The HSE’s ‘Health & safety in roof work’ publication HSG331 highlights the fact that “Roofers account for 24% of all workers who are killed in falls from height while at work. Falls through fragile materials, such as rooflights and asbestos cement roofing sheets, account for more of these deaths than any other single cause. There are also many serious injuries, often resulting in permanent disabilities.”
It should be said in the defence of rooflights and asbestos cement, prior to the early 1990’s, these products were manufactured and marketed as fragile, since it was not required then that they should be non-fragile.
Roofing accidents occur across the whole range of roof work from the simplest repairs to large-scale construction projects. Whatever the reason for accessing a roof, there is simply no room for complacency regarding any aspect of roof work, or in the specification and design of roofs and roofing products.
As the industry body representing the UK’s rooflight industry, NARM is committed to communicating and encouraging best practice among designers, manufacturers and installers of rooflights, to play a part in reducing the incidence of roof work related accidents.
Understanding and classifying the non-fragility of rooflights is a complex subject and NARM has worked closely with the ACR – Advisory Committee for Roofsafety (formerly the Advisory Committee for Roofwork) in this respect, for many years.
The membership of ACR is made up of nominees from the major roof working federations and associations who, together with the HSE, provide the technical experience of many years of involvement in working on roofs. It is this body that has developed the test method by which rooflights and other roof assemblies are classified for non-fragility in the UK. This has been published as part of the ACR’s ‘Red Book’ ACR[M]001.
The ACR[M]001:2011 test for non-fragility
The ACR[M]001 test can be applied to any roof assembly and is 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 is always carried out on a specified test rig under
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 the highest rating, Class A.
To achieve Class A, there must be no significant damage to the assembly. Any damage to the surface protection which could accelerate the degradation process should be seen as sufficient to withhold a Class A rating. This could include microscopic scratches and scuffs caused by the impactor.
The view of most competent testers of typical roofing products, including rooflights and profiled roof sheets, is that damage is always done during the test. Fixing holes may become enlarged, or the weather protecting coating on a product will be damaged – even if not apparent to the naked eye.
In the event of damage to fixing points or UV coatings, it is inevitable that this will be a catalyst to product degradation and thereby the period of time that the assembly will remain non-fragile will be reduced.
For this reason, reputable manufacturers of rooflights and roof sheets never claim an ‘A’ rating – even in the event of the assembly being awarded an ‘A’ rating by an independent testing organisation – as was the case recently with one NARM member company.
What is often not understood by designers, roofers and building owners is that the ACR[M]001 test has 3 limitations which have a bearing on the performance of installed assemblies:
1. Tests take place on a prescribed test frame to simulate generally the worst case scenario of a roofing assembly. Assemblies are not tested on the actual roof and should never be tested on the roof after the passage of time to see if they are still non fragile.
2. Tests take place where all the components, fixings, mastic sealants and the structure are new. It is the total assembly that is tested, not just a product on its own.
3. The ACR[M]001 procedure is clear that there is no measure of time after installation. The assembly is only deemed to be non-fragile when new and does not try to assess when it will become fragile with time.
There is a general misunderstanding in the building sector including many roofers, that a non-fragile roof is for all time. All roofing elements, regardless of what they are, will deteriorate with time and ultimately the structure will become fragile. This timeframe will be shorter if the roofing specification has been weakened by using cheaper materials or the supporting structure is inadequate.
What is clear is that a non-fragile roof will become fragile with time. It is just a matter of when? Therein lies the question that manufacturers are always being asked.
The simple answer is “we do not know”. There are too many variables to provide a clear cut answer. Are the fixings supplied to specification and have they been fixed correctly? How has the building suffered from climatic conditions or local environmental conditions? Was there any damage to coatings during installation? Or has any damage occurred since then, during maintenance or repair operations?
Our advice is simple: Whatever the ACR[M]001 classification, it is safest to adopt the ‘belt & braces’ approach to Health & Safety: that once the building is completed and handed over for commercial use, then any further work on the roof should be carried out on the assumption that the roof may be fragile and the appropriate safety measures put in place.
Every group within the construction sector – from product manufacturers to specifiers, contractors and developers – is in the same boat. We’re all under increasing pressure to provide competitive solutions. We must never, however, lose sight of the fact that safety must not be compromised for cost reasons. If we all take a responsible attitude, we’ll be on a level playing field and above all else, lives will be saved.
A simple and easy way to ensure relevant UK quality standards are met, is simply to specify rooflights from NARM member companies. A prerequisite of NARM membership is that rooflights must be fully compliant with UK standards and legislation.
controlled and safe conditions.