If a residence is built on the roof of a mosque, does its status as an accessory to the mosque cease?

Question : If a residence is built on the roof of a mosque, O Shaykh, does its status as an accessory to the mosque cease, or is it said that building residences on top of it is prohibited, as some have said, because it is an accessory to the mosque, and it is not permissible for a person in a state of major ritual impurity or a wall to be in it?

Answer : It is not permissible to build a structure for residence on top of a mosque, because the air is an accessory to the ground. However, if a person builds a structure and makes its lower level a mosque, its upper level is not a mosque. Its upper level is not a mosque, and one cannot perform i'tikaf (spiritual retreat) in it, based on the fact that it is above the mosque.