Why testing matters: the hidden risks in SFS-to-steel connections

And when it comes to steel framing systems (SFS) fixed to fire-protected structural steel, those connections carry more potential risk than you may realise.

That’s why Remagin, working with Promat and Siniat – two other Etex Group brands – has developed a fully tested solution focused on one of the most overlooked parts of façade design: the fixings.

Specifically, the Remagin team looked at how fixings behave when SFS heads connect to fire-protected steelwork. Because the integrity of the whole system can depend on this single, critical detail.

The challenge with protected steel

Structural steel must, of course, be protected against fire to prevent catastrophic failure. Fire protection often takes the form of boarding systems, such as those offered by Promat and Siniat.

But when you introduce boards between steel beams and the SFS head track, you also introduce the potential for increased rotational movement. That movement creates higher bending moments on the fixings, and can lead to fatigue – especially under dynamic loads such as wind pressure.

Historically, this interface hasn’t been fully tested under realistic conditions. Which means project teams have had to rely on educated guesses and assumptions, rather than rock-solid evidence.

To fix this oversight, Remagin carried out independent mechanical testing on a range of screw types and configurations. The goal was to understand how fixings perform when placed between SFS heads and protected structural steelwork.

The testing looked at failure loads, types of movement and mechanical resilience. Cyclic loading tests were also carried out to simulate wind pressure on SFS infill wall panels – mirroring the kinds of stresses buildings face in real life.

The results gave critical insight into how each fixing performs under different conditions. So rather than using a one-size-fits-all approach, Remagin can now specify screw designs and configurations that are tailored to individual projects.

Fire testing at the system interface

Mechanical performance is one side of the story. Fire resistance is the other.

The mechanical tests were followed by bespoke fire resistance testing. This testing focused on how wall systems behave when attached to encased steel beams – in particular, the interface between the SFS infill wall and the boarded structural steelwork.

The results confirmed that fire integrity and insulation were maintained at that critical junction. This means designers can have confidence in how the system performs as a whole, and not just how each part performs in isolation.

One reason this kind of testing is so important is that other commonly used approaches – such as intumescent paint – can introduce risk if not properly evaluated

Directly fixing SFS into intumescent-painted steel may be convenient, but it invites risks. The insulation and framing must allow room for the paint to expand under fire conditions. And when structural steel aligns with a fire compartment line, the temperature needs to be kept lower than many paints activate at. These challenges make case-by-case assessment essential.

By providing hard data gained through robust testing, Remagin, Promat and Siniat have  helped design teams to avoid these pitfalls and de-risk their projects from the outset.

A strong connection

This unique collaboration between Remagin, Promat and Siniat has resulted in a complete, tested solution for one of the most critical – but often neglected – parts of façade construction.

By looking closely at where systems meet, and by testing those points under real-world conditions, they’ve given the entire industry a clearer picture of risk, alongside a proven way to reduce it.

In construction, it’s easy to focus on the bigger picture. But often it’s the small connections that are the unsung heroes of a project.

For more information on protecting the structural integrity of steelwork go to www.promat.com/en-gb/construction/structural-protection/