The structural integrity of a sheet of Extremegreen MgO is not compromised by exposure to water. That is a lot more than can be said for gypsum board and cement board, which almost always has to be replaced after a flood, or even an air conditioning leak.
Not only will Extremegreen MgO withstand the worst that nature can throw at it, it will not feed mold or mildew once the flood has subsided.
Say goodbye to water damage. Say hello to peace of mind.