How expensive is flood-adapted construction?

Hello,
we have an offer for a plot of land located in the HQ100 area.
We like the location and size. However, after extensive research, I could not find any information about the additional construction costs, only that many measures are necessary.

Does anyone know from experience how much % or similar one has to factor in when building a house in an HQ100 area?

Thank you very much and best regards

Hello,

unfortunately, I can't say anything about the costs. But basically, you can definitely forget about the basement and I would then recommend that you build on stilts....

Flooding is an adventure and a risk, you really have to be willing to take it. I would also definitely plan some "buffer" in terms of height, so that you don't get surprised by a flood wave like in Bavaria and Saxony.

Do you really want to build there?

On the one hand, it may be that you cannot get any or only very expensive building insurance there.
On the other hand, it may be that banks value the house lower because houses in the flood zone fetch a lower market price.

Hello,

we definitely want to get detailed information beforehand. (Fortunately, we are in no hurry at all) 'Flood zone' sounds dramatic at first. According to the certificate from the municipality, 2/3 of the parcel is in an HC100 area (i.e. on the edge) that could be flooded once in 100 years. These flood zones (ÜSG) must be designated by cities and municipalities. You can also take a look at the ÜSG maps on the Internet at the respective state offices (these have been created gradually since 2014). Very interesting!

I would definitely talk to the direct neighbors of your desired property. How high were the last "major" floods, how often did they occur, etc. If it is "only" the garden that gets flooded, and maybe only every 5 years, then it shouldn't be too dramatic. In our case, part of the garden is also in the HQ100 area. However, at most 1/3, and we don't have any buildings there, really "just" the garden. (we also moved the house up a bit because of the HQ100 line)

I would like to link readers here to a contribution to an article on the internet, but that is not allowed.

Therefore, please copy "Themse Island Floating House" into Google and look at the first post in the Dezeen Magazine (there are more sources about it). That will probably exceed your budget, but it offers absolute flood protection up to 3.60 meters in height...

Sorry, unfortunately I can't contribute anything more useful.