By Phil Slinger – CAB CEO
Since the Grenfell disaster in 2017 CAB have actively been working across the Construction Industry to communicate and support best practice on behalf of its membership. Whilst it is well known that aluminium itself is not flammable, materials that it can be used with could be flammable and this is sadly the case regarding the ACM that was used on the Grenfell Tower.
The most significant legislative response to Grenfell was the Building (Amendment) Regulations which initially came into effect in December 2018, banning the use of combustible materials in the external walls of refurbished and converted residential buildings with a habitable floor above 18 metres from the ground, (now reduced to 11m). Thousands of leaseholders still face huge bills in getting combustible cladding replaced, although there are now funds being collected from Industry to replace dangerous cladding. The new Fire Safety Bill continues to hold building owners responsible for managing and actively reducing fire risk in multi-occupied residential buildings.
A 2019 government Advice Note on Balconies used on Residential Buildings had an even wider impact, with guidance that applies to all existing residential buildings, stating that building owners “should assess the associated risk of external fire spread and take appropriate action to manage this risk and to ensure compliance with the principle set out in Requirement B4 of the Building Regulations.” This followed some well documented timber decking fires that have propagated across residential building facades.
With work now underway in resolving these issues in existing buildings we should now be constructing new building with a particular emphasis on eliminating the potential external surface spread of fire. Current Building Regulations require new projects must use building envelope materials that are A2-s1, d0 rated or Class A1 under the European classification system in BS EN 13501-1, also known as Euroclass. Currently some elements of the building envelope are currently exempt from this legal requirement, this includes door frames, doors, windows, curtain walls, seals, gaskets, fixings, sealants and thermal breaks. Cladding, spandrel panels and column casings and rainwater goods will fall under the regulations, as anodised aluminium meets Class A1, what about applied coatings on aluminium?
Ultimately, polyester powder coating does not promote combustibility or fire spread when tested to BS EN 13501-1. This is further supported by the testing required for London Underground approval, often lauded as a barometer of fire safety. This requires compliance to EN 45545, where spread of flame is measured objectively (ISO 5658-2) unlike BS EN 13501-1 which involves visual assessment only. Furthermore, PPC smoke production is extremely low or non-existent (s1) with no flaming droplets (d0). On the chart of combustibility, ‘A2-s1,d0’ sits just under the ‘A1’ classification. It is important to assess the cladding system holistically and not just the performance of the constituent parts under BS EN 13501-1.
The predominant fire test for the whole external cladding system is BS 8414. The test itself involves a 9m high wall with a complete cladding installation, including the fixing of panels and insulation. It is therefore a through-the-wall test. When tested to these stringent fire safety standards, polyester powder coated aluminium performs as well as anodised and pre-coated aluminium sheet material.
Currently the facade industry is turning its attention to glazed facades and in particular curtain walling. As with solid cladding there is a possibility that compartmentalisation can be compromised through a non-fire rated curtain wall system, ‘leap frogging’ from floor to floor. At CAB’s last members meeting held in Bristol, Siderise were one of the main speakers during the conference and explained the current thinking behind face safety and where the Industry is headed.
CAB’s own Fire Safety Working Group meet regularly to discuss emerging legislation and comments from experts and businesses across the Industry. Feedback from these meetings and the work of CAB is communicated through to members in the Association’s excellent monthly technical bulletin, known as ‘Insight’. The document keeps members aware of what is happening in the Industry and any member can attend meetings and join in the discussion.
It took a tragedy on the scale of Grenfell to bring about an industry-wide reset of design and specification practices. With CAB’s input, buildings are now being constructed to a much higher standard of fire safety and the UK’s regulations now set a benchmark which other countries are now following. Here at CAB we will be keeping our membership informed of developments and further pending changes in legislation. Why not consider joining the Association and be recognised as being involved in supporting your Industry and helping too shape its future. More information on our website at c-a-b.org.uk
