The shape of things to come
Text: Roman Felden
Just like a proud new dad — at RAICO: the latest member of the company’s family of curtain wall systems is the THERM+ FS-I. Michael Kaufmann and his team have developed this steel curtain wall system using screw-in tubular profile sections. It is in fact a multi-parent affair, albeit with “custody” awarded to Mr Kaufmann. So what were the team’s thoughts as they planned the design?
“We wanted to create a steel curtain wall system with integrated screw channel, for combining with our THERM range“, explains Mr Kaufmann, before adding: “This gives architects greater freedom of movement to design, with these high- load-capacity system components at their disposal, and the people responsible for assembly are no longer obliged to put together the rigid-frame steel structure with welds, bolts or rivets. They can now screw the pressure profile directly to the structural system.
He adopted the original idea in his role as team leader for curtain walls, and lovingly nurtured the fledgling project that resulted. “I continued to develop, and then implement, the basic idea along with my team. So I am perhaps a midwife rather than a single dad.”
An uncomplicated birth. Right from the start, Kaufmann and his team were at the heart of the THERM+ FS-I project: a functional groove with correspondingly matched, screw/clip-on profile. When it came to fixing the pressure profile and structural system directly to each other, the key question was how to design the groove into which the screw is anchored. It took some time to determine the exact size of the gap that would allow easy insertion of the screw into the clip opening, while eliminating any play between the elements concerned. Mr Kaufmann even had to develop a new screw for the purpose. It had to be hard enough to self-tap into the steel profile and also highly resistant to corrosion, as its head may be exposed to the weather. “We have opted for a special screw that fulfils both of these requirements”, he says.
Another clue lies in the innovative T-connection system: The standard SC connector for mullion and transom profiles has a variably adjustable fixing element designed to match internal tube-diameter tolerances. It can be transported easily, and is suitable for use with threaded tubes and standard press-on steel profiles, and also as a screw-on expansion transom and for subsequent transom installation. The SCL ladder connector can also be screwed in to provide contact pressure.
The newly born FS-I is kept nice and dry with a cover seal to stop surrounding water penetrating the screw. It is also largely impervious to temperature changes, as its one-piece plastic profile conducts considerably less heat than one made of metal. Various insulating blocks based on the existing THERM+ system can be used, depending on the required heat insulation and desired heat transfer coefficients. FS-I is thus certified for use in all “passive house” systems – with maximum thermal insulation of up to Uf=0.77 W/(m2K), with screw factor included.
“And it’s also really good to look at”, says the proud joint parent. He is referring here to the reduced radii of the profile tubes, which give the FS-I its sharp-edged appearance. Architects appreciate this characteristic, because it allows them to create seamlessly merged glass façades and curtain wall profiles.
Confidential sources report that Mr Kaufmann and his helpers have already wet the new baby’s head with a well-deserved beer or two. This was outside working hours of course, as midwives aren’t allowed to drink on the job.
What is Therm+ FS-I capable of?
This curtain wall system with integrated screw channel is compatible with all other THERM systems. Architects can employ it freely with a massive range of dimensions and wall thicknesses, and use its sharp-edged look to create elegant, seamlessly merged glass and curtain wall profiles. Installers no longer need to worry about welding or riveting, as the FS-I system lets them screw the pressure profile and structural system directly to each other. The system also includes two different T-connectors for single-bar and ladder installation.