The Ruling on a Menstruating Woman Entering a Building attached to the Mosque

Question:

In America, there is a mosque comprising three floors: The top floor is a prayer room for women, and the floor below it is the main prayer room, and below it is a kind of cellar, in which are the places of ablution, a place for Islamic magazines and newspapers, classrooms for women and also a place for all the women to pray. Is it permissible for menstruating women to enter the lower floor? Also in this mosque there are pillars which obstruct the worshippers, dividing the ranks into two, does this cut the rows or not?

Answer:

If this building which you mention is considered to be a mosque, and the people on the upper and lower floors hear the voice of the imam, the prayer of the people on all the floors will be accepted, and it would not be permitted for menstruating women to sit in the place which is considered a prayer place for women on the lower floor, because it is a part of the mosque, and the Prophet (SAW) said:
”I do not allow a menstruating woman to enter the mosque, or a person who is Junub” [Abu Dawud no. 232]

As for her passing through the mosque to pick up some things, so long as she is careful not to spill any blood, there is no sin that, based upon the words of the Prophet (SAW):
”...nor the one who is junub, except those who are passing through.”

And the authentic narration from the Prophet which states that he ordered A'ishah, may Allah be pleased with her, to bring him the prayer mat from the mosque, and she told him that she was menstruating, but he said:

”Your menstruation is not in your hands” [Muslim no. 298 & Ahmad 2:86, 6:45]

However, if the lower floor is not intended as a part of the mosque, but only as a storage place and a place as mentioned by the questioner for leaving things, then it does not carry the ruling of a mosque, and it is permissible for the menstruating woman and the one who is Junub to sit in it, and there is no legal objection to praying. But whoever prayed therein should not follow the Imam above him, if he cannot see him or any of the other worshippers, because it would not be considered part of the mosque, according to the most correct of two opinions held by the scholars.

As for the for the pillars which divide the ranks, they do not harm the prayer, but if it is possible to place the row in front of the pillar or behind it, so that it does not break the row, it would be better and more complete. And Allah is the Granter of success.

Source:
Shaykh `Abdul-`Azeez Bin Baz
Fatawa Islamiyah, vol.1, p115-116, DARUSSALAM.