Cavity Wall Insulation
About a third of all the heat lost in an uninsulated home escapes through the walls. By properly insulating cavity walls, you will save energy and cut costs off your heating bill.
In general, houses built from the 1990s onwards have wall insulation to keep the heat in, but if your house is older than that, it may not have any wall insulation at all.
Houses in the UK mostly have either solid walls or cavity walls:
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If your house was built after the 1920s, it is likely to have cavity walls. A cavity wall is made up of two walls with a gap in between, known as the cavity; the outer leaf is usually made of brick, and the inner layer of brick or concrete block.
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Pre-1920 older houses are more likely to have solid walls. A solid wall has no cavity; each wall is a single solid wall, usually made of brick or stone.