What are the conditions to do Tayamum? Can a person do Tayamum if the obligatory prayer in the Masjid is going on and he feels that he might miss any Rak’ah keeping in mind that Tayamum takes lot less time than Wudu?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The conditions of Tayamum (dry ablution) are:

1)     To use pure soil; which is according to most scholars: sand.

2)     Tayamum has to be done after the fixed time of the prayer for which it is done enters.

3)     Tayamum is not valid unless there is no possibility of getting or using water.

There are two reasons for which one can make Tayamum instead of Wudu.

1)     Inexistence of water.

2)     Fear of using water which includes fear of fetching it or fear of getting sick because of using it or fear that one’s illness might get worse because of water or its cure might be delayed.

From the above, you know that it is unlawful for the person to make Tayamum just for fear of missing a Rak’ah as this is not a reason that make Tayamum lawful.

Allah knows best.