For over 20 years now rooflights supplied by members of the National Association of Rooflight Manufacturers (NARM) have been designed and tested for long periods of non-fragility, subject to specification, but many other factors can impact on this.
It is often likely to be the case that this is not possible to identify by means of inspection only how strong and non-fragile a rooflight might be, and if in doubt, the whole of the roof including the rooflights should be treated with caution. It is possible that an old rooflight can still be structurally very strong, but deterioration of sealants and the corrosion and/ or loosening of fasteners in the metal or fibre cement sheeting together with the corrosion of unseen internal components can result in unsafe roof assemblies.
