Building a model house - small changes, unintended side effects

Whatever the individual names of the components are. For me, the beams run from eaves side to eaves side. A staircase is installed perpendicular to the beams, so the staircase must touch the beams. When going upstairs, you have to somehow pass the crossbeam, otherwise you would literally have a board in front of your head. But since shed light on this for me with the note "stich beam, replacement beam," this was very helpful. I know about this replacement thing you do with a roof window when beams (ridge-eaves) are in the way. I just wasn't aware that you can do this with a pull-down attic ladder as well. And I have to honestly admit, although your writing style is somewhat special, I read your text several times but was no wiser than before. Now, having reread it and with the word "Auswechslungen" along with the info from the original poster, I had the AHA moment.

And I have to honestly admit, although your writing style is somewhat special, I read your text several times but was still no wiser than before.

My editor often says something similar ;-)

For me, those were beams running from eaves side to eaves side.

Actually not, those would be one level lower (between ground floor and attic - though not here, because as far as I know there is a concrete ceiling here). The ceiling discussed here is between attic and roof space, so above the eaves line.

Beams (ridge-eaves)

Those would be called rafters. And they would belong to the roof structure, but not this ceiling.