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Class Rainscreen Cladding

A Guide to fire ratings when deciding whether to reclad a building

20th September 2021

Replacing the cladding on a building to meet fire regulations is a topic that has received its fair share of scrutiny recently. When and where to replace cladding continues to drive discussion, which is why, in our latest series of recladding blogs, we look at the question; do you need to replace cladding and if so, what are your options?

Prior to Grenfell in June 2017, to comply with approved Document B, rainscreen cladding on residential buildings over 18m had to meet the minimum requirement of Class 0 when tested to BS476 Part 6 and Part 7, which measures surface spread of flame and fire propagation or, alternatively, Class B-s3, d2 or better when classified to EN13501. However, Approved Document B was considered to be unclear and difficult to manage, meaning that there were multiple routes to compliance. That resulted in many buildings ending up with potentially unsuitable cladding such as those over 18m fitted with Aluminium Composite Panels (ACM) with an unmodified polyethylene filler (category 3).

Grenfell brought these weaknesses into stark reality and following the Hackitt Report in May 2018, the Government announced it would consult on banning the use of flammable material for cladding on high rise buildings in England. The legislation eventually came into force in December of that year and was known as The Cladding Regulations.

Holbrook House, Acton, London Proteus GL

In terms of cladding fire safety, these new regulations stated that; “building work shall be carried out so that materials that become part of an external wall, or specified attachment, of a relevant building are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009” (Regulation 2(5)).

Crucially, The Cladding Regulations, didn’t force owners of existing residential buildings to deal with the issue of unsafe cladding.

In January 2020, new legislation was introduced called ‘Advice for Building Owners of Multi-storey, Multi-occupied Residential Buildings’, which included a clear requirement for ACM cladding with an unmodified polyethylene filler (category 3) to be removed from residential buildings at any height, and when used in combination with any form of insulation. This document contains latest advice from the government on cladding remediation. Effectively it means that if your building has ACM cladding, whatever its height, then it will need removing and recladd, although it is not yet a legal requirement.

The new legislation also stated the government intends to; “introduce a Fire Safety Bill, which will clarify that building owners and managers of multi-occupied residential premises of any height must fully consider and mitigate the risks of any external wall systems in discharging their duties under the Fire Safety Order.”

The Building Safety Bill, which is currently going through parliament and requires every high-rise building in the country to have a designated building safety manager to ensure that those responsible for the safety of residents are accountable for any mistakes and must put them right. This can mean that buildings that don’t meet fire safety standards have to be re clad and government agencies have again identified buildings with unsafe Aluminium Composite Material (ACM) cladding.

The BSB establishes a Building Safety Regulator (BSR) within the HSE to implement the new, more stringent, regulatory regime for higher-risk buildings (defined as residential buildings over 18m. Care homes and hospitals over 18m are also covered at the design and construction stage).

Existing buildings will need to be registered with the BSR and will require a safety case. The Accountable Person (the owner or managing agent) will need to maintain information about the building and submit a safety case to the BSR.

As well as creating a legislative framework, the government has made a £5bn fund available to remove unsafe cladding on buildings over 18 metres, and a growing number of building owners are taking the opportunity to upgrade their assets.

Follow these standard when removing unsafe cladding

Where removal and replacement of unsafe cladding is required, it is important that specifiers and contractors choose cladding that meets the latest fire safety requirements set out in the legislation. To clarify, replacement cladding should meet European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2007+A1:2009. This European classification ranks fire behaviour in seven classes: A1, A2, B, C, D, E and F as well as the materials smoke development (s1, s2 and s3) and formation of flaming droplets/particles (d0, d1 and d2).

Rainscreen Fire Test

Exova WarringtonFire has classified the full range of Proteus systems in accordance with EN 13501 classification. Our latest system classified, Proteus SP, providing a range of insulated spandrel panels for window and curtain walling which now also need to comply to the same stringent standards for notifiable building and classification to A2-s1, d0 under EN 13501.

The A2 classification confirms that the cladding panels are of very limited combustibility and can therefore be used in facades of all heights (including those over 18m) without further testing, provided that all the other materials within the wall (such as insulation) are also A2-s1, d0 classified or better.

It is important that owners determine which buildings require recladding, meaning they fall under scrutiny of the amended regulations.  The regulations apply to a building with a storey (not including roof-top plant areas or any storey consisting exclusively of plant rooms) at least 18 metres above ground level and that “contains one or more dwellings; contains an institution; or contains a room for residential purposes, but does not include a room in a hostel, hotel or boarding house.” It includes residential schools, hospitals, care homes, student residences, for example.

Re cladding a building can be achieved in number of ways, but as the Government’s £5bn fund is limited, economical solutions are generally being considered for the replacement works that need to occur.  Proteus SR (3mm aluminium hook on rainscreen system), Proteus IP (Interlock Panels) and Proteus SP (insulated spandrel panels) have been developed with this market in mind. Tested to relevant CWCT standards and / or EN13501 classification these range of products offer clients and the industry a range of solutions for this evolving market with economy and speed of installation being the primary driver.

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