Whilst Cavity Trays do not fulfil a passive fire protection function, their position within the cavity means their fire performance has become an important consideration.
Cavity trays are a fundamental element of masonry construction. They work to direct any rainwater that enters the wall cavity through the external brickwork away from the inner structure, thereby reducing the risk of internal damp and mould. Whilst they do not fulfil a passive fire protection function, their position within the cavity means their fire performance has become an important consideration, especially as we move away from traditional masonry / blockwork structures in favour of cost-effective, quicker-to-erect steel framing systems (SFS).
ADB (England: Volume 1 and 2) Regulation 7 states that for high-rise residential and other relevant buildings over 18 metres, cavity trays (alongside other key facade elements) must achieve an ‘A1 or A2-s1, d0’ classification to EN 13501-1, unless they are between two leaves of masonry.
On 1st June 2022, the government announced further amendments to ADB. This introduced a range of measures, from expanding the definition of higher risk buildings to banning certain materials. This change brought cavity trays into scope of Approved Document B: Fire Safety (ADB) which asks that ‘non-combustible’ or ‘limited-combustibility’ cavity trays are used in SFS builds. At the same time, it also announced an 18-month temporary relaxation which exempts cavity trays from the non-combustible performance requirement in all construction methods, until December next year.
Meanwhile, new cavity tray solutions have been developed that combine flexible aluminium cavity trays with integral, pre-compressed non-combustible insulation. This creates a single-component product that provides reliable quality with several practical benefits.
Firstly, as a single product, they can be holistically tested to ensure an accurate fire reaction classification. This offers both peace of mind and evidence that the product as installed is fully compliant with the regulations. There are also products available that are backed by warranties from major providers such as NHBC, Premier Guarantee and LABC.
They are also obviously much quicker and easier to install than forming the solution onsite— requiring just a cutting knife and sealing tape for joining at details such as corners or windows— with no need to add additional insulation or use sealants.