Hello everyone,
We are currently looking at a plot of land and still have some concerns regarding the existing slope on the site. It concerns plots No. 5 and 6 – we would take plot 5 entirely and about up to the turning circle on plot 6. So, we can still combine parts of these plots. In total, that would be around 1100 square meters (11,840 square feet). Behind the plot, at a lower level, there is the RRB on the right, and oaks are planned to be planted there. The elevations are also shown here.
Looking at the heights, I currently have quite a few worries and am not sure if this is really the right plot for our building project.
The plan is for approximately 200 square meters (2,150 square feet) of living space in a staggered storey design, with a double garage next to it. We will need to compensate for about 1.5 meters (5 feet) of height difference along the length of the building.
The groundwater level is at about -1.2 meters (-4 feet). The entire lower area behind the plot was underwater for quite some time during this past winter, in which there was significant rainfall here in Schleswig-Holstein. Whether the water reached up to the plot itself, I cannot say for sure as I was not on site at the time.
From my perspective, I see three immediate issues:
1) Water coming "downhill" from above, i.e., from plots 3 and 4, which are also at least about 2 meters (6.5 feet) higher than us. A friend of mine says that a splash guard in the form of a small wall at the property boundary would be sufficient – a 40 to 50 cm (16 to 20 inch) high small wall would redirect storm runoff during extreme heavy rain events around the plot and house. Do you think this would be enough, or is that too naive?
2) In the same town this year, there was a case where a house without a basement apparently had some interior rooms become damp due to the high groundwater, because the foundation was sitting in the groundwater and water was drawn up through the floor slab into the house. Until now, I only knew of this kind of issue with basements. The architect mentioned drainage that could divert the water to lower areas, but my specific question here is: what if the lower area can no longer absorb any more water? Wouldn’t the drainage then be ineffective? Alternatively, the foundations or the slab could be constructed using waterproof concrete (WU concrete), but that would considerably increase costs.
I’m an amateur, so sorry for the question – how would you approach these height and location issues?
And finally:
3) Is it possible that, with increasing rainfall amounts, parts of the plot could remain permanently flooded? I have pictures in my mind of flooding along rivers where whole meadows get submerged and stay underwater for weeks. That, of course, would not be desirable. Logically, I think the entire lower area is quite large and lies about 2 meters (6.5 feet) below our plot – there should be enough space there, and if those 2 meters were completely underwater, that would mean billions of liters of water.
A soil survey specifically for the plot is still planned, but a report from the road construction company has already been done, which I will also attach here. According to the architect, the soil condition does not appear to be very problematic.
How would you handle the location of a plot like this? Do you see any further problems that I might have overlooked?
Am I being too cautious? I have a basement that was waterproofed with a "black tank" (a type of waterproofing membrane) in 1998. It has never really caused serious problems, but it basically sits in groundwater, and I have to pump water out of a sump all day, because back then no one told us about "white tanks" (concrete waterproofing). Those are mistakes you simply can’t fix later, and I want to avoid something similar with what will likely be the last house I ever build.
Looking forward to your suggestions, assessments, and opinions.
Best regards
P.S.: I know that compared to other federal states this is probably not an extreme slope, but rather a plot with a relatively steep incline. However, considering climate change, I am already giving it quite a lot of thought today.
We are currently looking at a plot of land and still have some concerns regarding the existing slope on the site. It concerns plots No. 5 and 6 – we would take plot 5 entirely and about up to the turning circle on plot 6. So, we can still combine parts of these plots. In total, that would be around 1100 square meters (11,840 square feet). Behind the plot, at a lower level, there is the RRB on the right, and oaks are planned to be planted there. The elevations are also shown here.
Looking at the heights, I currently have quite a few worries and am not sure if this is really the right plot for our building project.
The plan is for approximately 200 square meters (2,150 square feet) of living space in a staggered storey design, with a double garage next to it. We will need to compensate for about 1.5 meters (5 feet) of height difference along the length of the building.
The groundwater level is at about -1.2 meters (-4 feet). The entire lower area behind the plot was underwater for quite some time during this past winter, in which there was significant rainfall here in Schleswig-Holstein. Whether the water reached up to the plot itself, I cannot say for sure as I was not on site at the time.
From my perspective, I see three immediate issues:
1) Water coming "downhill" from above, i.e., from plots 3 and 4, which are also at least about 2 meters (6.5 feet) higher than us. A friend of mine says that a splash guard in the form of a small wall at the property boundary would be sufficient – a 40 to 50 cm (16 to 20 inch) high small wall would redirect storm runoff during extreme heavy rain events around the plot and house. Do you think this would be enough, or is that too naive?
2) In the same town this year, there was a case where a house without a basement apparently had some interior rooms become damp due to the high groundwater, because the foundation was sitting in the groundwater and water was drawn up through the floor slab into the house. Until now, I only knew of this kind of issue with basements. The architect mentioned drainage that could divert the water to lower areas, but my specific question here is: what if the lower area can no longer absorb any more water? Wouldn’t the drainage then be ineffective? Alternatively, the foundations or the slab could be constructed using waterproof concrete (WU concrete), but that would considerably increase costs.
I’m an amateur, so sorry for the question – how would you approach these height and location issues?
And finally:
3) Is it possible that, with increasing rainfall amounts, parts of the plot could remain permanently flooded? I have pictures in my mind of flooding along rivers where whole meadows get submerged and stay underwater for weeks. That, of course, would not be desirable. Logically, I think the entire lower area is quite large and lies about 2 meters (6.5 feet) below our plot – there should be enough space there, and if those 2 meters were completely underwater, that would mean billions of liters of water.
A soil survey specifically for the plot is still planned, but a report from the road construction company has already been done, which I will also attach here. According to the architect, the soil condition does not appear to be very problematic.
How would you handle the location of a plot like this? Do you see any further problems that I might have overlooked?
Am I being too cautious? I have a basement that was waterproofed with a "black tank" (a type of waterproofing membrane) in 1998. It has never really caused serious problems, but it basically sits in groundwater, and I have to pump water out of a sump all day, because back then no one told us about "white tanks" (concrete waterproofing). Those are mistakes you simply can’t fix later, and I want to avoid something similar with what will likely be the last house I ever build.
Looking forward to your suggestions, assessments, and opinions.
Best regards
P.S.: I know that compared to other federal states this is probably not an extreme slope, but rather a plot with a relatively steep incline. However, considering climate change, I am already giving it quite a lot of thought today.
H
hanghaus202331 May 2024 09:43With good planning, your desired plot of land can also be made usable. It seems the budget is not an issue.
H
hanghaus202331 May 2024 10:03You have about a 7% slope towards the west. No water will come onto your property from the street, and on the east side there will be a lawn edging; so nothing will flow onto your property from there either. Build the house as high as possible to be on the safe side.
If there is a low spot, just fill it in.
If there is a low spot, just fill it in.