Additional construction costs for a house on a 120k Euro plot

You also forgot the explosive ordnance register, which costs about €2000 including clearance by the probing company. Surveying is significantly more expensive. €3000+ per boundary stone €650. Finally, measuring the house also €700. Furthermore, special use of the sidewalk for construction vehicles with restoration on our side, area 3.5x2m, about €3500. The notary fee is also too low. Unless you do not have to register a land charge. Surely I have forgotten some things, but our property in Hamburg, 530 sqm pipe stem, has already caused these additional costs. Electricity, telecom, cable TV, possibly gas line, are still to come. I have to say we only planned about €30,000 for connections and fees without realtor & notary (without gas), and we need that too.

We have neither paid for the explosive ordnance disposal service nor a sidewalk. However, surveying costs are almost €2000 in total for us. The kitchen is also fine for €10,000.

The earthworks with basement are set significantly too low.

But the OP didn't say anything about a basement, did they?

Still, the 2,000 euros is too little as well.

In Hamburg, clearance from unexploded ordnance must be proven; before that, neither pipes may be laid nor construction may take place. However, this is rather specifically regional.

Explosive ordnance clearance was conducted by IBA Hamburg. For the notary fees, I have used a calculator and have increased the amount for notary and land registry to €3,100.

Since the entire construction area is currently being newly developed, I actually do not expect the increased development costs. A construction road also does not need to be set up. I have already received this information by phone.

I will take another look at the earthworks. Since there is already a lot of digging going on everywhere, I hope that not too many additional works will be necessary.