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To reduce the risk of falls through roofs the Advisory Committee of Roofsaftey (ACR) along with the Health & Safety Executive commissioned and published material standard ACR[M]001:2000 ‘Test for Fragility of Roofing Assemblies’.

It was agreed that Non-Fragility cannot be claimed of a single component in isolation. It is only the installed system combination, including the profiles, rooflights, fasteners and sealants, that can be described as Non-Fragile and only when successfully tested as an 'assembly'. 

Non-fragility Test Criteria: 45kg bag dropped from 1200mm height onto test sample

Fragile: The bag drops through or creates a hole large enough for a person to fall through

Class C (Non-fragile): The bag is retained for five minutes minimum

Class B (Non-Fragile): Bag is retained for a further five minutes following a second drop on the same area

Class A (Non-Fragile): No significant damage to the test sample (Concrete roofs only)

The fourth edition of the ACR document has recently been issued; ACR[M]001: 2011 ‘Test for Non-Fragility of Profiled Sheeted and Large Element Roofing Assemblies’. 

All CA Building Products' roof systems, when fully and finally fixed, achieve Class B classification.  The Non-Fragility tests have been undertaken to the following criteria;

  • ≤1800mm purlin centres
  • 1.5mm (minimum) thick purlins
  • ≤70° hip angles
  • ≥45m self-curved roofs
  • ≤45m crimp-curved roofs
  • Therma-light rooflights installed over metal on both side laps
  • Single, double and multi-spanning metal liners and top sheets
  • Double and multi-spanning liner and external rooflights only, (i.e. no single spanning rooflights)
  • All edge distances, (liner, GRP Therma-light liner, top sheet & GRP Therma-light top sheet) fixing patterns and sealants as stated in the installation guide


  • Non-Fragile – In the event of a fall you will not go through the roof - May not be walkable
  • Walkable – In the event of a fall you could go through the roof - May be walkable but not advised
  • Non-Fragile and Walkable – It is safe to walk across the roof without damage or fear of falling through

For further help and advice please see the following Technical Information papers (TIPs)

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