Plastic sheet may be used for secondary double glazing. Acrylic and polystyrene sheet is available from DIY superstores while polycarbonate sheet must generally be obtained from plastics specialists.

Watchpoint;-

Acrylic sheet is hydroscopic (it will absorb moisture from the atmosphere) and this may result in a slight billowing of the sheet when fixed. However, it is resistant to ultra-violet light.

Polystyrene sheet is not very resistant to degradation from ultra-violet light and generally should not be fixed to south facing windows or outdoors as it will tend to go yellow.

 Polycarbonate sheet is very tough but will still scratch- like most plastic sheets