Stabilize basement wall for extension

Now without structural engineer advice (I will ask one later), does anyone know of a case where a house collapsed because a basement wall was excavated or is that an urban legend?

Of course, these cases are regularly in the news. For example, "Insurance does not pay after collapse" last year: collapse after excavation work for a drainage.

Sorry, but "above" in the plan. The bathroom window becomes the door.

Ah yes, still on the gable side. I suspect it will be difficult to continue the roof linearly like that. If the extension is to be two stories, I would connect it with a shed roof so that its ridge still lies within the straight section of the gable wall.

The structural engineer is coming by again next week.

He will be pleased. What you uncovered is probably representative. 38 cm walls above the basement were not common back then - even before the war - they used 25 cm. In the post-war supply situation, they certainly didn’t build it as planned. On the other hand: if it has stood for so long, it seems to be stable and robust.

Just for your information, the extension is already planned and approved. Now it's only about the execution and the handling of the [Altbau]. Since I want to do everything myself, I need some advice here and there.

So, I have now opened the wall and yes, the wall is not hollow but alarmingly "cookie-like".
Knock on a stone too hard and it is loose and can be pulled out of the wall.
So filling with concrete is out of the question.

Now, without structural engineer advice (I will still ask one), does anyone know of a case where a house collapsed because a basement wall was excavated or is that an urban legend?

Hello,

A few years ago we bought a settlement house from 1946 in Brandenburg. The walls look exactly like yours in the picture. Since the topic of stability is at the very top of our TO DO list, I wanted to ask if you have now filled the basement walls with concrete etc.?

Thank you very much!

I did not touch the basement walls at all. I carried out underpinning according to DIN. Excavated section by section down to the basement floor and poured concrete blocks in front of the basement wall.