Non-Fragility

The Red Book “ACR[M]001:2005” defines a test for non-fragility which can be applied to any roof assembly, intended to indicate whether the roof can support the instantaneous loads imposed on it by a person falling or stumbling on it. It is not a product test but products such as rooflights can be tested as part of a roof assembly.

The test defines 3 Classes of non-fragility (A, B or C). Most roof constructions (without rooflights) are Class B or C; very few achieve Class A. Generally a rooflight should match the performance of the roof (eg if the surrounding roof without rooflights achieves Class B, so should a roof assembly including rooflights).

Practical recommendations

• Define the non-fragility classification required. Avoid use of terms such as “walkable” or “mansafe” - these terms are undefined so can result in use of lower grade products.
• Request specific evidence for any non-fragility claims (a detailed test report, signed by a competent person, or compliance with GN2006/1) and ensure this covers the application/assembly in which the product is to be used: do not rely on general statements.
• For rooflights, method of fixing is critical - always fix the rooflight as recommended and tested. A poorly installed rooflight is potentially as much of a hazard as a fragile product.
• Never wilfully walk on any rooflight. This will encourage dangerous practice as not all manufacturers units are non-fragile and foot traffic may damage the rooflight.

Further Information

Further information can be obtained from the ACR (Advisory Committee for Roofwork) at www.roofworkadvice.info, or from NARM, (National Association of Rooflight Manufacturers) at www.narm.org.uk

Non-fragility of Roofglaze Rooflights