Understanding the changing fire performance requirements of cavity trays in masonry facades

The way we construct masonry buildings has developed, with many projects moving away from traditional non-combustible blockwork inner leaves in favour of cost-effective, quicker-to-erect steel framing systems (SFS). This has meant reconsidering the fire performance of elements installed within the cavity, including the cavity tray

While cavity trays do not fulfil a passive fire protection function, Approved Document B England: Volume 1 and 2 (ADB) Regulation 7 states that for high-rise residential and other relevant buildings over 18m, they (alongside other key facade elements) must achieve an A1 or A2-s1,d0 Euroclass rating under EN13501- 1, unless they are installed between two leaves of masonry.

On 1 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. At the same time, it also announced an 18-month temporary relaxation, ending in December 2023, which exempts cavity trays from the non-combustible fire performance requirement in all construction methods.

Industry found securing non-combustible approaches ‘challenging’

This has been done in response to the 2020 consultation – Review of the Ban on the Use of Combustible Materials in and on the External Walls of Buildings. The responses suggested that the industry had been finding it challenging to find suitable approaches to ensure non-combustibility. Many had been resorting to bending sheet metal and packing it out with non-combustible insulation onsite.

The relaxation is intended to give the industry time to catch up in terms of innovating new
cavity tray solutions that will comply with the regulations. However, in the two years since the consultation, solutions have been developed that already tick all the boxes.

Futureproof solutions to fire performance

New cavity tray solutions are now available 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.

As a single product, they can be holistically tested to ensure an accurate fire reaction classification. There are also products available that are backed by warranties from major providers such as NHBC, Premier Guarantee and LABC.

Practically, 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.

Meeting the right requirements now

While we still have 12 months to go until the exemption is lifted, the government has already stated that it intends to “ensure that non-combustible cavity trays are used in the external walls of buildings where they are readily available”. Solutions that not only meet this fire performance requirement but are backed by relevant warranties and assurances can help to achieve full compliance with the regulations from the outset, ensuring a safe and effective building built for the future.

*Please note: This is a commercial profile