Yerushalmi Bava Metzia 10:2 ירושלמי בבא מציעא י׳:ב׳

MISHNAH: The ground floor and the upper floor belong to two different persons¹⁶Following the Babli, Maimonides and Rashi explain that the house is the property of the person dwelling in the lower apartment; the dweller in the first floor rented his apartment. The landlord is required to keep the rented apartment in good repair. According to Tosaphot, the Mishnah either refers to a rental situation or to two brothers who inherited the house together. Then the expenses for necessary repairs have to be borne equally by both of them. If one of them refuses to pay his part, the other brother may use his apartment as a temporary dwelling.; if the upper floor sprang a leak and the owner of the ground floor does not want to fix it, the owner of the upper floor descends and dwells below until he fixes the upper floor for him. Rebbi Yose says, the lower one gives the roofing¹⁷Wooden logs or planks to make a roof. and the upper one the roof covering¹⁸Mortar and cement to make a smooth, watertight surface..

HALAKHAH: “The ground floor and the upper floor belong to two different persons,” etc. It was stated: “If it sprang a leak above the oven, he descends. If it sprang a leak above the fireplace, he descends¹⁹Not to dwell there but to bake and cook in the courtyard in front of the bottom dweller’s door. In the Babli, 116b, this is Rav’s opinion. Samuel holds that if the top dweller has to descend for any household chores, he comes to live in the ground floor apartment..” But he may tell him, make yourself a ladder so you do not have to ascend and descend through my dwelling²⁰In any case the second floor dweller is supposed to have his own stairs outside the first floor dweller’s apartment..

“Rebbi Yose says, the lower one contributes the roofing and the upper one the roof covering,” etc. ²¹Babli 117a. In most mss. of the Babli the name is Justinus. Rebbi Justus in the name of Rebbi Simeon ben Laqish:: The bottom dweller contributes the logs and the planks²²The logs to make a roof and the planks to create a platform on top of the roof.; the dweller on the upper floor contributes the roof covering¹⁸Mortar and cement to make a smooth, watertight surface.. Which kind of roof covering? Rebbi Jacob bar Aḥa in the name of Rebbi Eleazar: heavy roof covering. Rebbi Abbahu in the name of Rebbi Eleazar: medium roof covering, since they only spoke about rinsing cups. But if he wanted to wash clothing, also Rebbi Abbahu in the name of Rebbi Eleazar will agree that the roof covering has to be heavy²³If the flat roof is used for any activity, the roof covering must withstand prolonged use without becoming leaky.. Rebbi Ḥanina instructed those of Sepphoris that both of them should contribute the logs and the plates since they expect to bring up there their wine and their produce²⁴If both parties intend to use the roof, both have to equally share the expenses..