After we were confronted with the „oh, we are going to underpin you now“ situation, we felt compelled to communicate various matters to our neighbor in writing. Especially because in a phone call with his architect, he was of the opinion that with a 30cm difference no underpinning would be necessary, but they could simply dig deeper.
Also, obtaining legal advice proved quite helpful. According to the Neighbor Law in BW, we are not obliged to tolerate underpinning. For such a project, we would also have to be informed two weeks before the start of construction with all necessary documents about what exactly is going to happen to our foundation. Allegedly, they are about to start construction – nothing has happened. A soil survey, which would also include a foundation recommendation, has not been carried out yet. Neither has there been a request for our or the neighbors‘ civil engineering documents. And that, although they are building in a gap between buildings.
We have now, as a precaution, objected to the underpinning and clearly stated again what their and our rights are and that we are concerned about the safety of our building in such a planning scenario. Should they start anyway, we would seek a stop-work order.
Our suggestion now would be that we jointly find a planner who develops a reasonable foundation proposal, which according to DIN 4123 is to be carried out by a specialist company and whose execution is also supervised by an expert. Before the start of construction, of course, the current intact condition of our house must also be inspected and approved by the expert, should there be any settlements, etc. The costs must, of course, be borne by the neighbor.
We did not actually want to take this step. However, after the statements of the architect and neighbor, we were so astonished by their professional shortcomings that we saw no other choice.