ᐅ Constructing a Cost-Effective Retaining Wall / Slope Stabilization
Created on: 27 Feb 2019 13:50
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abc12345
Hello everyone,
The weather is steadily improving, so it’s time to start planning the outdoor area. Parts of the property will need to be filled in. The site has already been surveyed, and leveling at the lowest point would require approximately 2 meters (6.5 feet) of fill soil.
There are gardens adjacent to the property on all sides, so I will need to build a retaining wall accordingly.
I have already spoken with the local building materials supplier. He suggested simply making a foundation by excavating 1 meter (3.3 feet) deep, then adding a 20 cm (8 inches) layer of crushed stone, followed by 80 cm (31.5 inches) of reinforced concrete. On top, concrete blocks would be placed, reinforced with rebar and filled with concrete. He recommended using blocks sized 26 cm or 29 cm (10 or 11.5 inches), but said he could not provide structural calculations or any official advice. He quoted me a material cost of about 3,500 euros.
Nothing was mentioned about installing drainage. I’m also unsure where the water would be directed since all sides border neighboring properties. Or did I misunderstand the purpose of drainage—is it to carry water away from the retaining wall to somewhere else?
Now my question is whether there might be other, possibly more cost-effective ways to do this? Precast L-shaped concrete elements are available here, but they cost about three times as much and require a mini-excavator for installation.
Another option I considered is to reduce the wall height to 1 meter (3.3 feet) and create a steep slope up to the fill level. However, I’m not sure how steep the slope can be without causing sliding. The property will later be enclosed with a dense hedge for privacy. As far as I understand, the wall must be set back 2 meters (6.5 feet) from the property boundary to avoid problems with height restrictions, especially because the ground has already been raised by 2 meters (6.5 feet).
I want to minimize the amount of space lost to make the most of the property, but I also want to keep costs relatively low since there are many other projects planned.
Since I can’t see the wall from my side and the neighbor is a daycare center, appearance is not a major concern for me.
Maybe you have some ideas or tips on the best way to approach this.
Thank you in advance for your help.
The weather is steadily improving, so it’s time to start planning the outdoor area. Parts of the property will need to be filled in. The site has already been surveyed, and leveling at the lowest point would require approximately 2 meters (6.5 feet) of fill soil.
There are gardens adjacent to the property on all sides, so I will need to build a retaining wall accordingly.
I have already spoken with the local building materials supplier. He suggested simply making a foundation by excavating 1 meter (3.3 feet) deep, then adding a 20 cm (8 inches) layer of crushed stone, followed by 80 cm (31.5 inches) of reinforced concrete. On top, concrete blocks would be placed, reinforced with rebar and filled with concrete. He recommended using blocks sized 26 cm or 29 cm (10 or 11.5 inches), but said he could not provide structural calculations or any official advice. He quoted me a material cost of about 3,500 euros.
Nothing was mentioned about installing drainage. I’m also unsure where the water would be directed since all sides border neighboring properties. Or did I misunderstand the purpose of drainage—is it to carry water away from the retaining wall to somewhere else?
Now my question is whether there might be other, possibly more cost-effective ways to do this? Precast L-shaped concrete elements are available here, but they cost about three times as much and require a mini-excavator for installation.
Another option I considered is to reduce the wall height to 1 meter (3.3 feet) and create a steep slope up to the fill level. However, I’m not sure how steep the slope can be without causing sliding. The property will later be enclosed with a dense hedge for privacy. As far as I understand, the wall must be set back 2 meters (6.5 feet) from the property boundary to avoid problems with height restrictions, especially because the ground has already been raised by 2 meters (6.5 feet).
I want to minimize the amount of space lost to make the most of the property, but I also want to keep costs relatively low since there are many other projects planned.
Since I can’t see the wall from my side and the neighbor is a daycare center, appearance is not a major concern for me.
Maybe you have some ideas or tips on the best way to approach this.
Thank you in advance for your help.
Winniefred8 Mar 2019 18:00If you want a wall, I would probably prefer a smaller wall combined with a reinforced slope. This will likely make the property blend more harmoniously and also allows for insect-friendly planting, which usually looks better visually. However, I’m not sure if it’s possible to achieve this with these dimensions without losing much usable land. A height of 80cm (31 inches) is quite significant if the slope is going to be fairly steep.
So, I think the decision is made.
I will build the wall halfway up and then cover the difference with a planted slope.
Now I have the following question regarding the concrete formwork blocks:
Should I use the 17.5cm (7 inches) concrete formwork blocks and reinforce them to a height of 1.35 meters (4 ft 5 in), or go with the 36.5cm (14 inches) blocks and build them to 1.30 meters (4 ft 3 in) without reinforcement? The 17.5cm (7 inches) blocks will cost me about 22 euros per m² (square meter), and the 36.5cm (14 inches) blocks about 36 euros per m². The foundation area would be 40 m², so approximately 880 euros for the 17.5cm (7 inches) blocks and 1,440 euros for the 36.5cm (14 inches) blocks.
That’s a difference of roughly 440 euros.
EDIT:
The concrete volume per block for the 17.5cm (7 inches) blocks would be about 0.11 m³ (3.9 cubic feet), and for the 36.5cm (14 inches) blocks about 0.24 m³ (8.5 cubic feet).
Now the question is how the calculation works out with reinforcement and the required amount of concrete. I’m not sure where the price would end up.
What do you think is the better option, also considering the labor involved in installing the reinforcement as well as the workload due to heavier blocks and the larger volume of concrete needed?
I will build the wall halfway up and then cover the difference with a planted slope.
Now I have the following question regarding the concrete formwork blocks:
Should I use the 17.5cm (7 inches) concrete formwork blocks and reinforce them to a height of 1.35 meters (4 ft 5 in), or go with the 36.5cm (14 inches) blocks and build them to 1.30 meters (4 ft 3 in) without reinforcement? The 17.5cm (7 inches) blocks will cost me about 22 euros per m² (square meter), and the 36.5cm (14 inches) blocks about 36 euros per m². The foundation area would be 40 m², so approximately 880 euros for the 17.5cm (7 inches) blocks and 1,440 euros for the 36.5cm (14 inches) blocks.
That’s a difference of roughly 440 euros.
EDIT:
The concrete volume per block for the 17.5cm (7 inches) blocks would be about 0.11 m³ (3.9 cubic feet), and for the 36.5cm (14 inches) blocks about 0.24 m³ (8.5 cubic feet).
Now the question is how the calculation works out with reinforcement and the required amount of concrete. I’m not sure where the price would end up.
What do you think is the better option, also considering the labor involved in installing the reinforcement as well as the workload due to heavier blocks and the larger volume of concrete needed?
Keep in mind that the manuals probably assume you have at least some free working space on the side without backfilling.
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HilfeHilfe9 Mar 2019 13:45The amount of concrete you need will be calculated by your building materials supplier. They would usually add a few steel bars in there. I would have built it up higher to provide a sufficient surface area.
11ant schrieb:
Keep in mind that the instructions probably assume you have at least some free working space on the side without backfill.It shouldn’t be an issue to use the neighboring property as a work area.
HilfeHilfe schrieb:
Your building materials supplier can calculate how much concrete you’ll need. For steel reinforcement, they’d usually add a few bars here and there. I would have built it up higher so you get a level surface.So you mean it’s possible to fill at ground level without having a slope?
I’m just unsure about this. I’ve recently talked to two other people independently, and both said that if you don’t build a wall and have a 60-degree slope that only takes up 60cm (24 inches) of your property, you should consider whether it’s worth it. Since I want to plant a privacy hedge anyway, and that needs to be set back some distance from the boundary so I can easily trim it from behind.
I would definitely need to replace the existing fence with something more substantial. If I look up, for example, steel mesh fencing, it would cost about the same as a wall. The cheapest option would be wooden privacy panels just to mark the boundary.
Putting aside everything that’s been said so far…
How would you decide if it were your property and you had to make this decision? The only thing that definitely needs to be done is leveling the plot and removing the fir trees.
I’m a bit at a loss :-(
H
HilfeHilfe9 Mar 2019 18:37Well, how would I decide? If I still had 500 square meters (5400 square feet) of land, I wouldn’t care about the slope… and it would be stress-free. But if you only have 150 square meters (1600 square feet) of lawn left, every bit of extra space is welcome! That’s how it was for us! Everything was properly balanced! And it’s also easier when mowing.
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