The Problem to Solve

With recent emphasis on fire integrity, there have been some calls for a cavity fire barrier to be put in around steel balcony arms. This is an awkward detail, and fire engineers find it difficult to work up a detail that is adequate to meet the intent of the Building Regulations Part B. The intent was to find a generic solution that could be applied to all steel arm penetrations and be certified to withstand up to 120 mins of fire under standard test conditions.

The need is to meet Approved Document B of the building regulations – Section 10 – Protection of Openings and Fire-Stopping, and in particular, parts 10.1 – 10.3 and 10.17, 10.18. Approved Document B Section 9 – Concealed Spaces (cavities), in the building regulations deals with fire cavity barriers which is what the stub or arm is breaching and hence the need for a firestopping measure.


StubGuard has been launched as a standard methodology that can interface with fire stopping details at the slab edge in a consistent way, which is certified to EWCL5. It is a mineral fibre-based wrap-around shield that can be applied to all arms and is compatible with facade details in current use as well as being water-resistant.

It consists of a dense fibre machined block with a reinforced aluminium foil outer skin. It should be used as part of a fire stopping strategy and incorporate fire cavity barriers to each side of it to provide a certified solution for the project.