ᐅ Is it acceptable to insulate a toilet pre-wall installation with leftover glass wool?

Hello,

we have just started renovating our bathrooms. Our toilet is located against an exterior wall that is insulated from the outside with 160mm (6.3 inches) insulation.

Inside, the contractor has now installed drywall on the stud wall, and I noticed that he filled the cavity with leftover glass wool.

Now I’m wondering, aside from the benefits like soundproofing and additional thermal insulation, isn’t this actually an unnecessary risk in terms of mold or moisture? Could moisture not penetrate into the cavity, causing the glass wool to absorb it and start to mold?

For the wool inside the 160mm (6.3 inches) insulation to develop mold, it would have to be quite cold.

Filling the cavities is sensible to avoid large resonance chambers—especially near toilets. This makes the flushing much quieter. Additionally, the wool prevents condensation from forming on the outside of the flush tank (i.e., on the exterior of the container behind the drywall).

Mold problems are not expected there, since the entire area is sealed off and located on the interior side of the wall, in front of the actual insulation layer.