Solid Wall Insulation

Solid 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.

protect your home from heat loss

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 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 internally or externally.

Internal Wall Insulation

This is the cheaper of the two options, but also the most disruptive. Internal fixings such as radiators, electric sockets and skirting boards would need to be removed for the insulation to be installed and it will reduce the size of your room. To insulate effectively you will need around 100mm thickness of insulation (about 4 inches) on all the outside walls. Once the insulation has been installed, you would also need to redecorate. The average cost of internal wall insulation, based on a 3 bed semi-detached house is £5,500 to £8,500.

External wall insulation

This involves fixing an insulating layer to the outside of the house, and putting a render or cladding over the top. Render is generally the cheaper option. Cladding comes in a variety of forms including brick, tiles, timber or shingles. This 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.

Stone walls

A typical stone wall will be constructed of two skins of stone with the gap between filled with rubble. Thinking used to be that the rubble fill was just a cheap form of construction, but the reality is that it is designed to work in a particular way. Rainwater will penetrate the outer skin and some of that water will find its way to the rubble-fill. Because the rubble is relatively loose the water drops through it to the ground and away, preventing the inner skin becoming damp. 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.

Brick walls

Rainwater will penetrate less far into brick than 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 insulation.

Benefits of External Wall Insulation:

  • Helps reduce heat loss
  • Save up to £475 a year on your energy bills.
  • Save around 1.9t of CO2 every year.
  • Reduce condensation problems in the property
  • Gives your property a  facelift


Before, During External Wall Insulationand After


Grant funding

There is funding available to help towards the cost of Solid Wall Insulation. This funding is allocated on a first-come, first-served basis. Please complete the form in the green box to the right or alternatively you can contact the Energy Saving Grants Team on 0330 223 0333

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