The owner of the lower story said to him: I will dismantle the structure and rebuild it. The owner of the upper story said: But then I will have no place to live while you are renovating. The owner of the lower story said to him: I will rent a place for you to live for the duration. The owner of the upper story said to him: I do not want to bother with moving. The owner of the lower story said to him: But I cannot live in my apartment in this condition, as the walls have sunk into the ground. The owner of the upper story said to him: That is not my problem. Crawl on your stomach to go in, and crawl on your stomach to go out.

Rav Ḥama said: By law, the owner of the upper story can prevent his downstairs neighbor from rebuilding. The Gemara comments: And this statement applies only when the beams supporting the second story have not reached lower than ten handbreadths from the ground. But if those beams have reached lower than ten handbreadths from the ground, the owner of the lower story can say to the owner of the upper story: Below ten handbreadths is my domain and my domain is not bound to you to support your residence.

The Gemara further comments: And this statement, that the owner of the upper story can prevent his downstairs neighbor from rebuilding, applies only when they did not stipulate with each other that if the house sinks they will rebuild the house anew. But if they made such a stipulation with each other, they must dismantle the house and rebuild it.

The Gemara asks: And if they made such a stipulation with each other, to what extent must the ceiling of the lower story drop before they implement the stipulation? The Sages said before Rabba in the name of Mar Zutra, son of Rav Naḥman, who said in the name of Rav Naḥman: Like that which we learned in a mishna (98b): If one takes upon himself to build a house for another person, without stipulating its dimensions, its height must be equal to the sum of half its length and half its width. Rabba said to them: Did I not tell you not to hang empty pitchers on Rav Naḥman, meaning not to attribute foolish opinions to him? Rather, this is what Rav Naḥman said: As people normally live, and no more. And how much space is that? Rav Huna, son of Rav Yehoshua, said: The ceiling of the lower story must be high enough so that one could bring in bundles of reeds of the type made in Meḥoza and be able to turn around.

It is further related that a certain man built a wall outside the windows of his neighbor. The neighbor said to him: You are blocking the light with your wall and darkening my house. The one who built the wall said to him: I will seal your windows here and make new windows for you in your wall above the wall that I am building. The neighbor said to him: By doing so you will damage my wall. The one who built the wall said to him: I will demolish your wall until the level of the windows and rebuild it, and then I will make windows for you in the new part of the building above my wall. The neighbor said to him: A wall that is old at the bottom and new at the top will not endure.

The one who built the wall said to him: I will demolish the wall until the ground and entirely rebuild it, and then I will make windows for you in it above my wall. The neighbor said to him: One new wall in an old house will not endure. The one who built the wall said to him: I will demolish your entire house and put windows in the new building that I will erect in its place. The neighbor said to him: But in the meantime I will have no place to live. The one who built the wall said to him: I will rent a place for you to live. The neighbor said to him: I do not want to bother with moving. Rav Ḥama said: By law, the neighbor can prevent him from building the wall.

The Gemara asks: This case is identical to that case; this case is very similar to the previous case of the owner of the upper story who can prevent the owner of the lower story from rebuilding. Why do I need this additional case? The Gemara answers: This teaches us that even if he uses the house only for storing straw and wood, he can still maintain that blocking the light causes him damage and can prevent the neighbor from erecting the wall.

The Gemara further relates: There were two brothers who divided their father’s estate between them. One received a hall [aspelida] in his share and one received a garden. The one who received the garden went and built a wall in front of the opening of the hall. His brother said to him: You are blocking the light with your wall and darkening my house. The one who received the garden said to him: I am building on my property. Rav Ḥama said: By right he said that to him, as it is permitted for him to build there.

Ravina said to Rav Ashi: In what way is this different from that which is taught in a baraita: If two brothers divided their father’s estate between them, one of them taking a vineyard and the other one taking a grain field, the owner of the vineyard has the right to an area four cubits wide in the grain field for the purpose of working the vineyard, since it was on that condition that they divided the estate. Why in this case does the owner of the hall not have the right to make use of the light coming in from the garden?

Rav Ashi said to him: There, the reason is that they made an assessment with each other with regard to the value of the fields, arranging for compensation if one received more than the other, and they took the work area into account. Ravina asked: But what did they do here? Did they not make an assessment with each other? Are we dealing with fools, that this one took the valuable hall and the other one took the much less valuable garden without making an assessment with each other? Rav Ashi said to him: Although they assessed with each other the value of the bricks, the beams, and the boards, they did not assess with each other the value of the airspace. With regard to that, each one retained full rights to his respective airspace.

The Gemara says: And let the one who received the hall say to the other: Initially, you gave me a well-lit hall; now you are making it into a small dark room [idrona]. Rav Shimi bar Ashi said: He gave him only a place that is called a hall by name, that is, a place that is called a hall even though it is no longer used that way.

Rav Ashi continues: Isn’t it taught in a baraita: In the case of one who says to another: I am selling you a beit kor of dirt, it becomes his even if it is only a letekh, i.e., a half-kor, and the sale is not void, because he sold him only a place that is called a beit kor by name. The Gemara comments: And this ruling applies only as long as the land he is selling him is actually called a beit kor. Similarly, if he says to him: I am selling you an orchard, it becomes his even if it lacks pomegranates, because he sold him only a place that is called an orchard by name. The Gemara comments: And this applies only as long as the land he is selling is actually called an orchard. And similarly, if he says to him: I am selling you a vineyard, it becomes his even if it lacks grapevines, because he sold him only a place that is called a vineyard by name. The Gemara comments: And this applies only as long as the land he is selling is actually called a vineyard.

The Gemara rejects this argument: Are these cases comparable? There, the seller can say to the buyer: I sold you only a place that is called that by name; here, the one who received the hall can say to his brother: I took this portion as my share on condition that I would live there the way our fathers lived there, and that you would not change that by blocking the light entering through the windows.

With regard to Rav Ḥama’s ruling that it is permitted for the brother who received the garden to build a wall in front of the hall, they said to him,