the case is not always like it is with you (but mostly). Especially with all-glass systems (frameless), production is often done in advance. Here, the shell construction must fit within +/- 0.5 cm. Floor and ceiling height can also be precisely planned... Certainly, this is not standard with GUs. We will also have floor-to-ceiling glazing. Glass height 2890 mm. The floor is as high as the bottom rail, the ceiling as low as the top rail. Thus, only glass is visible. Also, the different coverings inside/outside are at the same height. It just has to be planned. It simply doesn’t work if important decisions are made only during the construction phase.