A home/room that contains a gentile:
If one of the occupants of a home or room is a non-Jew, such as a home or room that is jointly owned or rented by a Jew and non-Jew, it is exempt from having a Mezuzah. [Some however conclude that one is to place a Mezuzah without a blessing. If the gentile does not live in the home, then it is obligated in a Mezuzah while the Jew is living there, even if the gentile is one of the owners of the home.]
Does the gentile maid’s room in one’s home require a Mezuzah?
If one has a gentile roommate, is he obligated to place a Mezuzah on his doorpost?
If the gentile sleeps in his room, then all the rooms of the house are exempt from a Mezuzah. If the gentile has his own room within the house, then the Jew’s personal room is obligated in a Mezuzah while the other rooms are exempt.
If one allows his gentile friend to sleep with him in the same room, is he obligated in Mezuzah?
 Rama 286/1; Kitzur SHU”A 11/19
Other Poskim: Some rule that the room is obligated in a Mezuzah. [Rashba; See Pischeiy Shearim 286/39]
 The reason: The reason for this is because 1) Part of it is owned by a non-Jew and is thus exempt from having a Mezuzah. 2) It may be dangerous, as the Non-Jew may suspect that the Jew is doing witchcraft on him. [Shach 286/6] 3) We learn that partners are also obligated in Mezuzah from the words “To increase your days” which is not applicable to non-Jews being that they do not fulfill the Torah, and thus are not deserving of long days. [Taz 286/2] The Shach ibid negates this latter reason.
 See Aruch Hashulchan 286/2; Pischeiy Shearim ibid; Shulchan Melachim on Kitzur ibid in name of Chida
 Shulchan Melachim 11/165 in name of Mikdash Me’at 286/7
 Aruch Hashulchan 286/3
 The reason: As the room is considered as part of the Jewish owners property which is used on his behalf, to house his maid, and is not similar to a room rented to a gentile, of which the room legally belongs to the gentile. This is similar to the obligation of placing a Mezuzah on the door of the children’s rooms in ones house, even though the children are below the age of Mitzvos. [Aruch Hashulchan ibid]
 Shvus Yaakov 3/89