ᐅ Use L-shaped retaining blocks for slope stabilization.

@Patchwork: About 10,000 €. This also includes the demolition and disposal of the old retaining wall.

@HilfeHilfe: Thank you very much. I will pass the compliment on to our civil engineer/ landscaping contractor. We are celebrating, among other things, a housewarming party on Saturday.

In our new development area, I have often seen people use a (nice) dry stone wall instead of L-shaped concrete blocks, and then pour the actual structural support behind it themselves.

The result is, for example, a nicely finished intact wall that can be built by hand, and behind it, you just have to calculate how many cubic meters of concrete and steel you need. For 30 meters (98 feet) at a height of 1 meter (3 feet), if I haven’t made a mistake in my calculations, that comes to about 10 cubic meters (13 cubic yards) of concrete.

So, even if you have it delivered, the concrete plus steel costs a maximum of $2,000, gravel another $500, plus some consumables and, of course, the concrete blocks, which in my opinion look much better...

Peanuts74 schrieb:
In our new development area, I’ve often seen people use a (nice-looking) dry stone wall instead of L-shaped concrete blocks, and then pour the actual support structure behind it themselves.
The result is, for example, a nicely finished, intact wall that you can build by hand, and behind it you just have to calculate how much cubic meters of concrete and steel you need. For 30 meters and a height of 1 meter, if I haven’t miscalculated, it comes to about 10 cubic meters of concrete.
So even if you have it delivered, the concrete plus steel costs a maximum of 2000 euros, gravel another 500 euros, plus some consumables and of course the concrete blocks, which in my opinion look much better...

A nice dry stone wall can effectively disguise the ugly concrete surface.
However, it makes sense to continue constructing the actual retaining structure behind it with L-shaped blocks. The purpose of the L-blocks is that the weight of the slope being supported rests on the base of the L-block, which provides stability to the wall (in addition to its own weight).
At least for greater heights (e.g., 1.50 meters (5 feet)), the earth pressure on a cast wall alone might be too high. Our neighbor’s wall (built by hand and filled with steel and concrete) has already started to lean a bit over the last 18 months.

What I meant is to cast the concealed concrete wall like L-shaped blocks. Place a steel mesh at the base, add extra reinforcement at the "bend," and include a few vertical rebars as well (ideally bent over the base all the way up to the "top"). Don’t skimp on the concrete and cast these L-blocks yourself in sections of about 2 meters (6.5 feet). Heights up to 1 or 1.2 meters (3.3 or 3.9 feet) are still manageable. If you need around 1.2 meters (3.9 feet), using 0.9 to 1 meter (3 to 3.3 feet) of concrete might be enough, with the rest supported by the dry stone wall.

Make sure to add retarders to the concrete so the base doesn’t harden too quickly, and work efficiently with 2–3 people and a concrete mixer. This should prevent any problems. If you mix the concrete yourself, the cost per cubic meter (including steel reinforcement) is between 100 and 120 euros, so including gravel, you’ll be well under 2000 euros.

Depending on soil conditions, you’ll need to decide whether to excavate by hand or hire a contractor. For average soil, excavation and removal should cost about 500 euros (around 20 euros per cubic meter). This brings the total to just over 2000 euros. However, the stones for the dry stone wall will add to the cost; for approximately 30 m² (320 square feet), expect around 5000 euros, depending on quality and pricing.

For a maximum of 7500 euros, you get a nice wall without a bare concrete surface...