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Approved Document N - FAQ

When was Part N introduced?

Part N was introduced on 1 June 1992. Before that date glazing was not controlled under the Building Regulations. However, there was a British Standard, BS 6262: 1982, Glazing for Buildings, which set out good practice.

Approved Document N refers to the impact classes determined by the method described in BS 6206: 1981. Can the classes described in BS EN 12600:2002 be used instead?

When a British Standard referred to in an Approved Document is revised or updated the new version may be used provided it continues to address the relevant requirements of the Regulations. However, BS EN 12600 is a replacement, rather than an update of BS 6206 and it will be necessary to issue an amendment to Approved Document N to change the guidance. Until this is done, it is open to Building control bodies to accept flat glass products that have been tested to the appropriate class of BS EN 12600 if they consider the products satisfy Requirement N1 in any particular case.

How do the impact classes defined in BS 6206: 1981 relate to those defined in BS EN 12600:2002

The full rating determined by BS EN 12600:2002 covers more aspects of impact performance than the BS 6206 rating. For the drop height test (α in BS EN 12600) research1 has shown that for practical purposes the equivalence is:

BS 6206

BS EN 12600

Class A

Class 1

Class B

Class 2

Class C

Class 3

1 Building Research Establishment; IP 1/05, Impact test standards for glass: comparison of BS 6206 and BS EN 12600. ISBN 1 86081 736 X. Available from BRE Bookshop, website: www.brebookshop.com


Approved Document M (2004) also gives guidance on manifestation design. Where there appears to be a conflict between the guidance in Approved Document N and Approved Document M which takes precedence?


The guidance in Approved Document M deals with ensuring ease of access to and around buildings which is different from the minimum standards necessary to secure the safety of people moving around the building. Where wheelchair users are likely to be using the building, the guidance in Approved Document M is more appropriate.