Secondary glazing

If this is the case an effective alternative is secondary glazing. Secondary glazing involves fitting another window in the recess of the existing window. As well as providing thermal insulation secondary glazing can lessen noise pollution and reduce condensation. There is a range of systems available for different budgets and styles of window.

Although inexpensive products using clear acrylic sheets fitted to UPVC or plastic frames are popular, their effectiveness can be short lived (about a year). The best option employs an aluminium glazing system anchored in a hardwood sub-frame.

Some manufacturers offer installation as part of their service, but installing secondary glazing can be carried out by anyone with relatively little DIY experience.  The sub-frames are usually pre-drilled so only need fixing in the recess of the window. The tools needed to carry out the job are a spirit level, tape measure, power drill and screwdriver or cordless screwdriver. If you plan to fit the secondary glazing yourself, the main points to remember are:

• The existing or primary window should be made draught proof before fitting secondary glazing.
• For optimum noise reduction the gap between the panes should be about 100mm. But remember if the gap is much greater than 100mm, there will be room between the panes for thermal currents, which decrease the insulation value.
• Follow the manufacturer’s instructions for taking accurate measurements of your window.
• Use a spirit level to ensure the frame is perfectly vertical.

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