ᐅ Plot with a change in ground level – boundary wall between neighbors – foundation?
Created on: 10 Jul 2017 19:20
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DReffects
Hello!
I hope this is roughly the correct section for my question; if not, please feel free to move it.
Situation:
The neighbor’s plot is significantly higher than mine, and their garage was built just 20cm (8 inches) from the property line. Since the development plan actually requires that there be no sudden changes in ground level, the neighbor should have compensated for the height difference with a slope at about 45°. My garden level means there would be a roughly 1.5m (5 feet) wide slope here—of course, at the expense of their plot. So, we agreed that instead of the slope (and demolishing part of the garage...), the neighbor must build a retaining wall on the property line, which also ensures that drainage happens where it’s supposed to.
We have not yet set the final ground level on our side; we plan to lower it by about 70cm (28 inches). Now, the neighbor has dug a trench along the property line, poured concrete into it, and is building a wall on this foundation using hollow blocks that they also plan to fill with concrete later.
If I remove about 70cm (28 inches) of soil on my side, this will expose all but 30cm (12 inches) of their foundation. From my point of view, 30cm (12 inches) is not enough to support a roughly 1.8m (6 feet) high wall along with the adjacent garage and garden.
The neighbor disagrees. Therefore, my question: is there an online calculator somewhere that can determine the required foundation depth? I would rather not have the neighbor’s wall collapse on my children in a year... My construction company has also expressed concerns and does not want to carry out any further earthworks until the wall issue is resolved.
Thank you
I hope this is roughly the correct section for my question; if not, please feel free to move it.
Situation:
The neighbor’s plot is significantly higher than mine, and their garage was built just 20cm (8 inches) from the property line. Since the development plan actually requires that there be no sudden changes in ground level, the neighbor should have compensated for the height difference with a slope at about 45°. My garden level means there would be a roughly 1.5m (5 feet) wide slope here—of course, at the expense of their plot. So, we agreed that instead of the slope (and demolishing part of the garage...), the neighbor must build a retaining wall on the property line, which also ensures that drainage happens where it’s supposed to.
We have not yet set the final ground level on our side; we plan to lower it by about 70cm (28 inches). Now, the neighbor has dug a trench along the property line, poured concrete into it, and is building a wall on this foundation using hollow blocks that they also plan to fill with concrete later.
If I remove about 70cm (28 inches) of soil on my side, this will expose all but 30cm (12 inches) of their foundation. From my point of view, 30cm (12 inches) is not enough to support a roughly 1.8m (6 feet) high wall along with the adjacent garage and garden.
The neighbor disagrees. Therefore, my question: is there an online calculator somewhere that can determine the required foundation depth? I would rather not have the neighbor’s wall collapse on my children in a year... My construction company has also expressed concerns and does not want to carry out any further earthworks until the wall issue is resolved.
Thank you
Nordlys schrieb:
So, what he’s building there looks like an anchor. In the ground. Just think about it..... That’s exactly the point I don’t understand. It was explained to me that the soil constantly pushes from right to left. So I would have to brace myself on the left side at the base to counteract the pressure from right to left. What’s the point of connecting more firmly to the part of the soil that is pushing to the left?
From what I was told, I perceive the anchors on his side like someone trying to stop a rolling car by lying on the windshield instead of placing a wheel chock in front of the tires.
DReffects schrieb:
Uh, don’t get me wrong – but these L-shaped blocks are on his side. How are they supposed to resist the earth pressure pushing towards me? Or am I misunderstanding something? The L should be on the side where the pressure is, so on his side.
DReffects schrieb:
However, due to the roughly 45° angle of the terrain pressure, the L-section would have to be below our lawn to be effective as a support here. No, that would be the wrong reference point. It already looks correct as it is.
DReffects schrieb:
How should this be assessed in terms of frost protection and drainage? As for whether any particular type of drainage is necessary here, I’ll keep quiet since I don’t really know. I already suggested a backfill with an insulation layer on your side of the wall.
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DReffects schrieb:
This is exactly the point I don’t understand. I was told that the ground constantly pushes from right to left. So I would have to brace myself on the left side at the base to resist the pressure from right to left. There could be a causal link between not understanding and a flawed explanation.
The L-shaped retaining wall works through the rigidity of the angle in the L. The load from above on the horizontal leg acts (similar to water displacement on a ship) in such a way that it can practically be subtracted from the pressure on the horizontal leg. Its long (and stepped) extensions achieve this effect even better than the “ready-made” L-shaped retaining wall model.
Translated to your picture: the L applies axle load / bearing pressure on the braked axle.
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11ant schrieb:
The L should be placed on the active (pressure) side, so on its side.
No, that would be the wrong reference point. It already looks correct as it is.11ant schrieb:
There might be a causal connection between not understanding and a silly explanation.
The L-block works through the stiffness of the angle in the L shape. The load from above on the horizontal leg acts (similar to water displacement on a ship) in a way that you can practically subtract it from the pressure on the horizontal leg. Its long (and stepped) projections actually achieve this better than the ready-made L-block model.
Translated to your picture: the L applies axle load / clamping pressure on the braked axle.Okay, interesting! Thanks for the information. I understand almost nothing of it, but at least it sounds better than before.
Do you mean that the higher density of the wall with its cantilevers (its “weight”) increases the downward pressure so much that the moving soil presses tightly against the fixed part of the ground and becomes stable?
I was explained differently by the construction manager and a supervising engineer. They sketched the following drawing for me:
However, it’s also quite possible that I simply didn’t get it. My field of expertise is quite different... Of course, I would prefer if their explanation is correct. The visual aspect can be changed anyway. My builder only told me that they won’t get closer than about 1 meter (3 feet) to the wall with earthworks because they’re afraid the whole thing might collapse.
That was before the anchors were installed. On Tuesday there’s an inspection with the construction manager!
DReffects schrieb:
Do you mean that the greater density of the wall with its cantilevers (its "weight") increases the downward pressure so much that the moving soil presses against the fixed part of the ground and gets stuck? No. I mean that gravity also acts on the neighbor’s soil. It will never move solely onto your property but always downwards as well. In doing so, it presses on the horizontal leg of the L-shape (or the cantilevers here). The connection between that and the horizontal leg, in turn, reinforces it and “holds” it.
DReffects schrieb:
The construction manager and a site engineer explained it to me differently. The engineer made this sketch: I’m familiar with the phenomenon that, in physics, the opposite is often the first (and sometimes much stronger) impression – I experience that myself too. The engineer’s explanation is what you might call “pseudo-logical.” In reality, in such a setup, the horizontal leg of the L-shape is only loaded from the weaker side, which is less than equivalent and does not contribute to a “win.” The L-shaped blocks would be pushed at an angle and upwards.
But that’s the beauty of physics: it works reliably even if you don’t understand it (and it doesn’t have to wait to be understood). It acts immediately.
DReffects schrieb:
My building company just told me they will not carry out any earthworks closer than one meter from the wall because they fear it might collapse I’m not worried about the part of the wall with the garden. For the section of the wall supporting the garage above, I might expect several centimeters of tilt per decade—and that only if the adjacent ground starts to shift. As long as heavy rain doesn’t undermine the garage, I don’t see this happening. No guarantees, of course, but also no cause for concern.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
I wouldn’t worry about it. In the first picture, the support on your side of the wall is clearly visible. However, I would still label the board as "load-bearing."
SCNR
If you’re still unsure about the L-block principle, look into how wave breakers work at concerts. It’s the same concept.
SCNR
If you’re still unsure about the L-block principle, look into how wave breakers work at concerts. It’s the same concept.
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