Calculation of Property Purchase and Renovation

The worst (I find) were the material prices for the standard items, tile adhesive, filler, primer, paint, etc. I would never have thought ...

We started modernizing a house about 40 years old 4 months ago, which turned into a "light" renovation.

Even though architects etc. can estimate it somewhat, surprises cannot be ruled out. We also thought we'd just paint here and there and that it would still be quite okay...
The worst thing I found (find) are the material prices for the standard things, tile adhesive, filler, primer, paint, etc. I never would have thought...
You really need some reserves, otherwise it gets difficult and it’s no fun either. Even though reserves were planned, the fun has already partly gone for me now.