The majority of houses built after 1930 have cavity walls. It is very rare for houses build before 1920 to have cavity walls, while most houses built after 1985 will have been constructed with cavity insulation built in.

The simplest way to tell if your house has cavity or solid walls is usually by looking at the pattern of the brickwork.   

In a cavity wall, all of the bricks are 'stretchers' i.e. all long-ways on, as in the photograph to the right.   

If your house has cavity walls, click here to find a cavity wall insulation installer in your local area.

Walls without a cavity have a mixture of stretcher and 'header bricks' i.e. end-ways on, as shown in the photographs below. The headers can usually be seen in continuous rows, with a number of stretcher rows between them.

If the walls of your house are rendered, the thickness of the wall can be used as an indication of their construction. It is usually easiest to measure this at a window or doorway. A cavity wall is around 30cm wide (two 4.5 inch bricks and a 2.5 inch cavity) while a solid wall is around 23cm wide (a 9 inch header brick without a cavity).

As solid walls cannot be insulated with cavity wall insulation material, an alternative method of increasing the wall temperature is to apply a polystyrene wall veneer. Rolls of material such as Warmaline are available from DIY and wall paper stockists. This is particularly effective at reducing condensation on the wall.

Higher insulation values can be obtained through the construction of studwork inside the walls which can then be filled with sustainable insulation materials such as recycled newspaper or natural sheep wool insulation. This also an option in individual flats where the whole cavity wall cannot be filled. Click here to find specialist companies. 

If your house has got cavity walls, click here to find a cavity wall insulation installer in your local area.