Solid wall insulation

This will help stop heat being lost from your home and help to prevent condensation on the walls and ceilings. It's not cheap, but you will soon see the benefits to your heating bill and it's another way of playing your part in reducing carbon dioxide (CO ₂) emissions. There are two types of solid wall insulation: external and internal.

External wall insulation

Typical brick formation for solid walls.

How external wall insulation works

This involves adding a decorative weather-proof insulating treatment to the outside of your wall. The thickness of the insulation needs to be between 50 and 100mm and is usually installed where there are severe heating problems or the exterior of the building requires some form of other repair work providing the opportunity of adding insulation.

The savings

External wall insulation is more expensive than cavity wall insulation but it could save you around £500 a year on your energy bills and it could pay for itself in around 11 years.

A three bedroom semi-detached house could save around 2.5 tonnes of carbon dioxide (CO ₂) a year.

The following table gives approximate costs, savings and paybacks for external solid wall insulation however the typical cost provided does not include any financial support or grants. Financial help may be available if you're planning to make energy saving improvements to your home.

The Government, energy suppliers and local authorities all provide grants or offers to help you implement energy saving measures in your home. For more information or to search for energy saving grants and offers, please click here.

If you are going to be renovating or repairing the exterior of your walls of your house then this is a very good time to consider installing solid wall insulation. In this case, the marginal cost of external solid wall insulation (i.e. the material costs and labour when other wall repairs are being undertaken) will be lower than the full cost of installation.

Internal wall insulation

Solid walls can also be insulated by applying internal wall insulation. Types include ready made insulation/plaster board laminates or wooden battens in-filled with insulation.

How internal wall insulation works

Insulation/plaster board laminates usually consist of plasterboard backed with insulating material typically to a total thickness of up to 90mm. The construction of the laminates reduces the amount of heat which would otherwise pass through into the wall and outside.

The savings

Internal wall insulation can be cheaper than external wall insulation and you could save around £470 a year on your energy bill.

A three bedroom semi-detached house could save around 2.4 tonnes of CO ₂ a year.

The following table gives approximate costs, savings and paybacks for internal solid wall insulation:

As the interior arrangement (and therefore wall area) of homes varies considerably, it is difficult to provide a typical cost for the work. You can get an indication of how much it will cost you to install internal solid wall insulation by estimating the internal area of the walls that have contact with the outside air (you dont need to include walls that connect to other houses or walls between rooms within the house).

How it is installed

Costs for internal wall insulation start from £42 per square metre. The boards are fitted directly to the inside of the wall. The thicker the board the better the insulation. You can also attach wooden battens in-filled with insulation to a wall. This involves attaching battens to the wall, filling the spaces between the battens with insulation and then covering them with a plasterboard finish.

What to do next

If you have other questions why not visit our FAQ section. If you still have other questions why not call your local Energy Saving Trust advice centre on 0800 512 012 for free, impartial advice on saving energy in your home.

Alternatively you can find out more information on solid wall insulation from the National Insulation Association website, Insulated Render & Cladding Association.

• Find out if there are Energy Saving Recommended products available for these types of insulation
• Savings assumptions