Jerusalem Talmud Bava Metzia 10:3

משנה: הַבַּיִת וְהָעֲלִייָה שֶׁל שְׁנַיִם שֶׁנָּֽפְלוּ אָמַר בַּעַל הָעֲלִייָה לְבַעַל הַבַּיִת לִבְנוֹת וְהוּא אֵינוֹ רוֹצֶה לִבְנוֹת הֲרֵי בַּעַל הָעֲלִייָה בוֹנֶה אֶת הַבַּיִת וְדָר בְּתוֹכוֹ עַד שֶׁיִּתֵּן לוֹ יְצִיאוֹתָיו. רִבִּי יְהוּדָה אוֹמֵר אַף זֶה דָּר בְּתוֹךְ שֶׁל חֲבֵירוֹ צָרִיךְ לְהַעֲלוֹת לוֹ שָׂכָר אָלָּא בַּעַל (הַבַּיִת) בוֹנֶה אֶת הַבַּיִת וְאֶת הָעֲלִייָה וּמְקָרֶה אֶת הָעֲלִייָה וְיוֹשֵׁב בַּבַּיִת עַד שֶׁיִּתֵּן לוֹ אֶת יְצִיאוֹתָיו. MISHNAH: If the ground floor and the upper floor belonging to two different persons collapse, and the owner of the upper floor suggests to the owner of the ground floor to rebuild but himself refuses to build, then the owner of the upper floor rebuilds the ground floor and dwells in it until he¹¹The owner of the rights to the lower floor. pays his¹⁰The owner of the rights to the upper floor. expenses. Rebbi Jehudah says, but he who dwells in another person’s [place] would have to pay him rent²⁶His problem is that if the owner of the ground floor pays his share, the owner of the upper floor will have dwelt in the apartment rent free, which amounts to receiving hidden interest.; so the owner of the (ground)²⁵Clearly one has to read הָעֲלִייָה “the upper floor” with the Babli and all Mishnah mss. floor builds ground and upper floors and makes the roof over the upper floor²⁷To make the upper floor livable, even if he does not dwell there. but dwells on the ground floor until he¹¹The owner of the rights to the lower floor. pays his¹⁰The owner of the rights to the upper floor. expenses.

הלכה: הַבַּיִת וְהָעֲלִייָה כול׳. אֶלָּא בַעַל הַבַּיִת מְבַקֵּשׁ לִבְנוֹת וּבַעַל הָעֲלִייָה אֵינוֹ רוֹצֶה. מָהוּ שֶׁיֹּאמַר לוֹ. גּוֹפְיָנוֹ. נִישְׁמְעִינָהּ מֵהָדָא. הָֽיְתָה חוֹרְבָתוֹ סְמוּכָה לְחוֹרְבַת חֲבֵירוֹ. עָמַד הַלָּהּ וּבְנָאָהּ בְּלֹא רְשׁוּתוֹ הֲרֵי זֶה מְחַשֵּׁב יְצִיאוֹתָיו כְּשַׁעַר שֶׁבָּנָה וְיִתֵּן לוֹ אֶת כָּל־יְצִיאוֹתָיו. הָדָא אָֽמְרָה. שֶׁאֵינוֹ אוֹמֵר לוֹ. גּוֹפְיָנוֹ מִן הַצַּד. כְּשֵׁם שֶׁאֵינוֹ אוֹמֵר לוֹ. גּוֹפְיָנוֹ מִן הַצַּד. כָּךְ אֵין אוֹמֵר לוֹ. גּוֹפְיָנוֹ מִלְּמַעֲלָן. HALAKHAH: “If the ground floor and the upper floor,” etc. But if the owner of the ground floor wants to build and the owner of the upper floor does not, may he tell him: seal it?²⁸Can the ground floor dweller ask the owner of the upper floor to provide a roof? If both floors were rebuilt, the roof would be a charge on the second floor’s owner. Let us hear from the following: ²⁹A related baraita is Tosephta 11:4.“If his collapsed building was next to another’s collapsed building³⁰And the two buildings shared a wall., and he rebuilt without permission, he computes his actual expenses and he has to pay him all his expenses³¹If the second owner later decides to rebuild his house, he cannot use the other building’s wall without paying the first builder’s cost in full. But at the moment of building, he is not required to contribute..” This implies that he cannot tell him, seal it on the side. Just as he cannot tell him, seal it on the side, so he cannot tell him, seal it on top³²The owner of the ground floor has no regress on the owner of the upper floor at the moment when he is building; he has to finish his own roof. He will be able to recoup part of his expenses only when the owner of the upper floor decides to rebuild..