ᐅ Constructing a Cost-Effective Retaining Wall / Slope Stabilization
Created on: 27 Feb 2019 13:50
A
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.
sichtbeton82 schrieb:
Alternatively, you can also install gabions. They are generally quite affordable. The cost is mainly determined by the infill material. If you can source inexpensive infill, for example, your own stony excavation from another location or good prices at the local quarry, it can be cost-effective.
Additional advantages: shelter for many animal species. No issues with water pressure. Gabions at this height need to be at least 50-80 cm (20-32 inches) wide. Filling them with stones is also very expensive.
Just think about it for a moment...
A 45m (147 ft) wall, let's say it’s 2m (6.5 ft) high everywhere, that’s a total of 90m² (970 ft²) of wall surface. With 30cm (12 inches) formwork blocks, you have a concrete volume of about 210 liters (55.5 gallons) per m², which equals roughly 18,900 liters (5,000 gallons). Let’s round that to 19m³ (670 cubic feet). At a weight of 2.5 tons (2.5 short tons) per cubic meter of concrete, that’s about 47.5 tons (52.4 short tons) of concrete—mind you, not counting the foundation. The material first has to be transported to the site, loaded into the mixer, and then poured into the formwork blocks.
You definitely need to be in good shape!
But let’s start even earlier. One formwork block weighs about 23 kg (51 lbs), and you need 8 pieces per m² of wall surface, so a total of 720 blocks. Just carrying those to the rear alone means moving about 16.5 tons (18.2 short tons) of material.
It’s all doable, but be aware that your concrete mixer will be running for a long time, you’ll sweat a lot, and if you don’t lift loads in a back-friendly way, your back might give out before you finish building the wall.
Think about it! Saving money is good, but a wall like this doesn’t come cheap, even if you do everything yourself.
A 45m (147 ft) wall, let's say it’s 2m (6.5 ft) high everywhere, that’s a total of 90m² (970 ft²) of wall surface. With 30cm (12 inches) formwork blocks, you have a concrete volume of about 210 liters (55.5 gallons) per m², which equals roughly 18,900 liters (5,000 gallons). Let’s round that to 19m³ (670 cubic feet). At a weight of 2.5 tons (2.5 short tons) per cubic meter of concrete, that’s about 47.5 tons (52.4 short tons) of concrete—mind you, not counting the foundation. The material first has to be transported to the site, loaded into the mixer, and then poured into the formwork blocks.
You definitely need to be in good shape!
But let’s start even earlier. One formwork block weighs about 23 kg (51 lbs), and you need 8 pieces per m² of wall surface, so a total of 720 blocks. Just carrying those to the rear alone means moving about 16.5 tons (18.2 short tons) of material.
It’s all doable, but be aware that your concrete mixer will be running for a long time, you’ll sweat a lot, and if you don’t lift loads in a back-friendly way, your back might give out before you finish building the wall.
Think about it! Saving money is good, but a wall like this doesn’t come cheap, even if you do everything yourself.
I would think this through carefully, honestly.
We built a terrace about 17m (55.8 ft) long with a height of 75cm (30 inches). Just carrying the stones, about 15 to 20 at a time, was really tough.
It was doable, and after working hard for one weekend it was finished, but it was definitely exhausting.
We picked up the cement bags with a trailer – we had a mixer – and also got the gravel (or whatever the material is called) directly from the gravel supplier using the trailer.
You have to remember that you’re moving tons of material, and we only built a small wall.
So if you’re fit and motivated, go for it; if not, look for alternatives.
We built a terrace about 17m (55.8 ft) long with a height of 75cm (30 inches). Just carrying the stones, about 15 to 20 at a time, was really tough.
It was doable, and after working hard for one weekend it was finished, but it was definitely exhausting.
We picked up the cement bags with a trailer – we had a mixer – and also got the gravel (or whatever the material is called) directly from the gravel supplier using the trailer.
You have to remember that you’re moving tons of material, and we only built a small wall.
So if you’re fit and motivated, go for it; if not, look for alternatives.
I have the impression that you want to build a vertical retaining wall, with a sloped embankment continuing above it; and that you intend to stabilize this wall only with a foundation and reinforcement, without anchoring it into the hillside.
If that is indeed your plan, it sounds to me like a questionable approach with little regard for physics — also, the question of how steep a slope can be without significant risk of slipping depends greatly on the soil quality, and unfortunately also on its current moisture content and frost penetration.
I would incline the retaining wall into the hillside and anchor it there, and also design a gentler transition where the slope above begins. With experience, this can also be done using concrete formwork blocks, but I would personally prefer to use planter rings.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
If that is indeed your plan, it sounds to me like a questionable approach with little regard for physics — also, the question of how steep a slope can be without significant risk of slipping depends greatly on the soil quality, and unfortunately also on its current moisture content and frost penetration.
I would incline the retaining wall into the hillside and anchor it there, and also design a gentler transition where the slope above begins. With experience, this can also be done using concrete formwork blocks, but I would personally prefer to use planter rings.
Webmaster-uk schrieb:Poor kids :-(
Since I can’t see the wall and the neighbor is a daycare, I wouldn’t care much about the appearance
hstkai schrieb:I am always surprised how many people don’t realize that search result rankings are personalized and cached for each user. I assume in this case we have the same third result (Jasto), but it could vary. My first result currently is Zieglowski (Pellenz is just across from here, and I rarely clear caches).
Try googling "concrete formwork block instructions," the PDF in the third link should be interesting for you.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
H
HilfeHilfe28 Feb 2019 17:05Hello, I built it with my buddy in about 3 or 4 days. We mixed the concrete ourselves and carefully poured it. We had the materials delivered from a wholesaler and borrowed a mixer from my brother-in-law. Sometimes there are mixers available for rent at a discount. The problem with ready-mixed concrete delivery is, first, the area is small, and second, they usually add an additive so it doesn’t harden for several hours after unloading. Then you need a bunch of people to pour it into the blocks. Using a mixer is the least stressful and cleaner solution. It’s also more cost-effective.
Winniefred28 Feb 2019 17:54We are facing a similar problem. Our wall is about 50m (165 feet) long, and roughly the last 15-20m (50-65 feet) need repairs. Since the land slopes slightly, the wall is 1.2m (4 feet) high at the highest point and gradually gets lower towards the front. Behind it, there are old privet hedges and shrubs everywhere (public land, with a sidewalk next to it).
So far, I haven’t found any practical and affordable solutions. I have come to accept that one day we will simply have to invest a significant amount of money and hire a large construction company for the job. The wall is 100 years old and leans inward slightly over about 8m (26 feet), plaster is falling off all over, and it won’t hold up for much longer. Since our backyard is quite narrow, I gave up on the idea of creating a slope or embankment. That would take up too much of our property. Plus, whatever was there before would also have to be supported. You can’t just tear down the old wall like that… at least in our case, we would face a lot of obstacles.
We also have the issue that cars cannot access the site, at least not larger vehicles. Considering how many tons of materials would be needed, it’s almost crazy to try to do it ourselves. You need real manpower and machinery.
To make things more complicated, there is a streetlight, so first we need to get the underground electrical plans from the civil engineering department.
Honestly, these projects are really no fun, neither financially nor in terms of effort.
So far, I haven’t found any practical and affordable solutions. I have come to accept that one day we will simply have to invest a significant amount of money and hire a large construction company for the job. The wall is 100 years old and leans inward slightly over about 8m (26 feet), plaster is falling off all over, and it won’t hold up for much longer. Since our backyard is quite narrow, I gave up on the idea of creating a slope or embankment. That would take up too much of our property. Plus, whatever was there before would also have to be supported. You can’t just tear down the old wall like that… at least in our case, we would face a lot of obstacles.
We also have the issue that cars cannot access the site, at least not larger vehicles. Considering how many tons of materials would be needed, it’s almost crazy to try to do it ourselves. You need real manpower and machinery.
To make things more complicated, there is a streetlight, so first we need to get the underground electrical plans from the civil engineering department.
Honestly, these projects are really no fun, neither financially nor in terms of effort.
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