Eruvin, Chapter 5, Mishnah 4. In this mishnah we learn that the only place where the eruv may be deposited in a courtyard is a place where, if a person were living in it, he would be required to join in the eruv of courtyards. The rule works in reverse as well: a place that does not qualify as a significant living area not only fails to create a need for its resident to join the eruv, but cannot even serve as a place to deposit the eruv itself.
The words of the mishnah:
"HaNosein es eiruvo b'veis sha'ar, achsadrah o mirpeses - eino eiruv, v'hadar sham eino oseir alav" - one who deposits his eruv in these places has accomplished nothing. And these are they:
"Beis sha'ar" - the gatehouse or watchman's booth that would be set up before the entrance to the courtyard.
"Achsadrah" - an open area that has only a roof, without walls.
"Mirpeses" - a balcony, in its plain sense.
The eruv must be placed in an enclosed space, and therefore depositing it in these places does not count as an eruv. And since these are not significant living quarters, a person residing in them likewise does not create a restriction: if there is one other resident in the courtyard, and another person lives in one of these places, together they do not create the need for an eruv.
"Aval b'veis hatevven, b'veis habakar, b'veis ha'eitzim uv'veis ha'otzaros - harei zeh eiruv, v'hadar sham oseir alav" - and these are they:
"Beis hatevven" - a storehouse used for storing straw.
"Beis habakar" - an area used for livestock.
"Beis ha'eitzim" - a place for storing wood.
"Beis ha'otzaros" - any other kind of storeroom.
In these places depositing the eruv is effective, and consequently a person residing in them does create a restriction and generates the need to join in the eruv.
Rabbi Yehudah's qualification:
Rabbi Yehudah adds: "Eimasai? Bizman sheyeish sham tefisas yad shel ba'al habayis" - when a person lives in one of the places that generate a need for an eruv, and even if it is an actual house that he rents, if the landlord who rented it out retains a "tefisas yad" there - that is, the right to keep in that place items of his own that do not belong to the renter - the renter does not create a restriction, since he is considered subordinate to the landlord.
The Gemara explains that the items the landlord keeps there must be items that cannot be moved on Shabbos. For if they could be moved, the renter might remove them on Shabbos, and then the landlord's "tefisas yad" would be nullified and his control over that area would cease. Consequently the resident, whether the renter or whoever lives there, would acquire the rights to the place and would become one who creates a restriction, generating the need to join in the eruv.
In summary: in this mishnah we learned the link between a place's fitness for depositing the eruv and the power of its resident to create a restriction: a gatehouse, a portico and a balcony are not places for an eruv, and one who resides in them does not create a restriction; a straw shed, a cattle shed, a woodshed and a storeroom are fit for depositing the eruv, and one who resides in them does create a restriction. And according to Rabbi Yehudah, all of this applies only when the landlord has no "tefisas yad" in the place - for if his items that cannot be moved on Shabbos remain there, the resident's standing is nullified and he does not create a restriction.