Security performance of glass

Having taken all security measures with the frames of your windows and doors it is important to consider the glass. There would be little point in having a secure window if a burglar could simply break through the glass and gain entry to the building.

Types of glass

Unprocessed glass or float glass will break easily resulting in large shards of glass. This therefore has no security value. Toughened glass is stronger, but can be broken relatively easily and quietly using a center punch, so this also has no security value. Laminated glass is more difficult to get through as the interlayers in the glass hold it together once broken. However, the security performance of different laminated glasses will vary, so it should be confirmed by testing.

Security testing for glass

The burglary resistance of glass is determined by testing to BS EN 356. This standard has a range of classifications from P1A to P8A and requires the glass to be tested by dropping a 4.11 kg 100mm steel ball onto the glass from heights ranging from 5m to 9m, with an axe attack for the higher classifications (P5A upwards).

Glass identification

Unless float glass is supplied, the manufacturer should etch the relevant standard onto the corner of the glass so that it can be visible when fitted to the window or door. These markings can then be used to identify the type of safety glass fitted. The standards that you should expect to see are as follows:

  • Toughened or heat soaked toughened: BS EN 12150 or BS EN 14179
  • Laminated: BS EN 14449
  • Burglar resistant: BS EN 356 followed by the class (e.g. P1A)

What type of glass is required for compliance with Approved Document Q?

The glass requirement is not directly stated in AD Q. However, AD Q refers to PAS 24, which in turn refers to the SBD New Homes document. The SBD New Homes document requires any non-lockable accessible windows and all doors to be fitted with P1A glass.