Solid Wall Insulation

solid wall insulation

Insulating your solid walls may reduce your heating costs considerably. Solid walls let twice as much heat out as cavity walls do. The good news is they can be insulated.

If your home was built before 1919, its external walls are probably solid construction, rather than cavity walls. Cavity walls are made of two layers with a small gap or ‘cavity’ between them. Solid walls have no gap, so they let more heat through.

If the brickwork has been covered, you can also tell by measuring the width of the wall. If you look at the thickness of an external wall where a window or door is, if the wall is less than 260mm thick then it probably is a solid wall; a thicker wall is probably Cavity construction. Stone walls may be thicker still but are usually solid.

If you live in a house that is not made from bricks, such as a steel or timber-framed building, insulating will be different. Find out more from the National Insulation Association.

Solid walls can be insulated – either from the inside or the outside. This will cost more than insulating a standard cavity wall, but the savings on your heating bills will be bigger too.

How much you can save?

Below is a table of Solid Wall Insulation saving figures for England, Scotland and Wales.

 DetachedSemi-detachedMid-terraceBungalowFlat
Fuel bill savings (£/year)£455£260£175£180£145
Typical installation costExternal:
£5k - £18k

Internal:
£3k - £14k
External:
£5k - £18k

Internal:
£3k - £14k
External:
£5k - £18k

Internal:
£3k - £14k
External:
£5k - £18k

Internal:
£3k - £14k
External:
£5k - £18k

Internal:
£3k - £14k
Carbon dioxide savings (kgC02/year)1,900 kg1,100 kg720 kg740 kg610 kg

These are estimated figures based on insulating a gas-heated home provided by the Energy Saving Trust. Costs may vary significantly depending on level of work required.

The benefits of External Wall Insulation

  • can be applied without disruption to the household
  • does not reduce the floor area of your home
  • renews the appearance of outer walls
  • 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)
  • is best installed at the same time as external refurbishment work to reduce the cost
  • may need planning permission – check with your local council
  • requires good access to the outer walls
  • is not recommended if the outer walls are structurally unsound and cannot be repaired.

Sign up for Green Deal or ECO funding?

Apply today »

For further details on Solid Wall Insulation cost and savings…

Complete our online survey »