Build a 2nd house and sell the 1st one - How to finance?

cool that you are so honest...

What do you mean by continuing to run [weiterlaufen lassen]?
The financing is tied to you and the old house ... neither can the buyer take over your financing nor can you transfer the financing to another house ...

Change of property may already be possible. However, current market conditions probably cannot be expected.

If you sell the house for 700k, where does the delta come from to buy a new larger house on a larger plot? It's not just your house that has magically increased in price; the land and construction costs have as well.

Yes, that is perhaps factually possible but not worth making an object change...

but you should best talk to your bank about it...

Do you already have a new property in prospect?

If the old house brings in 700k, then you will hardly get a new better one for 700k either, right?
Do you already have something concrete (land?)?
At least we don’t get much luxury for 700k now. The prices are no longer what they were in 2018.

By the way, I know 2 acquaintances who bought the house 1 year before handover.
For us, for example, that wouldn’t have been a problem either, since building a house also takes more than 1 year.

Otherwise, I can only agree, talk to the bank.

...
So basically enlarge and improve ;-)
...

Do that a few times and eventually you end up at Villa Cullinan.

It is not uncommon in desirable locations - friends of ours have been waiting almost one and a half years for their house. The current owner wants to move when she retires and has planned this well in advance.