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Part One of our series on dispelling the myths about rooflights
Shooting the Myth - ?Rooflights are always fragile?
It�s now 12 years since the Construction Design and Management (CDM) Regulations came into force stating that all roofs should be non -fragile for the life of the building. At the time members of NARM were well aware of the issues surrounding fragility and set about developing designs and specifications for non-fragile rooflights.
As a result, we now have rooflights as strong, if not stronger, than their surrounding opaque sheets, yet, in spite of this people still consider rooflights as fragile. Possibly the biggest sector of professionals still thinking in the past, is the HSE Inspectors. Why?� To be fair to them they still see accidents happening with people falling through roofs, but these accidents generally occur on old buildings erected long before 1992. |
Domed polycarbonate rooflight
under test at B.R.E. to ACR[M]001:2000. |
Reporting accidents � wording can be misleading
Another problem the rooflight industry has to address is the way accidents are reported.� When a person falls through a roof they usually report what the person fell through, e.g. asbestos cement sheet, or rusty metal sheets, or with outer sheet removed - fell through plaster board lining.� They never write - ?went through opaque sheeting?.� However, if the person went through a skylight they just report ?Rooflight?, not a �grp�, �pvc� or �acrylic� rooflight.� Thus all rooflights, regardless of specification, are deemed to be ?the same?.� In practice, nothing could be further from the truth. The material type used and the material type used, specification and fixing method are fundamental to the differing performance levels attainable from what is deemed to be ?fragile? - right through to being tougher than steel !
Most accidents associated with failed rooflights are with PVC or acrylic rooflights which, since CDM Regs, have virtually disappeared from the industrial building market.� Today, the number one products are GRP (glass reinforced polyester) or polycarbonate with sheet strength improved by increasing thickness and material specification.� As specs can vary considerably we would recommend rooflights manufactured by a NARM member. These rooflights can be made exceptionally strong and certainly strong enough to withstand the requirements of ?Test for Non Fragility of Profiled Sheeted Roofing Assemblies� ACR(M)001:2000? - the approved test for non fragility.
Defining rooflife
CDM says that roofs should be non-fragile for the life of the roof but what does this mean? A maintenance free life or�design life, or the actual life of the building remaining upright ?��All roof materials decay with time and weather exposure so roof assemblies will inevitably start to fail and, at some point, become fragile.� Unfortunately we have no means of testing when an old roof has become fragile apart from the ultimate test which is not recommended !
It�s only the rooflight industry that has tried to address this longevity issue.� Profiled rooflights are now available to a range of specifications to provide a range of anticipated periods of non-fragility - be it 10 to 20 years, 25 years or designed for the expected functional life of the rest of the opaque roof.
Whichever specification is chosen, the information should go into the building's ?Health and Safety File? so that future maintenance staff can be aware of the safety issues before going on to the roof.
Only NARM members have addressed non-fragility after the building has been completed. People believe that if you can see through it - it must be unsafe, and if you can't see through it - it must be safe.� BEWARE, for modern designed buildings, the converse is likely to be the truth�!
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