To limit the probability of inadequate moisture protection, which could lead to an unacceptably high rate of surface corrosion, which could lead to a loss of strength, which could lead to an inability to resist expected gravity loads.
For floors and elements supporting floors, this is to limit the probability of:
This is to limit the probability of excessive deflection or vibration of floors, which could lead to persons losing their balance, tripping or falling, which could lead to harm to persons.