How high should the slope be for frost resistance?

Hello dear forum,
We are working on our outdoor area outside, we are the last ones, everyone else is already finished. As can be seen in the pictures, we are on a steep slope. Now the neighbor wants us to frost-proof his garage by adding fill. The landscaper wants to add fill up to the street level, according to the district office this is also acceptable. I know he built it about 20 cm higher than allowed so he can get into the garage better.
We cannot add fill any higher; our terrace is also right next to it. Do you have any idea how this can be done without disputes and what the legal situation is? Do I have to ensure that his garage remains frost-proof!?

The neighbor has apparently aligned himself with the finished level of the street, but legally I see the question more as to who among you made the terrain change. That is, whether the height difference between your properties resulted from you staying at the original level at the boundary and he having built up, or he stayed and you dug down. Only in the latter case do I see this as being at your expense to achieve the desired condition—if he built up, he should have considered your non- or lower buildup and possibly excavated deeper himself. Then I would at least see him obligated, if he neglected this, to compensate you for your additional effort. It cannot be your "pleasure" to lose more of your garden to a slope. The terrain changer is also burdened with the slope load. Considering this in the case of boundary garages should not be passed on to the neighbors.

We are doing our outdoor area outside, we are the last, everyone else is already finished. As can be seen in the pictures, we are located on a steep slope. Now I want

The neighbor has apparently aligned themselves with the finished level of the street, but legally I see the question rather as to who of you made the terrain alteration. That means whether the height difference between your properties resulted from you staying at the original level at the boundary and they filled up, or they stayed and you excavated. Only in the latter case do I see this as being at your expense to create the desired condition – if they filled up, they should have considered your non- or lesser filling and, if necessary, laid foundations deeper themselves. In that case I would at least see them as responsible; if they neglected this, then they should compensate your additional expense. It can’t be your “pleasure” to lose more of your garden to a slope. The terrain modifier also bears the slope load. Considering this for boundary garages should not be shifted onto the neighbors.

Thank you for the answer,
I have now found an old photo! The neighbor’s scaffold stands on our property, that is the original terrain. As you can clearly see, it slopes down towards the garage. In my opinion, I hardly have to add any fill. Also see the rock at the back toward the other neighbor. It looks flush.

I really can’t see it clearly in the photo, but I interpret your words as an answer that you did not dig down. The neighbor probably aimed not to have the garage door threshold below street level. If he naively speculated when designing his foundations that you would also be filling up and accordingly saved on frost-proofing below your existing ground level, that was his mistake, which is not your responsibility to fix. So if the difference between his actual foundation depth and the frost-proof depth is not your fault, he can’t demand anything from you. Any potential building damages would be his own responsibility. Making the slope higher would have meant less flat land up to the base of the slope for you and slight disadvantages for rainwater infiltration on your property. Whether this effect is so significant that your drainage would be more expensive, I consider unlikely but cannot say for sure.

we can’t slope higher, our terrace is right next to it.

As long as this only concerns a terrace within the permitted range, this would indeed be a relevant limitation for you to slope more. I see the following disadvantages for you, assuming you want to be nice and fulfill his wish without legal grounds: 1. more filling (material and time); 2. less flat land up to the base of the slope (or even a narrower terrace, possibly alternatively a steeper slope); 3. difficulty with infiltration.
I would probably offer the following measures: a Birco channel along the edge of the slope base versus the terrace, discharging into a soakaway trench or cistern; he would pay for this measure including the additional expense; likewise, he would cover the costs of your lawyer’s contract and its notarized certification; in my opinion, that should be the end of it for you. It would probably have been cheaper if he had excavated and concreted 20 cm deeper, but as I said: that was his mistake. No one has the right to demand that their neighbor must also belong to the fillers’ faction. Perhaps also has an opinion on this.

Maybe @Escroda also has an opinion on this

Monika's brother is seeking advice elsewhere. There is more information there, but organizing it causes me problems. There is talk of €100 paid for the permission to build the slope, of 25cm of filling and 30cm of removal, of subsequently removed topsoil, and similar things.
Solution according to the facts mentioned here: Monika builds a raised bed along the garage wall with the written obligation to maintain and preserve it, and the neighbor covers the material costs.

Monika's brother is asking for advice elsewhere. There is more information there, but I have problems sorting it. There is talk of €100 paid for permission to create the embankment, of 25cm of filling and 30cm of excavation, of topsoil removed afterwards, etc.
Solution according to the facts given here: Monika builds a raised bed along the garage wall with a written obligation to maintain and preserve it, and the neighbor covers the material costs.

Hello
Thanks for the reply.
Yes, it is a bit confusing, the €100 refers to something else. In the last photo I took, you can clearly see a hill full of soil. When the neighbor's scaffolding was gone, we had this soil distributed by a landscaping gardener; he then spread it along the garage at our neighbor's request, for the purpose of winter and frost protection.
Two years later, that is this Wednesday, we removed the soil again and used it elsewhere. The neighbors then thought we had excavated and now had to build back up the embankment... we explained that it was only the piled-up soil from the hill, the man still remembered it and apologized.
I know that they built higher than allowed, a construction worker from their side told me that before they moved in... the purpose was for him to be able to drive into his garage better... now we naturally think that he is missing that part... we can set off the bomb now because we do not accept that fraud should be rewarded and that we only do what is permitted or approved.
The single-family house between our houses is about 3 meters wide.
I am just wondering how I can prove that I do not have to excavate but rather fill up. No more, no less. I didn’t think we needed such a high embankment.
1. He can now drive better into his garage
2. We are supposed to make his garage frost-proof.
3. There is a raised bed on the garage which counts as an extension and now makes the garage even higher; in summer I have neighbors directly above me who can look onto my plates. We were not even asked...
I get along well with our neighbors because until now we have not said anything, and we still wouldn’t have said anything;
But now it is outrageous to demand from us what they messed up...