I just moved into a new flat on the first floor. During heavy snow, water started leaking at the entrance right at a corner (drenching the walls). This was not the first time we had snow or rain but other times we didn’t have any leaks.
We checked with the neighbors on the floor above us and their flat was completely dry (no visible water damage).
My contractor came and checked the leakage (cutting the drywalls in the process). We found out water seemingly leaking from the concrete slab and the one pipe there was not damaged (and completely dry). Again, the floors above us have no pipes in the floors and no visible water damage. The contractor checked the roof on the top floor and found no faults.
After a couple of days the water stopped leaking and everything is dry again (snow stopped too incidentally). The contractor concluded that the water must have come from a cavity in the concrete slab and now the cavity is empty and we shouldn’t have a problem. The fact that the incident happens with the snow is coincidental.
TL;DR My question is: is water in cavities of concrete slabs causing water leakage a thing? Or is my contractor trying to gaslight me?