External Wall Insulation

External wall insulation or solid wall insulation involves insulating a building by attaching a layer of insulation material to the external wall and covering it with reinforcement and finally rendering it.

Often referred to as cladding the process is great to save on heating bills but can also be protective and decorative.


What is External Wall Insulation?

There are three types of insulation that can be used for external wall insulation. These are:

  • Expanded Polystyrene
  • Mineral Wool
  • Phenolic Resin

The most popular of these is the expanded polystyrene, used as it is the most cost-effective way of carrying out the work. The others are used is more specific circumstances and you should ask your installer if you want to know more about them.

External Wall Insulation

How Does it Work?

Like cavity wall insulation, external wall insulation works by creating a barrier that prevents the heat from transferring through your walls and instead of bouncing this back in. This slows the movement of heat out through the walls, reducing your heating demand dramatically, lowering your heating bills and energy output.

The most commonly used insulation expanded polystyrene slabs contain thousands of trapped air pockets that make it an extremely good insulator. This further helps to stop the heat from escaping to the outside.

How external wall insulation works

Installation Process

Before installing our surveyor will visit the premises to ensure that external wall insulation is the right solution for your property.

Once this has been carried there are a few additional preparation bits that need to be carried out before starting. Firstly, if there is some existing render this needs to be tested to ensure it is strong enough to hold the new insulation if it is not this will need to be removed.

Secondly, all the pipework will need removing from the building, this will be reinstalled once the insulation had been attached.

Once the walls have been prepped the installers will take out the following steps.

  1. Insulating Panels fixed to the wall, with plastic capped fittings to ties panels securely to the wall.
  2. Mortar is applied to cover the insulating panels and fittings
  3. An insulating mesh is then added to the wall and sunken within the mortar applied previously
  4. The render finish (available in any colour) is applied on top of the freshly sanded and painted mortar

External wall insulation being installed

The finish available can vary. Naturally the most cost-effective is with a simple white render, but other colours are available. You can also choose s finish that is:

  • Smooth
  • Textured
  • Painted
  • Tiled
  • Panelled
  • Pebble-dashed


Before and after external wall insulation has been installed

For more information on the finishes available please speak with your installer.


Can I Benefit from External Wall Insulation?

Almost anyone can benefit from external wall insulation provided they have a solid wall. The benefits of reduced heating bills and energy expenditure are much greater than they are for other forms of insulation such as cavity wall and loft insulation, but it is also more expensive.

External wall insulation can also improve the value of the house. The EPC rating of a house has been known to jump 2 bands. This will depend on your home but it is almost certain to add value to your home as well as improving the look and feel for passersby.

In addition to the improving the comfort of your home external wall insulation can:

  • Renews the appearance of outer walls. Coloured finishes can be applied to save redecoration costs in the future
  • Improves weatherproofing and sound resistance
  • Fills cracks and gaps in the brickwork, which will reduce draughts
  • Increases the life of your walls by protecting the brickwork
  • Reduces condensation on internal walls and can help prevent damp (but will not solve rising or penetration damp)


How do I know if I Have solid walls?

Brick Patterns


If your home was built before the 1920’s the external walls are probably solid and do not have a cavity. One way to tell is to measure the width of the wall by looking at an external wall window or door. If the Brick wall is less than 260 mm then it is likely a solid wall.

Another way to tell is by looking at the pattern of the bricks. If you see a full brick followed by a half brick continuously (like the image on the right) then it is likely a solid wall. If it all full bricks this is likely a cavity wall.

The Benefits of External Wall Insulation

Will it cost me?

The average cost of external wall insulation is much greater than cavity wall insulation and will depend on the size of the property and if it detached, semi-detached, terrace, bungalow or flat.

Installation cost for external wall insulation can be between £9,000 to £26,000 and between £4,000 to £16,000 for internal wall insulation when unsubsidised.

New government criteria offers funding for those on benefits to insulate their homes however currently there is no funding for those for solid wall insulation.

We offer both finance and one time payment options.

How much will I Save?

External wall insulation saves more in energy bills and energy expenditure than any other form of insulation we offer. The cost is offset by the saving with a semi-detached medium size house saving an average of £270 per year.


The Impact on the environment

As much as 1,900kg of carbon dioxide can be saved by implementing external wall insulation for a detached house. Even for a flat, this can save as much as 600kg of carbon dioxide, making the potential benefit for the environment huge.