ᐅ Foundation for a 1.5-meter-high retaining wall made of large rectangular blocks.
Created on: 9 Mar 2019 07:40
T
Thierse
A retaining wall 1.5 meters high (5 feet) is to be built using large ashlar stones (shell limestone). What should the foundation look like in terms of depth and material?
These stones are very heavy; is a special foundation necessary, or would, for example, a 30 cm (12 inches) layer of crushed stone beneath be sufficient?
And is drainage required? Or is a layer of crushed stone behind the retaining wall enough?
These stones are very heavy; is a special foundation necessary, or would, for example, a 30 cm (12 inches) layer of crushed stone beneath be sufficient?
And is drainage required? Or is a layer of crushed stone behind the retaining wall enough?
Hello KingSong,
3° slope towards the house. The bird has a sense of humor. What is that supposed to achieve?
You’re going to excavate the foundation anyway. Just put around 20 cm (8 inches) of RCL (road construction layer) in as a base. That should be more than enough to prevent capillary rise. Then add 40 cm (16 inches) of concrete. Whether you mix lean concrete (1:5) or regular concrete (1:3) shouldn’t make a big difference. Saving 200 euros on cement for a project like this is not worth it.
I also had to create a foundation here. About 22 meters (72 feet) long, 90 cm (35 inches) deep (I’m just a safety enthusiast). The estimate was 12,500 euros. I did it myself (including someone who could operate a mini excavator). It cost me around 3,500 euros in total. And it will hold until the next Stone Age.
Steven
3° slope towards the house. The bird has a sense of humor. What is that supposed to achieve?
You’re going to excavate the foundation anyway. Just put around 20 cm (8 inches) of RCL (road construction layer) in as a base. That should be more than enough to prevent capillary rise. Then add 40 cm (16 inches) of concrete. Whether you mix lean concrete (1:5) or regular concrete (1:3) shouldn’t make a big difference. Saving 200 euros on cement for a project like this is not worth it.
I also had to create a foundation here. About 22 meters (72 feet) long, 90 cm (35 inches) deep (I’m just a safety enthusiast). The estimate was 12,500 euros. I did it myself (including someone who could operate a mini excavator). It cost me around 3,500 euros in total. And it will hold until the next Stone Age.
Steven
The idea was considered, but the entire house is on a slope. At the entrance door of the extension (still visible in the photo), we are only about 1m (3.3 feet) above ground level, and the rest of the house is even built 40cm (16 inches) into the terrain. A basement with a floor area of 200m² (2,150 sq ft) would have been completely disproportionate, and we really don’t need a basement.
H
hampshire17 Mar 2019 23:34With all the considerations about the foundation: don’t forget the drainage...
KingSong schrieb:
This slope needs to be retained:
Part of the house is built on it (with a total of 2.40m (8 feet) of frost protection gravel, laid 80cm (31.5 inches) deep), and we simply don’t like concrete formwork blocks. I also don’t think those formwork blocks can withstand this pressure in the long term. For us, concrete blocks have a certain aesthetic that fits well with the rest of the house. On the left side (where the pavement is now), a carport will be built, which will then be supported on the blocks above.
The blocks aren’t that expensive either—a 180cm x 60cm x 60cm (71 inches x 24 inches x 24 inches) block costs me €75, and altogether we would be at about €3,400 gross including delivery. Hello @KingSong, your house is built quite a bit higher. How did you fill under your house or what type of foundation is underneath? Could you also share some information about the foundation costs? Thanks in advance.
The foundation for the house is made exclusively of frost protection gravel, compacted in layers. The minimum depth below the original ground level is 1 meter (3.3 feet); due to the slope, at the deepest point we are about 2.40 meters (7.9 feet) deep. The entire earthworks, including drainage and everything involved, cost us €24,000.
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