Bava Metzia, chapter six, mishnah seven. This mishnah continues to deal with the rights of the renter, and opens with a question: If someone rents out an apartment or a house to his friend, what is the landlord's responsibility?
The Landlord's Obligations:
A door.
"Neger" - A kind of bolt for locking the door from the inside.
"Manul" - A lock for locking the door from the outside.
Any other infrastructure that can only be done by a professional, classified as a craftsman's work.
The Gemara brings additional examples, such as broken windows. In contrast, things that do not require an expert professional are the responsibility of the renter. Thus, for example, they used to plaster the roofs every year to ensure they were watertight - a job that does not require special training, and therefore the renter is expected to do it himself.
A Dispute Between the Rema and the Gra:
The Rema: This is a one-time obligation. The landlord hands over a functional apartment to the renter, and from then on, the maintenance is the renter's responsibility; if the locks do not work, he must fix them himself.
The Gra: Those basic things that are a craftsman's work remain the landlord's responsibility, and therefore at any stage during the rental period the landlord will be required to fix locks and the like, as well as any job requiring special training - plumbing, electricity, and so on.
It is worth noting that the practical halachah depends on the accepted custom and the prevailing law in that place, which override the law of the mishnah in any case.
The Shared Courtyard:
Here the mishnah opens a new section. City planning in those days meant that a shared area called a courtyard stretched out in front of the apartments - a sort of front yard shared by all the tenants. There they cooked, and there stood the stoves and ovens; there, too, the rest of the chores were done, and any repair or preparation actually took place in the shared courtyard in front. It emerges from the mishnah that the courtyard was often accessible even to passersby.
The question is, if a landlord rents an apartment to a renter and does not include ownership of the front courtyard in the rental - what is the status of the courtyard? Of course the renter is allowed to use it: first, he must pass through it to access his apartment; and it makes sense that he is also given permission to use it for his other outdoor needs, such as cooking and baking, and therefore he will have access to the oven and the stove, which are his private oven and stove. However, the rest of the area does not belong to him, and it remains in the ownership of the landlord.
Based on this, the mishnah states: If a third party moves animals through the courtyard, and the animals leave manure behind them - who has the right to the manure to use as fertilizer? The answer is: the landlord and not the renter. This is not referring to manure produced by the renter's own animals, since the renter does not declare his rights to his own manure ownerless and may take it for himself; but with other people passing through the courtyard with their animals, it can safely be assumed that any dirt they left behind was declared ownerless, and therefore the landlord acquires it.
"Ve'ein lasocher ela hayotzim min hatanur umin hakirayim bilvad" - The renter's right is limited to what comes out of the oven and the stove. Assuming an oven and a stove stand in the courtyard, they are designated for the renter's use, and during the time of the Mishnah it was accepted that he had a sort of private right to them.
Therefore, if a random third party used the oven or stove and ash remained at the bottom - and this ash is useful as fertilizer - who has the right to it? The renter. Since these are his oven and stove, under normal circumstances the ash belongs to the renter and not the landlord.
Here too, everything stated is based on the assumption that there are no overriding customs regarding the standard practice of that time and place. Of course, today things are done very differently, and therefore it is difficult to determine how the halachah rules on this matter at all.