Very much so. However, the price gap is too wide for the basement to be interesting. We would also have to refinance for the basement - which we wanted to avoid.
The 35k would be so worth it to me for the basement.
If it’s financially possible, of course, otherwise it’s unfortunately pointless.
We were also faced with this question! 35k€ for 70 sqm of living and usable space is definitely worth it. Also financing afterwards if the budget isn’t super tight. 15k€ for soil and gravel is totally a mess. If it’s not super tight, do it. That only means paying it off 3 years longer.
No - these are additional monthly burdens, as the supplementary loan will have a minimum repayment. Furthermore, we would then have to make compromises in the layout that would affect our daily life in the house.
The basement would burden us in every respect - however, the 15k would not.