Low Energy House

Low Energy House - Cavity or Solid Wall? - 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

Solid Brick Wall with Stretchers and HeadersIf 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 walls with cavities that contain some insulation.

Cavity Wall with Brick StretchersCavity 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