This node can be added to pairs. It prescribes that the relative humidity is continuous across the pair. Continuity is only suitable for pairs where the boundaries match.

Choose the pair on which to apply this condition. A pair has to be created first. See Identity and Contact Pairs in the COMSOL Multiphysics Reference Manual for more details.

Physics Tab with interface as Moisture Transport in Air or Moisture Transport in Building Materials selected:
Pairs>Continuity