surface for redecoration.  Decoration and the movement of fixtures and fittings are generally included within the installation package.

Cornerstone specialises in the insulation of solid wall properties and has internally insulated countless domestic properties all over the UK, including private and social housing, as an alternative solution to External Wall Insulation (EWI).



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 internally or externally, with the cost depending on the property size and condition. Internal Wall Insulation (IWI) offers a number of benefits:

Creates a warmer and more comfortable home

Significantly lowers your energy bills

Improves the appearance of your property

Can be carried out on a room-by-room basis

Prevents condensation and mould growth

Increases the value of your property


Enquire about Internal Wall Insulation today...


If your home was built 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.

Internal wall insulation is applied to the internal face of a property’s external walls 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.

IWI is suitable for all properties but is most often installed in homes where External Wall Insulation (IWI) is not appropriate, such as listed buildings or those located in a conservation area.  While IWI may impact internal living space and be more disruptive throughout installation, it is often cheaper, quicker and less complex to install than EWI and won’t require planning permission.


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


The cost of IWI varies between properties, from around £4,000 to £12,000 depending the on the size and condition of a property. 


Approximate Annual Energy Bill Savings*
Save around £425

*Figures from the Energy Saving Trust, based on insulating a gas-heated home

Approximate Annual Energy Bill Savings*
Save around £255

*Figures from the Energy Saving Trust, based on insulating a gas-heated home

Approximate Annual Energy Bill Savings*
Save around £160

*Figures from the Energy Saving Trust, based on insulating a gas-heated home

Approximate Annual Energy Bill Savings*
Save around £175

*Figures from the Energy Saving Trust, based on insulating a gas-heated home


“The project at Orchard Park demonstrates that park homes can be insulated effectively. Park home residents are some of the most vulnerable residents in our Borough, living in homes with little or no insulation to keep them warm during the colder months. The funding CWAC was successful in obtaining from NEA will help the residents of Orchard Park benefit from reduced fuel bills and improved wellbeing.”

Emma Edwards, Low Carbon Projects Officer at Cheshire West and Chester Council

“EDF Energy has contracted with Cornerstone to deliver installation services to offer insulation and heating measures under our ECO2 obligation programme. From the outset they have shown a thorough understanding of the customer journey requirements and have received a number of positive compliments as a result; we have been satisfied that they are a customer focused organisation who go the extra mile to deliver the quality of services we require and are happy to provide an endorsement of their services we have received to date."

Steve Lawrence, ECO Obligation Key Partnerships Manager, EDF Energy

“The end to end experience with Cornerstone was first class. They have excellent technical knowledge and designed a system that perfectly meets our needs. The installation process was quick and clean and we were kept informed every step of the way. More than a year into operation and the system has reduced our heating costs by around 35%, with Cornerstone continuing to provide support throughout. I would thoroughly recommend Cornerstone."

Kim Hazell, Director, Chichester Close Saltdean RTM Company Ltd, Sussex

Cornerstone is based in East Anglia and can generally provide services from individual installation level upwards in the following locations:

Norfolk,  Suffolk, Essex, Cambridgeshire, Peterborough, Bedfordshire, Lincolnshire, London, Kent, Sussex, Buckinghamshire, Berkshire, Nottinghamshire

However, we can deliver larger projects across the length and breadth of mainland England, from the South West to the North East.

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.