Bava Batra 6B

בבירה גדולה, משתמש בזיזיה ובכתליה עד ארבע אמות, ובעובי הכותל ⁠– במקום שנהגו, אבל בתרבץ אפדני ⁠– לא. ורב נחמן דידיה אמר: אפילו בתרבץ אפדני, אבל רחבה שאחורי הבתים ⁠– לא. ורבא אמר: אפילו רחבה שאחורי הבתים.

in a large building with many residences, the renter may make use of the building’s projections and of the cavities in its external walls up to a distance of 4 cubits from his room, and he may make use of the thickness of the wall in a place where it is customary to do so. But as for making use of the building’s front garden [betarbatz], he may not do so. And Rav Naḥman himself said: He may make use of even the building’s front garden. But he may not use the yard that is at the back of the house. And Rava said: He may use even the yard that is at the back of the house.

אמר רבינא: האי כשורא דמטללתא, עד תלתין יומין ⁠– לא הוי חזקה, בתר תלתין יומין ⁠– הוי חזקה. ואי סוכה דמצוה היא, עד שבעה יומין ⁠– לא הוי חזקה, בתר שבעה יומין ⁠– הוי חזקה. ואי חבריה בטינא ⁠– לאלתר הוי חזקה.

Apropos the use of a wall between neighbors, Ravina says: If one’s beam supporting a covering for shade was resting on his neighbor’s wall for up to 30 days, there is no acquired privilege for him to continue using it, since the neighbor can claim that he had assumed that the beam was there only temporarily and for that reason he did not protest. But after 30 days, there is an acquired privilege. And if it was for a sukka that was being used for the mitzva on the festival of Sukkot, for up to 7 days there is no acquired privilege for him to continue using it, since it is assumed that it is there for the mitzva and that after the Festival it will be removed. But if after 7 days the neighbor did not protest, there is an acquired privilege for him to continue using it. And if the one using the beam attached it with clay, there is immediately such an acquired privilege.