Low Energy House - Cavity or Solid Wall? - Solid Wall Insulation
Up to 35 per cent of all the heat lost from un-insulated homes passes through the
external walls
Cavity Wall Insulation
Cavity wall insulation is one of the most cost effective energy efficient measures
that can be taken in a home. It is estimated that, in the case of an average grant aided installation,
with the savings made on fuel bills, the insulation will pay for itself in under two years.
Cavity Wall Construction
Cavities were originally built into external walls to prevent moisture
passing from the outside of the building to the inside. The most common type of cavity wall is constructed of an inner and outer leaf of brick or block
separated by a ventilated air space or cavity.
Suitability for Cavity Wall Insulation
If the wall is considered to be suitable, insulation material can be installed in the cavity
between the inner and outer leaves. This will reduce the amount of fuel required to heat the home to
a temperature that is comfortable for the occupants.
Types of Wall Construction
Most brick houses built since the 1920s have external walls of cavity construction. It is likely,
that houses built since 1980 will have external wallswith cavities that contain some insulation.
Cavity or Solid Walls?
If the house has cavity walls then it may be possible to have them filled with insulating material.
If the house is constructed of brick, the brickwork pattern on the outside of
the house should be assessed. If the bricks have been laid with fully bonded stretchers and headers then this indicates a
solid wall. If the bricks are laid in stretcher bond then the wall is likely to have a cavity.
Wall thickness?
If the brickwork pattern is stretcher bond, the thickness of the outside wall
should be measured at a door or window position. A solid wall, including the internal plaster finish, will usually be
about 250mm (10 inches) in thickness whereas a wall with a cavity 50mm (2 inches) wide will be
approximately 300mm (12 inches) thick.
The registered installer will carry out the work using an approved insulation system and approved insulating materials. On completion of the work the installer will provide a 25 year guarantee
