What is the ruling on the prayer of one who precedes the Imam in the prayer area?

Scholars have differed regarding the validity of a congregant's prayer when standing in front of the imam. The majority opinion, which is the most just and preponderant, is that it is invalid unless there is an excuse. The Maliki school of thought, however, holds it to be valid even without an excuse, though it is considered disliked (makruh tanzihi).

Accordingly, if your standing in front of the imam was due to an excuse, your prayer is valid according to most scholars. If it was without an excuse, it is valid according to the Malikis and those who agree with them, and this opinion can be adopted.

As for praying above the imam (on the second floor while he is on the first), it is valid and there is no dislike associated with it.