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Safety Glass

• Introduction
• Published guidance
• Glass selection

Introduction

• The concept of "safety glass" has been around for decades but the situation has become more complicated since the publication of BS EN 12600 in 2002. Some glass manufacturers are still quoting test results to BS 6206, some have moved-on to BS EN 12600, some are quoting both. The Building Regulations Approved Document N still refers to BS 6206.
• This page seeks to provide some basic guidance for the simplest specifications for safety glass.

Published guidance

Legislation - England and Wales

Remember that following the Approved Documents is the easiest way to comply with the Building Regulations, but it is not the only way - see Use of Guidance.

• Approved Document N : The key legislative document referring to the safety aspects of glazing is Approved Document N. This, in turn, invokes British Standard BS 6206.
• Clause 1.1 - Critical locations (Page 6) : Shows where safety glass is required by reference to Diagram 1 (same page).
• Clause 1.3 - Safe breakage (Page 6) : States which Class of safety glass (to BS 6206) is required in each location in Diagram 1.

British Standards

Remember that compliance with British Standards is not mandatory unless invoked by legislation. In this case one of the standards listed below (BS 6206) is invoked by Approved Document N (see above) whereas the other (BS EN 12600) is not, yet.

• BS 6206:1981 : Impact performance requirements for flat safety glass and safety plastics for use in buildings : This standard sets out the criteria for "safety glass" in three categories - Classes A, B, and C (where A is the "best"). It does not specify the situations where "safety glass" is required, nor which Classes are appropriate in which situation. This is covered, primarily, in Approved Document N.
• BS EN 12600:2002 : Glass in building - Pendulum test - Impact test method and classification for flat glass : This standard effectively replaces BS 6206 although the two standards are not directly comparable.
• BS EN 12600 uses a three-part classification system in the format N1(L)N2 where:
  N1 : Either 1, or 2, or 3. The strength of the glass, measured by the maximum drop height at which the glass does not break. 1 is approximately comparable to Class A of BS 6206, 2 is approximately comparable to Class B of BS 6206, and 3 is approximately comparable to Class C of BS 6206.
  L : Either A, or B, or C. These describe the mode of breakage on the following basis: Type A mode of breakage typical of annealed glass; Type B mode of breakage typical of laminated glass; Type C mode of breakage typical of toughened glass. It should be noted that A is not necessarily better than B, nor B better than C, they are just different.
  N2 : Either 1, or 2, or 3. This refers to the containment aspects of the glass when broken. There is a detailed explanation in BRE IP 1/05 (see below) but, in principle, 1 is better than 2 and 2 is better than 3.
• It should be noted that both the mode of breakage and the containment are "new" concepts in BS EN 12600 and are not yet referred to in UK legislation, although they may be in the future.
• BSi have announced their intention to use BS EN 12600 as the primary standard for the Kitemark scheme for safety glass - see [www.bsi-global.com].

BRE Publications

• BRE Information Paper IP 1/05 : Impact test standards for glass: Comparison of BS 6206 and BS EN 12600 : This is by far the best reading for those who wish to study the subject in detail. It is available from [www.brebookshop.com] - put "impact standards" in the Search box; it is also available, for subscribers, on the NBS/IHS Construction Information Service.

Glass selection

BS 6206 Class A

• BS EN 12600 : 1** (approximate equivalence).
• Toughened glass : Toughened Glass, of at least 4mm thickness, should meet the classification 1C*. Pilkington state that all their toughened glass is classified 1(C)1. Saint-Gobain refer to their products being tested to BS EN 12600 test but do not state the resulting classification. The BRE tests referred to in IP 1/05 classified normal (non-patterned) 4mm toughened glass as 1(C)2, and normal (non-patterned) 6mm toughened glass as 1(C)1.
• Laminated glass : Laminated Glass with a 0.76mm PVB interlayer is classified 1(B)1. This is referred to by both Pilkington and Saint-Gobain in their trade literature and confirmed by the results of the BRE tests referred to in IP 1/05.
• Glass choice : 4mm toughened glass or 6.8mm laminated glass are the "base specifications" for Class A compliance.

BS 6206 Class B

• BS EN 12600 : 2** (approximate equivalence).
• Toughened glass : All Toughened Glass complies.
• Laminated glass : Laminated Glass with a 0.38mm PVB interlayer should be classified 2(B)2. This is referred to by both Pilkington and Saint-Gobain in their trade literature, and confirmed by the results of the BRE tests referred to in IP 1/05.
• Glass choice : 4mm toughened glass or 6.4mm laminated glass are the "base specifications" for Class B compliance.

BS 6206 Class C

• BS EN 12600 : 3** (approximate equivalence).
• Toughened glass : All Toughened Glass complies.
• Laminated glass : All Laminated Glass complies.
• Glass choice : 4mm toughened glass, 6.4mm laminated glass, (or wired glass), are the "base specifications" for Class C compliance.

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