Tree roots vs XPS basement insulation

The roots are also different depending on the tree. As a rule of thumb, there is "root zone like crown", for figs one would have to research whether this also applies. In practice, it can look different, for example if you have a leaking gutter/drain, it will be wetter there and the roots will concentrate more ;)

My dream would be for the thing to grow about 4-5m high and partially shade the children's room from above in the summer. Then I wouldn't need to fully close the blinds during the day.

But remember that the thing ALWAYS shades the room. So also in summer mornings and evenings, when you would like some sun and brightness in the room, also in spring and autumn when you normally wouldn’t want shading. And even if it doesn’t have any leaves it still blocks light in the dark season.

If I were to plant a tree that close to the house, I would put a root barrier in front of the insulation. There are root barrier sheets for bamboo in different thicknesses, which I would use.

But remember that the thing ALWAYS shades the room. So also in summer early in the morning and evening, when you like to have some sun and brightness in the room, also in spring and autumn, when you wouldn't shade. And even if it doesn't have leaves, it still blocks light during the dark season.

However, this is very limited for a fig tree. The fig tree is airy, not heavily branched, and also does not have dense foliage. Depending on the tree, a fig can even look "scruffy." If you like trees, I wouldn't worry about permanent shading. Most houses have sufficiently large windows.

I grew up with a hazelnut bush in front of my window (the bush of course grew faster than I did). I really liked the beautiful atmosphere of leaves and the rustling of leaves in front of the window. I would like to have that again now, but unfortunately it's not possible.

This is very limited with a fig, though. The fig tree is airy, not so heavily branched and also does not have dense foliage. Depending on the tree, a fig can even look "pimpfig". If you like trees, I wouldn't worry about the permanent cladding. Most houses have sufficiently large windows.

Maybe there are different varieties? An acquaintance has such a tree that has closed foliage during the growing season.

If he gets too wild and the children still want light in the children's room, the saw has to come into play. Don't worry. If I plant a tree now and children come in the next 3-6 years, I am not worried at all that they won't be able to look out the window anymore. :D