tough mass between masonry and concrete ceiling.

Hello, is this perhaps the "sliding bearing foil" that is placed between walls and ceiling? That is also such a black, solid stuff. Best regards, Andreas

Hi again,

I
Could it be that a welding membrane is laid between the masonry and the filigree ceiling, which has now become somewhat softer due to high temperatures and thus shows through the paint?

Not only could it be, it must be. It’s not a welding membrane, but it looks similar. The ceilings are not fixed to the walls; they need to be able to shift. Hence this "slip sheet."

Best regards,

Andreas

I think that this slide is not a must - and it also does not dissolve or become slimy.

I also think that we don't have any slide film here...

Hi Sebastian,
let's put it this way: I was told by three independent people that a sliding bearing like this is necessary for our house because the clay tiles exhibit different vibration behavior during drying and different thermal expansions than the concrete ceilings. Sounds logical.

You probably built with calcium silicate bricks in Westphalia, maybe it’s different then?

And maybe there are other sliding bearing systems than the foil installed in our case. It’s just a guess what it could be at Musketier...

Best regards,

Andreas

For us, it is aerated concrete. So it can be different again.

My wife immediately panicked after she saw something black up there. However, I rule out water damage or mold. Maybe something was stuck underneath the filigree ceiling.