Our kitchen, which was completely renovated in mid-2020, has a mold problem:
It was noticed when water suddenly leaked from under the refrigerator. At first I thought it was a defect in the appliance, but it probably wasn't. We removed the built-in refrigerator and the cabinet it was installed in, and there was horror behind it: There was mold in the bottom corner of the room and on the wall to the side of the refrigerator (see photo). There was mold between the refrigerator and the built-in cabinet. The entire right side wall of the appliance was covered with water droplets.
The craftsmen we know (tiler + plasterer) looked at it and said that it is condensation from the humidity in the air. The air can't circulate properly in this cabinet, hence this problem. Also, the refrigerator is right in the corner of the room on the two outside walls (northeast).
How should this problem be addressed? Removing mold and good drying of everything first is logical.
The tiler said I should install a vent system in the wall above the refrigerator to regulate the humidity. I think this makes sense, but I'm worried that since the cabinet is next to the wall (0.5-1 cm of air at most), condensation will continue to form there despite the ventilation. Are there any additional measures here – perhaps some way to fill in the small cavity?
Additional info: The exterior wall is 30 cm brick masonry with no additional insulation. (Built in the early 70's)