G-Tray Render News

Grayson launch G-Tray to combat government ban on combustible cavity trays

Building Regulations have been amended to prohibit the use of combustible materials in the external walls of buildings over 18 metres that contain one or more dwellings; an institution; or a room for residential purposes – including student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools. The new Approved Document sets out amendments to guidance previously published in Approved Document B: Fire safety, Volume 2 – Buildings other than dwellinghouses.

The Approved Document takes effect on 21 December 2018. Previous regulations will apply where a building notice or initial notice has been given or plans deposited with local authority before 21 December 2019. The new document states that the external walls should adequately resist the spread of fire over the walls/roof and from one building to another. It also states that all materials that become part of the external wall must be A2-s1, d0 or A1 classified.

Information on European classifications taken from BS EN 13501-1:2007+A1:2009:

Class Definition
A1 Will not contribute in any stage of the fire, including the fully developed fire, or present a smoke hazard
To comply with The Building (Amendment) Regulations 2018 an A2 product must have the highest classification of A2 (A2-s1, d0)
Will not significantly contribute to the fire load and fire growth in a fully developed fire, and further defined through “s” and “d” characteristics
The characteristics “s” for smoke and “d” for droplets are defined as:
s1 Weak or no smoke
s2 Medium smoke
s3 High smoke
d0 No flaming droplets/particles
d1 Slow dropping recorded
d2 High dripping recorded

There are some products/materials that are excluded from the new requirements, these include:

  • cavity trays when used between two leaves of masonry;
  • any part of a roof (other than any part of a roof which falls within paragraph (iv) of regulation 2(6)) if that part is connected to an external wall:
  • door frames and doors;
  • electrical installations;
  • insulation and water proofing materials used below ground level;
  • intumescent and fire stopping materials where the inclusion of the materials is necessary to meet the requirements of Part B of Schedule 1;
  • membranes;
  • seals, gaskets, fixings, sealants and backer rods; 
  • thermal break materials where the inclusion of the materials is necessary to meet the thermal bridging requirements of Part L of Schedule 1; or
  • window frames and glass.

The use of combustible cavity trays between an SFS inner and masonry outer leaf has been banned. To address the requirement for a non-combustible cavity tray, Grayson began work developing a product that provides the durability, resistance to stress, function and performance required for a cavity tray system.

Guidance taken from NHBC Standard Technical Requirement 3 advise that stainless steel is a suitable material for construction of cavity trays. Stainless steel is classified as A1 non-combustible therefore meeting the requirements of the NHBC and the amendment to the building regulations.

In July 2019 Grayson (GB) Ltd launched G-Tray™ – the world’s first stainless steel cavity tray – exclusively available via the Grayson branch network.

Because of its unique design and construction, G-Tray™ complies to both the new standards and all subsequent NHBC guidance notes. It is a tailor-made bespoke solution that is designed and manufactured to clients needs. Available in both grade 304 and grade 316 stainless steel G-Tray™ is suitable for both inland and coastal applications.

For more details on G-Tray™ or Grayson’s other fire rated construction products contact your account manager on 08448 50 40 50

To read more about the regulation update visit: