The UK’s housing stock is estimated at approximately 24.5 million dwellings, of that approximately 36% consist of non-cavity wall construction – solid brick, solid stone, pre 1944 timber frame and non-traditional, i.e concrete construction.

Improving the thermal efficiency of solid-wall properties is an area which has massive potential for the future as this is an area where very little work has been done to date. However, more and more individuals are now starting to recognise the advantages of insulating such households and this is an area which is now seeing a real growth with many cost-effective solutions now available.

Building Detached Semi detached Mid terrace Bungalow Flat
Annual saving £455 £260 £175 £180 £145
Annual carbon dioxide saving 1,900 kg 1,100 kg 720 kg 740 kg 610 kg
Typical Installation costs * External wall insulation: £5,000 to £18,000

Internal wall insulation: £3,000 to £14,000

* Costs may vary significantly depending on level of work required.

The benefits of solid wall insulation

If you live in a home with solid walls, 45% of your heat is escaping through the walls which is costing you money. Insulating the walls will dramatically prevent heat loss in the winter

What is a solid wall?

  • 9” masonry walls and other non-traditional construction types such as single leaf masonry, >9” walls (e.g. thick stone walls)
  • Concrete walls, metal or timber panels and some mixed wall types (e.g. Where the ground and first floors are constructed of different materials)
  • BRE estimate that around 7% of unfilled cavity wall stock cannot receive CWI.
  • High rise flats (at least 6 storeys high) – esp. 1953-1972


  • Can help with condensation problem
  • Makes your home warm and cosy
  • Reduces fuel bills
  • Saves up to 45% of heat loss
  • Minimum disruption for the householder
  • Internal Wall Insulation: quick and easy to install, improves the thermal efficiency
  • External Wall Insulation: Improves appearance of the building


  • Hard to treat not really…. expensive to treat as opposed to loft and cavity wall insulation

Facts: Solid Wall Houses

  • Solid wall construction, non-traditional construction and non standard cavity are the categories that are most difficult to treat for insulation.
  • Most of these houses are privately owned, with 65% belonging to the Private Rented Sector.
  • 6.6 million properties have solid walls which represent 31% of the total housing stock.
  • 48% of the 326,000 high rise flats in England have solid walls.
  • Solid Wall properties tend to be more difficult and expensive to improve in terms of adequate insulation and heating.