How to build in flood zone HQ100 EXTREM

that is a good tip, I would be interested in exactly these cosmetic things like dam bars, are they any good yes/no? So if I buy such stuff and the serious case occurs, it should not just be handled by the insurance.

Do not overlook water ingress through the sewer. A backflow flap in the utility room might be insufficient in some cases.

Call the THW about the bars.

However, I strongly doubt that you get more than deceptive security from such things. If anything, better save the money consistently and consciously take the risk.

Who already has experience with this or a good idea on how to solve this as cost-effectively as possible???

The mechanical lifting of the house will be the most cost-effective approved solution if it’s "only" 10k€. Even with a small 500 sqm plot, you already have at least 100m of distance with a waterproofing solution. So you would have to come in under 100€ per running meter including the access solution. That is already a challenge. Take a look at how the Dutch partially solve this: They have a concrete basin under the house, which in turn sits on a pontoon and is guided on steel rods. When floodwater comes, the house lifts guided by the rods. When there is none, it sits there like a completely normal house. It’s also clear that you won’t get this solution for 10k – it is elegant, however, and you can easily plan with 1+x meters. That would be my solution to combine aesthetics and function – I consider it economical but also recognize the increased capital requirement.

Look at how the Dutch partly solve this: They have a concrete basin under the house, which in turn sits on a pontoon and is guided on steel rods. When there is a flood, the house lifts, guided by the rods. When there is none, it sits there like a completely normal house. Of course, you won't get this solution for 10k - it is elegant anyway and you can easily plan for 1+x meters.
That would be my solution to combine aesthetics and function - I consider it cost-effective but also see the increased capital requirements.

WOW, of course, it is 5 times cheaper to repair the damage; if the dam really breaks, it would be a maximum of 60 cm, assuming it is not the maximum water level and the THW is working against it, then it might be 10-20 cm, and that has never happened in the last 70 years.

Anyway, I just have to present something, what exactly is purely a matter of design and I would like to have experiences from those affected.

WOW, of course it is 5x cheaper to fix the damage

I see money as a lever and not as an end in itself. I value quality of life higher. Money comes and goes – lifetime is irrevocably gone. When I think about the quality of life of a family I am friends with, who in the Donau / Vilshofen area had to leave their house twice for a long time after flooding, the pure cost calculation takes a back seat. Of course, one can justifiably and fully understandably see it differently. Those who know the options can usually make a better decision.

if there is ever 10-20cm of water standing in front of the house and even if it should be 60cm, it does not necessarily mean that it is inside the house. And as I said, I have insurance, I am building a solid house, why should I now invest 100,000 € in a concrete basin, apart from the fact that I neither have the money nor will get it. On top of that, the whole construction delay... that could ruin my entire dream. The bank has approved the financing for this specific house with these costs, who knows....

why should I now invest €100,000 in a concrete pool

You are not supposed to. Solution rejected and all is well. Don’t worry about it any further. It would only have been stupid if you later thought: "If only I had known that back then." And that’s what the post was meant to be - an offer of a perspective and not a "only my suggestion is right".