Floor plan of a flat-roof house on a slope

You don't save 50K€ by adding a centimeter here and a centimeter there. For that, you would rather have to change the plot or reconsider the desire for three floors. Even with supposed prior qualification, I consider self-awarding to be madness. In this price range, it becomes exciting to find a bank that goes along with it.

50 thousand is already something big. I don't see that being saved just anywhere. On the contrary, I rather fear that something will be added here and there.

We saved about 10 grand because we did the electrical work completely by ourselves. My husband is an electrician. But otherwise? Where else do you want to save?

This is not a small house. It's 3 floors on a slope! Uff.

That only works if you save one floor. I would try that anyway. A bit more space, but cut one floor. The constant running up and down the stairs is annoying.