Hello,
we want to fully support the slope on our hillside property (sloping down away from the street) from the front corner of the house to the side property line, in order to create a level parking space at the top near the street and to have a slightly flat area at the bottom.
A full story height needs to be retained, so about 3 meters (10 feet) high. The width up to the side boundary is approximately 3.50 meters (11.5 feet).
Now the question arises what options we have. So far, I have come up with the following three possibilities:
A) The most obvious solution would be to install L-shaped retaining wall blocks. The problem is first finding someone willing to do this (few but very large blocks), as well as the cost and appearance.
B) The currently most likely approach is to build a wall from concrete formwork blocks together with my father. Based on statics found online, I would choose 24 cm (9.5 inches) blocks and construct it with appropriate reinforcement (vertical and horizontal) on a frost-protected concrete foundation. Ideally, I would then have it plastered directly with the house. The advantages would be appearance and cost. However, I am uncertain whether this wall (retaining soil on one side plus traffic load from the parking space) will really hold up over time. Are these concerns justified?
C) A completely new idea I had is gabion walls, since these are apparently designed to handle high loads if built with sufficient width and can be constructed relatively tall.
What is your opinion? What is ultimately the best option for such a high wall that also needs to bear significant loads? Possibly any other suggestions?
we want to fully support the slope on our hillside property (sloping down away from the street) from the front corner of the house to the side property line, in order to create a level parking space at the top near the street and to have a slightly flat area at the bottom.
A full story height needs to be retained, so about 3 meters (10 feet) high. The width up to the side boundary is approximately 3.50 meters (11.5 feet).
Now the question arises what options we have. So far, I have come up with the following three possibilities:
A) The most obvious solution would be to install L-shaped retaining wall blocks. The problem is first finding someone willing to do this (few but very large blocks), as well as the cost and appearance.
B) The currently most likely approach is to build a wall from concrete formwork blocks together with my father. Based on statics found online, I would choose 24 cm (9.5 inches) blocks and construct it with appropriate reinforcement (vertical and horizontal) on a frost-protected concrete foundation. Ideally, I would then have it plastered directly with the house. The advantages would be appearance and cost. However, I am uncertain whether this wall (retaining soil on one side plus traffic load from the parking space) will really hold up over time. Are these concerns justified?
C) A completely new idea I had is gabion walls, since these are apparently designed to handle high loads if built with sufficient width and can be constructed relatively tall.
What is your opinion? What is ultimately the best option for such a high wall that also needs to bear significant loads? Possibly any other suggestions?
Hello Paminke,
24cm (10 inches) formwork blocks are too thin for my taste. Keep in mind that the outer shell is only the formwork for the concrete.
I would not use formwork blocks but instead fully form the retaining wall.
However, I don’t think the durability of the retaining wall is your biggest concern. The foundation is more important. You want to build a 3-meter (10 feet) high wall that has to withstand a lot of pressure on the ground? Even with L-shaped blocks, I wouldn’t take that risk without a structural engineer. And relying on “structural calculations found on the internet” is, in my opinion, not a good approach. If the wall falls and some people get hurt, telling the judge about the “structural calculations found on the internet” will probably make things worse legally.
My advice: don’t take this risk.
Steven
24cm (10 inches) formwork blocks are too thin for my taste. Keep in mind that the outer shell is only the formwork for the concrete.
I would not use formwork blocks but instead fully form the retaining wall.
However, I don’t think the durability of the retaining wall is your biggest concern. The foundation is more important. You want to build a 3-meter (10 feet) high wall that has to withstand a lot of pressure on the ground? Even with L-shaped blocks, I wouldn’t take that risk without a structural engineer. And relying on “structural calculations found on the internet” is, in my opinion, not a good approach. If the wall falls and some people get hurt, telling the judge about the “structural calculations found on the internet” will probably make things worse legally.
My advice: don’t take this risk.
Steven
Don’t you have to get approval for that anyway?
As an alternative to L-shaped concrete blocks, you can use hollow concrete walls for such heights, which are then filled with concrete. Depending on the height or the length, this can be more cost-effective.
I agree with the previous comments. Without structural engineering calculations, you can’t do anything!
The foundation also has to be suitable for the L-shaped blocks. Supporting a 3-meter (10-foot) height is not a trivial task...
As an alternative to L-shaped concrete blocks, you can use hollow concrete walls for such heights, which are then filled with concrete. Depending on the height or the length, this can be more cost-effective.
I agree with the previous comments. Without structural engineering calculations, you can’t do anything!
The foundation also has to be suitable for the L-shaped blocks. Supporting a 3-meter (10-foot) height is not a trivial task...
Our structural engineer calculated the reinforcement and designed the concrete wall so robustly that the construction company questioned whether the plans were correct.
If the wall fails, you are held liable. Even L-shaped retaining blocks are not a cure-all without a proper foundation. Structural calculations are required anyway, so the wall design can be included at the same time.
If the wall fails, you are held liable. Even L-shaped retaining blocks are not a cure-all without a proper foundation. Structural calculations are required anyway, so the wall design can be included at the same time.
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