Recently, members of QUALICOAT UK & Ireland have seen a rising number of powder coating specifications that request an A1 classification for combustibility under BS EN 13501-1. When traced back through to the specifier, the origin of this requirement largely stems from property stakeholders who are misguidedly attempting to mitigate their risk by exceeding the current guidance, standards and legislation. This can add both complexity and costs to projects without any benefit or reduction of risk.
This cautious approach is in response to the fire that destroyed Grenfell Tower in 2017 and the subsequent independent review of building and fire safety regulations.
Which classification is the right choice?
The Government implemented an amendment to the Building Regulations that requires testing and conformance to BS EN 13501 ‘Fire Classification for Construction Products’. Cladding must achieve either an A1 or A2, s1-d0 classification.
The regulation currently has specific enforcement requirements, such as banning the use of combustible materials in buildings over 18m high (11m in Scotland, effective October 2019). This includes apartment blocks, care homes, residential schools, hospitals and student accommodation.
As a result, the removal of aluminium composite panels (ACM) containing flammable cores from 435 high-rise residential tower blocks across the UK has been enforced. However, it is estimated that there are a further 2000-plus high-rise or high-risk buildings that have combustible material on the facade. All of which need replacing. Therefore, it is little wonder that there is a hesitancy with certain specifiers, including local borough councils, to approve non-A1 rated materials.
Yet there are important factors to consider before committing to this blanket specification.
Fire testing – polyester powder coating
The updated Building Regulation to BS EN 13501-1 is applicable when materials become part of an external wall of a building. These materials must achieve either an A2-s1, d0 or A1 classification.
Architectural polyester powder coating (PPC) must achieve the standard requirements of BS EN 1501-1 to meet Approved Document B (Fire Safety). To do so, it must pass four individual tests, the results of which give the overall classification. The tests are EN 13823 – Single Burning, EN 11925 – Ignitibility, EN ISO 1182 – Combustibility and EN 1716 – Calorific Value. The final test differs from the others as it assesses the powder in its raw state.
After all four tests, PPC achieves a A2-s1, d0 classification when applied at industry-standard film thicknesses. It does not contribute to fire, there is little or no smoke production and there is no flaming debris.
It is also worth highlighting that PPC manufactured and supplied in Europe comprises no solvents, no heavy metals and no volatile organic compounds in its formulation. This means that no toxic fumes are emitted in the event of a fire.
Yet, with A1 now the desirable classification for many specifiers, what does this mean for PPC?
Busting the A1 myth
To achieve an A1 rating, PPC must meet certain criteria. The calorific value must be <2MJ/m2 in accordance with EN 1716. In the single burn test (EN 13823) the total heat release, total smoke production, fire and smoke growth rates must be within the limits prescribed. Furthermore, there should be no lateral flame spread, flaming droplets and sustained falling particles in EN 13823.
To satisfy this, PPC would need a lower level of organic content. To achieve this, either the applied thickness needs to be lower than industry requirements or the ratio of organic and non-organic materials in the formulation would have to be significantly altered.
However, changing the percentage of organic compounds (typically around 50%) would negatively impact the overall performance of the coating. There would be a loss of colour, gloss degradation and chalking of the film, for example, after only a short period of exposure. Leading to costly implications for building owners – either leave as they are or be forced to re-coat or replace.
A2-S1, d0 classification suffices
There is clear and tangible evidence that when applied at standard industry thicknesses, architectural PPC achieves A2-s1, d0 classification. This is sufficient to comply with amended Building Regulations 2010 (Approved Document B: Fire Safety) November 2018 and accepted as providing the necessary protection from the surface spread of flames on high-rise and other legislated buildings.
Ultimately, PPC does not promote combustibility or fire spread when tested to BS EN 1501-1. This is further supported by the testing required for London Underground approval, often lauded as a barometer of fire safety.
QUALICOAT UK & Ireland firmly believes that the perceived reduction in risk is not necessarily mitigated by moving from A2-s1, d0 classification to A1.
Irrespective of the classification achieved in BS EN 1501-1 tests, it is critical that the complete cladding system is specified, configured and installed correctly.
Future-Proofing Facades conference – FREE to attend
To explore this topic further, register for the QUALICOAT UK & Ireland conference 2022 on 14th June at the Building Centre, London. Naveen Sandhu is one of many industry experts in the speaker line-up, including keynote speaker Maxwell Hutchinson – formerly the President of the Royal Institute of British Architects. This is a ticketed event and free to attend. Register via the website below. This event is sponsored by Barley Chalu, Chemetall, Interpon, Jotun and Vertik-Al.
Akzo Nobel Powder Coatings is a QUALICOAT-approved system supplier. Naveen Sandhu is the company’s QUALICOAT UK & Ireland member representative.