Manually operated roller shutters - space above the window

Hello,

I would like to have exterior roller shutters installed. These will be top-mounted roller shutters that are mounted outside above the window. I would like manually operated shutters. The employee of the company who took the measurements told me that this is not possible because there is not enough space above the window.

In the upper floor, my windows actually go almost up to the ceiling. There is only 7 cm of space up to the ceiling. Is it true that there is not enough space to install manually operated roller shutters?
Unfortunately, the man could not explain well why this is the case and I had the impression that he would rather sell the more expensive electrically operated ones.

Can someone here tell me how much height above the window is needed to install top-mounted roller shutters that are to be operated manually?
Thanks in advance!

Well, roll something flat, what do you think the diameter will be?

I don't know how this is done technically. The rolled-up tape is certainly not thicker than the rolled-up shutter at the top of the box. Where is the rolled-up tape located?

Belts themselves should also be reroutable - I lack the overall idea of the installation situation - especially one where it should only depend on the belts and the box installation would be unproblematic.

Our manually operated built-in roller shutters have exactly 20cm above the windows ...

I finally got around to taking a photo. Here you can see that there are only a few centimeters above the window until the ceiling starts. Apparently, that's not enough for manual roller shutters. :(