The Red Book

The Red Book
Test for Non-Fragility of Large Element Roofing Assemblies

ACR materials standard

ACR(M)001-2019 [Sixth edition]
“Test for Non-Fragility of Large Element Roofing Assemblies”

This publication describes a test standard which can be applied to any product which will form a roof or part of a roof and is intended to provide information about whether it can support the instantaneous loads imposed on it by a person stumbling or falling on it.

Assemblies, when tested by a competent person, may be classified as:

  • Non Fragile – Class A
  • Non Fragile – Class B
  • Non fragile – Class C

If an assembly fails this test it must be classified as “fragile ”.

The 5th edition incorporates glass rooflights for the first time by the inclusion of double skin glazing into the standard and reference to the Centre for Window and Cladding Technology (CWCT) Technical guidance notes 66,67 and 92 .

The previous 4 editions of this standard did not preclude glass, but had not accounted for the unique safety issues associated with glass. Whilst glass may pass the ACR soft body impact test set out in this document, it is particularly susceptible to hard body impacts that do not form part of the ACR test. These may cause it to shatter, and may allow shards of glass to fall onto people below.

This has been recognised by the glass industry for some time and as a result the Centre for Window and Cladding Technology (CWCT) devised specific non-fragility tests for large area glazing. These are based on the ACR soft body impact test, together with additional hard body impact tests, and limit the size of shards of glass falling from broken panes, to minimise risk to any personnel beneath.

CWCT, working in conjunction with ACR, have been able to develop a simplified test method, and also a “deemed to satisfy” solution, for these applications, where maintenance personnel will not walk intentionally on the glazing, but might accidentally step or fall onto the glazing.

Other important changes are highlighted on page 2 of the new edition and all Test Providers must ensure that they fully understand these changes. In particular there has been a more detailed determination of the height of the second drop of the sand bag impactor.

Roofs incorporating fragile assemblies constitute a “fragile surface” under Regulation 2 of the Work at Height Regulations 2005 requiring appropriate safety precautions to be taken to comply with the legal requirements of Regulation 9 (utilizing work equipment selected in accordance with the hierarchy detailed in Regulation 6) of those regulations.

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Second edition published 2000
Third edition published 24/4/2005
Fourth Edition published 7/11/2011
Fifth Edition published 31/05/2014
Sixth Edition published 31/12/2019 (amended May 2020)

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