If you install the cistern of the WC, for example, on the front wall of an exterior wall and the area behind it is not plastered, you no longer have an airtight layer and drafts will come through the cistern...
If you install the toilet cistern on the front of an exterior wall and there is no plaster behind it, you no longer have an airtight layer and there will be drafts through the cistern...
Yes, basically understood and it would also be logical from my point of view if no exterior plaster is applied, right? I'm just asking because I want to understand. As shown in the photo above, the area behind the toilet cistern is filled with putty.