6. Semi-curtain

European standards do not mention the semi-curtain. This concept is mainly French. In Europe, we're talking about curtain walls that pass in front of concrete slab edges, for example, or frames between concrete slabs. However, there is a very common intermediate case that was very well defined in the former XP P28 001 standard. This is the case where the spandrel is made of concrete. In this case, the window frames are installed in front of the concrete (like a curtain wall), and the concrete spandrels are lined on the outside with glass infill, or similar, with insulation over concrete. Once installed, it's impossible to tell from the outside whether this is a curtain wall or a semi-curtain wall. From the inside, it looks like a strip frame.

In reality, they're strip frames, but with special features in terms of fastenings and, above all, sealing - which has to...