Richard Fangnail wrote
Rod Speed wrote
Richard Fangnail wrote

In my apt the tapping noise can come from my ceiling or one of the
walls. When the tapping got bad a few weeks ago, it got bad in both
places at once. Why would that happen, if the problem is due to the
pipes rubbing against the holders?

Presumably the same corrosion etc is affecting both.

What corrosion are you talking about?

Between the pipe and what is used to attach it to the structure.