I am currently in the building permit / planning permission process and just found out through a call to the building authority that my property is located in the HQ100 EXTREME risk zone, so I have to take flood protection measures. This requirement has apparently been in effect since 2018 in Baden-Württemberg.
To explain: HQ100 EXTREME means there is a levee protecting my site next to the Danube River, but this levee could break (which seems very unlikely...). Because of this, I need to implement additional flood protection, whatever that may specifically involve. The exact wording states:
“At locations in risk areas outside designated flood zones, where no local land-use plan exists, construction projects may only be built or significantly extended using building methods adapted to the specific flood risk, according to generally accepted technical standards, provided this type of construction is technically feasible given the nature and function of the structure.”
I am building a solid structure without a basement, and my finished floor level is 61cm (24 inches) below this theoretical extreme flood level. I do not want to raise the ground level further. Although this would be technically possible, it would be expensive and would not look good.
I spoke by phone with the responsible official about whether I could build a wall around my property as a possible solution. She said she wasn’t sure if walls that high would be permitted there and reminded me to consider the entrance driveway. She recommended building 81cm (32 inches) higher for safety, but 61cm (24 inches) might be acceptable. However, I got the impression she wasn’t very knowledgeable. Maybe installing barriers or flood gates on the doors could work – I have seen sliding flood barriers online. Overall, this is really frustrating as none of the more than 100 houses nearby (all built before 2018) have anything like this, there has never been an extreme flood, and I think potential damage would probably be less than the cost of these measures. I also have insurance that costs an additional 100€ per year for flood coverage. To be safe, I will probably install my heat pump about 0.5m (20 inches) higher.
Does anyone have experience with this or a good idea on how to solve this as cost-effectively as possible?
To explain: HQ100 EXTREME means there is a levee protecting my site next to the Danube River, but this levee could break (which seems very unlikely...). Because of this, I need to implement additional flood protection, whatever that may specifically involve. The exact wording states:
“At locations in risk areas outside designated flood zones, where no local land-use plan exists, construction projects may only be built or significantly extended using building methods adapted to the specific flood risk, according to generally accepted technical standards, provided this type of construction is technically feasible given the nature and function of the structure.”
I am building a solid structure without a basement, and my finished floor level is 61cm (24 inches) below this theoretical extreme flood level. I do not want to raise the ground level further. Although this would be technically possible, it would be expensive and would not look good.
I spoke by phone with the responsible official about whether I could build a wall around my property as a possible solution. She said she wasn’t sure if walls that high would be permitted there and reminded me to consider the entrance driveway. She recommended building 81cm (32 inches) higher for safety, but 61cm (24 inches) might be acceptable. However, I got the impression she wasn’t very knowledgeable. Maybe installing barriers or flood gates on the doors could work – I have seen sliding flood barriers online. Overall, this is really frustrating as none of the more than 100 houses nearby (all built before 2018) have anything like this, there has never been an extreme flood, and I think potential damage would probably be less than the cost of these measures. I also have insurance that costs an additional 100€ per year for flood coverage. To be safe, I will probably install my heat pump about 0.5m (20 inches) higher.
Does anyone have experience with this or a good idea on how to solve this as cost-effectively as possible?
H
hampshire21 Jun 2020 09:44Bookstar schrieb:
I would just ignore it completely; a dam does not fail.That’s really good. In my opinion, building in former floodplains is not very wise. For me, it’s less about individual behavior and more about societal organization.
hampshire schrieb:
That’s really good.
I don’t think building in former flood zones is very wise. For me, it’s less about individual behavior and more about societal organization. Well, I believe that building in already developed areas will become increasingly important in the future, and I think that’s the right approach from a societal perspective—not always developing new housing estates on greenfield sites. However, this completely misses my point. If someone is a millionaire and can choose plots however they want and also has an unlimited budget, then they probably wouldn’t even be here in this forum.
I wouldn’t say that. Take a look at some projects here. I don’t know how you could implement it without compromising the underlying structure.
But I understand your point; that shouldn’t be the standard.
What I think is that your decision is probably already made. You might now be looking for someone to support your choice.
At this point, however, it could be difficult because likely not many people have faced the same situation.
Weigh your options and decide (if you haven’t already) and do what you believe is right.
From my perspective, there isn’t much else you can do.
But I understand your point; that shouldn’t be the standard.
What I think is that your decision is probably already made. You might now be looking for someone to support your choice.
At this point, however, it could be difficult because likely not many people have faced the same situation.
Weigh your options and decide (if you haven’t already) and do what you believe is right.
From my perspective, there isn’t much else you can do.
hampshire schrieb:
I don’t think building in former floodplains is really a smart idea. For me, it’s less about individual behavior and more about how society is organized.So by that logic, a large part of the Netherlands should probably be dismantled... But you’re right, the risk and the effort to minimize it will only increase with climate change.
H
hampshire21 Jun 2020 21:42Haus² schrieb:
So, most of the Netherlands should probably be demolished afterwards... It is always a question of alternatives and circumstances. These are quite different in large parts of the Netherlands compared to Bavaria.
HausiKlausi22 Jun 2020 00:38Regarding walls: I experienced the 2002 flood on the Elbe River at my parents' house in Saxony. What I witnessed made it clear once again: water has a force (and finds ways) that you would never expect. Four-meter (13 feet) pillars were washed away like toys. These are forces that a "wall" cannot even come close to holding back. Besides, the water also comes from below (groundwater layers). Another lesson is that a dam breach is by no means "unlikely."
When exactly that happened, it was the end of a residential area that was never rebuilt. I cannot draw conclusions about this from a construction engineering perspective, as I am not an expert. But one thing became clear to me this summer: water cannot be stopped by "pseudo-measures." Therefore, I see only the elevation level as a decisive factor. (P.S.: There are still house owners on the Elbe who do nothing during floods except leave the doors open at the front and back on the ground floor: the water flows in through the front and out the back. Then all you can do is wait until it recedes. Whether you want to live with that is up to you. But I will NEVER again make statements about flooding being "very unlikely.")
Bookstar schrieb:
I would completely ignore it; a dam does not break.
When exactly that happened, it was the end of a residential area that was never rebuilt. I cannot draw conclusions about this from a construction engineering perspective, as I am not an expert. But one thing became clear to me this summer: water cannot be stopped by "pseudo-measures." Therefore, I see only the elevation level as a decisive factor. (P.S.: There are still house owners on the Elbe who do nothing during floods except leave the doors open at the front and back on the ground floor: the water flows in through the front and out the back. Then all you can do is wait until it recedes. Whether you want to live with that is up to you. But I will NEVER again make statements about flooding being "very unlikely.")
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