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Cavity Trays: Why Stainless Steel?


Damp within buildings is one the most expensive – and not to mention problematic – defects to correct.

That’s why it’s standard practice to include damp proofing as a preventative measure during the construction phase. Doing so helps stop moisture from accumulating within the cavity and damaging the surrounding brick/blockwork and structural components.

When including damp proofing, ACS recommends the use of stainless steel cavity trays wherever possible.

What is A Cavity Tray?

A cavity tray is a type of damp-proof coursing (DPC) that crosses the cavity and helps draw moisture away from the internal leaf of a cavity wall. These combine to form a gutter and helps expel water through a weep hole, commonly positioned in the outer leaf of the wall.

These trays then form a gutter that expels water through a weep hole, commonly positioned in the wall’s outer leaf.

Why Stainless Steel?

Since ACS’ formation, stainless steel has been the go-to material that we use – it is in our name after all! As a material, stainless steel has many benefits, including excellent corrosion resistance and strong tensile properties. It is also non-combustible, something that’s very important today.

PD 6697:2019 states that in buildings exceeding three stories in height if a product is in contact with or embedded in an external leaf of a cavity wall, then its composition should be limited to approved materials.

Stainless steel is an approved material. Other metals and composites are not.

Aside from regulatory approval, using a stainless steel cavity tray offers other benefits. As a non-combustible material, it is classed as A1; it has a high tensile strength that does not diminish over time, it is not affected by acidic or alkaline mortars. Importantly, it is also easily detectable and allows site inspectors to check for the presence of stainless steel cavity trays without the need for visible access.

Additionally, by ensuring consistency of material within the cavity, you can eliminate the threat of bi-metallic corrosion weakening vital structural components.

Finally (and this is a very important point), stainless steel is an environmentally friendly material. 85% of the steel used in ACS-manufactured cavity trays is recycled and at the end of its lifespan, the entire system can be recycled.


ACS manufactures a stainless steel cavity tray system, G-Tray™.

On launch, it was the world’s first A1 non-combustible stainless cavity tray, making it fully compliant with the updated regulations surrounding materials within cavities and the use of steel framing systems (SFS).

For more information on G-Tray™, please visit this link.

Other resources

1. What Are the Benefits of a Two-Piece Cavity Tray?
2. G-Tray’s Thermal Conductivity Is Typically 3x Less Than Zinc Alternatives
3. Zinc Coils Used as a DPC or Cavity Trays?


Article originally published on 26th February 2021