Building a retaining wall in the garden: formwork stones or L-stones?

Your support will transfer the force into his support, where else should it go. And the support of the neighbor is not designed for that.

That could quite possibly be the case.

How far do I have to stay away from the border so that nothing slips away? We want to hire a for this question. To what extent does a structural engineer have to take responsibility in case of a slip? How far does the neighbor have to?

LOL - what use is a distance to the border? Normally, with a slope, 45 degrees should not be exceeded in soft soil (without structural proof). So at 2 m excavation from the neighbor, that is already 4 m distance (slope) to your retaining wall. Then also consider that the retaining wall exerts considerable pressure with the soil behind it. I would rather keep double that distance and then slope. Thus, your retaining wall and then 8 m slope to the neighbor’s final level. Foundation also with adequate depth and concrete. And how will drainage be done then? By the way, please post photos again. What does the terrain currently look like? How exactly is the neighbor planning? What have you (are you even talking to each other?) discussed together? How much space do you have?

Then it probably only remains "Together we can do it!". Everything else will be a disaster.

P.S. You can't prevent the visual disaster at the neighbor either...

Visual disaster is the right description. If I imagine having to look at a 3m high retaining wall :eek: Has the neighbor already implemented the excavation like that? How is it secured so far? Regarding excavation of property, §909 of the Building Code regulates exactly who is responsible for what. We have dealt with it because we are also on a slope and had to excavate on one side as well (however, only 1m).

In the end, there's no other option but to build a 3m high wall. The OP probably doesn't care what the neighbor looks at. It would be better if you both created a terraced garden, then maybe about 1.5m would remain at the border that would have to be retained with L-shaped stones.

I also find that a terraced garden offers a nice way to create structure. At the very top, trees can be planted, one level below flower beds, and then a lawn area for the children to play on.

I see this all the time around here, neighbors putting up 1.5-2m high concrete walls so that the entire property has exactly the same level.

3) approximately how much does this fun cost me per running meter? Does anyone have relatively recent experience values?

Since we are also planning a formwork block wall, maybe the following guideline prices help you (offer as of 12.2023, all net prices):

Excavation of foundation trench 1x0.6x0.8: €43.00 per rm Concrete foundation C25/30 1x0.6x0.8: €130.00 per rm Formwork block wall 50x36.5x25, incl. reinforcement & concrete: €197.00 per sqm Cover slabs: €36.00 per rm Drainage:

... as the forum currently does not allow editing...

Drainage: €37.00 per linear meter
Dimpled membrane: €10.70 per square meter

We will have approximately 20 linear meters, with an average height of about 1.5 m, therefore similar to yours.

However, the situation regarding the neighboring property will certainly make everything more complicated and probably more expensive.