Rambam - 1 Chapter a Day

For the house is the responsibility of its owner.

I.e., the court will issue an order to this effect and expropriate property belonging to the owner of the house, if necessary (Kessef Mishneh).

For otherwise his loft will fall.

Because the existence of the loft is not considered an advantage to the owner of the home. On the contrary, by and large it is considered preferable for the owner of a home that no one live in the loft.

The Maggid Mishneh points to Hilchot Sechirut 6:4, which appears to indicate that both the ceiling and the plaster above it are the responsibility of the owner of the house. The Maggid Mishneh, however, explains that there is a difference between a rental arrangement as described in Hilchot Sechirut, and a relationship between two owners as described here.
The Shulchan Aruch (Choshen Mishpat 165:1) quotes the Rambam’s ruling. The Tur and the Ramah differ and maintain that the owner of the loft bears the entire responsibility for the ceiling.

Provided that the two structures were originally of equal size. If not, the building materials should be divided proportionately [Maggid Mishneh; Tur, Ramah (Choshen Mishpat 164:3)].

This applies even if all the building materials are located in the property of one of the owners (Sefer Me’irat Einayim 164:10).

The Tur and the Shulchan Aruch (Choshen Mishpat 164:4) add that if the owner of either of the stones claim to recognize the stones coming from his property, he is given those stones, and the other partner is given an equal number of the other stones.

The commentaries (Maggid Mishneh, Kessef Mishneh and others) question: Why can’t the owner of the loft compel the owner of the house to rebuild the house, as mentioned in Halachah 1 with regard to the rebuilding of a room?
Two answers are given:
a) The owner of the house traveled overseas. In such a situation, the court does not have the right to expropriate his property.
b) While the house is standing, the owner of the loft can compel the owner of the house to build it. Once it has fallen, however, the option of building it or not belongs to the owner of the house. For if he chooses not to build it, the owner of the loft need not remain homeless. He can rebuild the house and dwell within.

He does not have to pay any rent to the owner of the house. Nevertheless, if ultimately the owner of the house reimburses him, the fact that he lived in the house rent-free is not considered to be interest, because the owner of the house is required to provide him with a place for the loft (Sefer Me’irat Einayim 164:14).

Because they are too poor, or because of government regulations.

I.e., they can use the land as a field or sell it to another person to build up on.
Bava Metzia 117b explains the rationale for the division as follow: The presence of the loft devalues the house by one third. (Sefer Me’irat Einayim 164:15 interprets that to mean that if the house would normally last 90 years, because the loft was built upon it the house will last only 60 years.) Since the owner of the house accepted a loss of one third of his house’s value when be originally granted permission to build the loft, he must give one third of the land to the owner of the loft.

For this is of benefit to the owner of the loft. Now the building will be sturdier, and there is less chance of the loft’s falling.

As Chapter 2, Halachah 18, states, a wall of stone is five or six handbreadths thick, while a wall of brick is three handbreadths thick.

For he is minimizing the sturdiness of the wall and creating a risk for the owner of the loft.

For this provides greater support for the loft.

For this provides less support for the loft.

For both these changes make the walls weaker and provide less support for the loft.

For both these changes make the walls stronger and provide more support for the loft.

Because this reduces the pressure on the lower wall.

As above, this reduces the pressure on the lower wall.

For this causes greater stress on the walls of the home.

For both these changes make the loft lighter and reduce the pressure on the walls of the house.

For both these changes make the walls heavier and increase the pressure on the walls of the house.

The Rambam appears to be explaining that the beams of the ceiling sank independently of the walls. Rashi (in his commentary on Bava Batra 6b, 7a, the source for this halachah) interprets this to be referring to an instance where the wall sank into the ground. Regardless of the interpretation, the result is the same; the ceiling of the home is lowered and its owner has less living space. [Note the Tur and the Ramah (Choshen Mishpat 164:2), who follow Rashi’s approach.]

Any distance lower than this is considered to be an unlivable space. (See Hilchot Sukkah 4:1.) It is as if the house had collapsed entirely.

For his loft is still intact. If, however, the owner rebuilds the home in the process, the owner of the loft will have to seek different accommodations.

I.e., as stated in Halachah 1, the restoration of the ceiling and the plaster above it is the responsibility of the owner of the house (Maggid Mishneh).

See a parallel in Chapter 7, Halachah 8.

I.e., the olive press has an opening to the side of the mountain, but the mountain continues above it, and on the slope of that mountain there is a vegetable garden.
An Olive Press Built Below an Overhanging Vegetable Garden
a) The Vegetable garden
b) The olive press

I.e., and grow horseradish or other plants that do not require rainfall (Sefer Me’irat Einayim 165:2).

Sefer Me’irat Einayim 165:1 explains that the owner of the garden can sow the entire earth of the olive press, for we assume that he would desire to sow one continuous area, and not a little portion of the top and a little portion of the bottom.

Both of them claim the vegetables. The owner of the higher garden says: “They grew from my land.” The owner of the lower garden states: “They grew in my space.”
Two Vegetable Gardens on the Slope of a Mountain
a) The Upper Garden
b) The Property Line
c) The Lower Garden

For essentially, since the vegetables are rooted in his property, they should belong to him.

Rashi (Bava Metzia 118b) explains that, in such a situation, the owner of the upper property would have to ask permission from the owner of the lower property to enter his garden and pick the vegetables. It is embarrassing for him to do that, and so he forgoes his claim to these vegetable.

This situation reflects an unresolved question in Bava Metzia 119a. Since the question is unresolved, and the vegetables are in the space belonging to the owner of the lower property, the owner of the higher property should not take them. For his claim to them is not substantiated. If, however, he does take them, they should not be expropriated from him, because his claim has not been refuted either.

And all the fruit grows in his property.

Since the tree derived its nurture from both the neighbors’ properties, they both are entitled to a share of its fruit. By the same token, if the trunk of a tree is rooted in the property of one neighbor, he is entitled to all the fruit even though the tree’s branches extend into the other neighbor’s property [Tur and Ramah (Choshen Mishpat 167:2)].

We have translated the Rambam’s words literally. The Maggid Mishneh and the Kessef Mishneh [and similarly, the Tur and the Shulchan Aruch (Choshen Mishpat 168:1)] state that this applies only in Eretz Yisrael, our holy land, whose settlement is given special consideration. In the diaspora, when trees are uprooted together with the land around them, by contrast, the owner is granted permission to take back his trees.
Other commentaries (the Meiri and Rav Moshe Cohen) maintain that, according to the Rambam, this law also applies in the diaspora. The Or Sameach supports this contention, noting that in Chapter 6, Halachah 2, the Rambam explicitly mentions “the settlement of Eretz Yisrael,” while in Chapter 14, Halachah 1, when describing laws that apply also in the diaspora, the Rambam uses the same wording as in this halachah: “in order that the land be settled.”
The concept “in order that the land be settled,” is interpreted to mean that the land be used for productive purposes. If the trees were not left in the property of the person in whose domain they were transplanted by the river we fear that this person would not plant trees in his field, for he had not planted trees there before. The person who originally owned the trees will probably plant other – for he had planted them before.

And become the property of the owner of the field.
The Ra’avad protests the Rambam’s ruling, explaining that the owner of the field must pay the owner of the trees the market value of his trees.
The Maggid Mishneh defends the Rambam’s ruling, citing Hilchot Gezelah Va’Avedah 6:3, which states that when property – even property with a mark through which it can be identified – is washed away by a flooding river, the owner despairs of its recovery. Hence, when the trees are not washed away with earth, they become the property of the owner of the field. If they are washed away together with earth, by contrast, the owner will not think that they will be carried far, and he will not despair of their recovery. Hence, the trees would rightfully be able to be taken by their owner except for the special consideration due Eretz Yisrael.
In his Kessef Mishneh, Rav Yosef Karo mentions the Maggid Mishneh’s approach. He also suggests that the Rambam might have shared the Ra’avad’s feelings, but was concise in his words and did not elaborate. In his Shulchan Aruch (Choshen Mishpat 168:1) he incorporates the Ra’avad’s view. He also adds that if the owner of the field does not desire the trees, he may compel their owner to take them.

I.e., enough earth so that the trees could derive nurture from it even if they were not replanted. In such an instance, the trees are considered as if they had not been uprooted, and the laws of orlah – in which the fruits of a tree are forbidden for the first three years after its planting or replanting – do not apply (Hilchot Ma’aser Sheni 10:12).

Since the owner of the field benefits from the fact that the laws of orlah do not have to be observed, he shares that benefit with the owner of the trees.

But not the fruit, for the fruit is forbidden as orlah.

For the trees themselves are movable property, and movable property washed away by a river belongs to its finder, as explained above (Maggid Mishneh).

I.e., in this situation as well, at times the owner of the land and the owner of the trees share in the olives, and at times all the olives are given to one party.

Because the olive grew from the nurture of his land (Sefer Me’irat Einayim 168:6).

Since the owner of the land allowed the trees to remain there for an undefined duration of time, we assume that he was willing to forgo the benefit from his land for this period (Kin’at Eliyahu).

Since the profit is so small, the owner of the land will not mind ceding it to the owner of the trees.

For each one has a just claim. The owner of the land asserts “Without my land, the olives would not have grown.” And the owner of the trees counters: “Without my trees, the olives would not have grown.”