Concrete offer for turnkey only with land ownership?

Without a soil survey, calculation is impossible, of course. But even then, my excavation contractor didn’t want to commit to any amount of excavation for the basement. I stick to my point: you only know the exact costs once the excavator’s invoice arrives. Not a minute earlier. Then they excavate 50 cm more on a 13x11m area and you immediately miss 2k€ of your budget. You have no idea how much I hoped it wouldn’t be 300 or 400 cubic meters. In the end, it was only 240 cubic meters. But you just don’t know beforehand. You can still do a lot of recalculating based on height data.

However, some construction companies are now refusing in advance to make a concrete, turnkey offer because we do not yet have the mentioned plot of land.

What are your experiences with this? Similar?

I was with two providers and told both that we would purchase the property soon.

We had a detailed conversation.

Today, after 4/5 weeks, I have both offers in great detail.

I think it depends on how credibly you can convey to them that you will actually buy a (preferably explicitly named) property.