My daughter has a small condo in an old, former school building in CT.

The bath drain in the condo above her bath is leaking and damaged the sheetrock in her bath ceiling. She wants to replace the bathroom fan and put it directly over the tub. I told her that in that case it should be on a GFCI circuit.

The problem is that the cavity – brick and concrete lined – between her bath ceiling and the concrete floor of the bath above has no outlet to outside air.

Is she better off having no fan at all? Or does it make any sense to have a fan which is venting warm, moist air into the cavity described above?

Chuck