Shulchan Arukh, Yoreh De'ah 286/שולחן ערוך·יורה דעה רפ״ו

1Places that require a mezuzah. These are the places that require a Mezuzah. Whether the gates of the houses, or the gates of the courtyards, states and cities, [all are the same] and the cowshed of cattle, and the pen, and the storehouses of wine and oil and a woman's house [or room] and the house of the Jewish housemates.They are all obligated. Rema: Specifically when the housemates are Jewish. But the house of a Jew and an idolator, is exempt from a Mezuzah (Mordekhai on Avodat Kokhavim ch. 1 end). Also the courtyards of cities where some idol worshippers live are exempt from Mezuzot (Chidushei Agudah on Yoma, ch. 1).

2A house/room for straw, wood, livestock — require. But if women bathe there, since they stand there naked, it is not proper regard of Heaven for a mezuza to be there. Rema: Only these specifically. But an actual [living] room, even if man and woman sleep and have relations there — requires mezuzah (in Responsa Maharil and the same wrote the BY) And some are lenient and say wherever women lie is exempt from mezuzah (BY in the name of Semak, the Kol Bo, and Mordekhai Hilkhot Mezuza end.) It seems to me wherever the door is from the [room's] inside and when people sleep there they close the door, and a doorpost is found outside it — it requires by all opinions. (Own opinion in Darkhei Moshe. And thus it seems in Teshuvat Maharil #98).

3A synagogue, if there is an apartment for anyone, requires a Mezuzah. Rama: And if there is an apartment in the courtyard that is in front of the synagogue, the courtyard needs a Mezuzah but the synagogue is exempt. (Beit Yosef in the name of Rabbeinu Yerucham).

5Where there's filth e.g. if there are babies there, it's better to cover the mezuzah. In a clean place it's better to have it visible.

6An porch, which is a space with three walls and a roof, even though it has two uprights on the fourth side petzimin, the akhsadra is exempt, because the petzimin are made to support the roof and not for the sake of mezuzoth/doorposts. (Quoting Rambam: Sefer Torah 6:3) But if it has a wall on the fourth side as well, even if it is low or is composed of many windows, then it requires.

7A balcony that is a path to go up some stairs, and hallway [beith sha`ar], and a garden, is exempt. But if the house opens to one of these, it requires. (And some say a hallway [beith sha`ar] requires one even if the house does not open to it (Tur and the poskim in the name of R"Y).

8A gatehouse (hallway) that opens to a room and to a yard, needs two mezuzot: one where it open to the room and one where it opens to the yard.

18A house that has many doorways, even though he normally only exits and enters through one of them one, he is required to make a Mezuzah on each one. Rema: Since they are made for entry and exit. (Thus seems to say the Tur) A cellar that has an entry from the street, where they bring in wine in large barrels and it has a doorway from the house through which they enter and exit it constantly: If the small doorway [inside] is fit to have a mezuzah, then it requires it and the large doorway [outside] is exempt. But if the small one is not fit to have a mezuzah, then the large one requires it and the small one is exempt (Beit Yosef in the name of an Ashkenazi responsum, which is found in Responsae Maharil #99).

22One who rents a house/room outside the Land, or one who lodges at an in the Land of Yisrael, is exempt from Mezuza for thirty days. But one who rents a house/room in Eretz Yisrael requires Mezuza immediately, due to yeshuv (dwelling in) Eretz Yisrael. (And this is the law for someone who borrows a house; the law is like the renter.) (Beit Yosef in the name of Rabeinu Manoah and so it seems in Shas)