Reference for Bava Batra 119:4
<big><strong>מתני׳</strong></big> לא יפתח אדם לחצר השותפין פתח כנגד פתח וחלון כנגד חלון היה קטן לא יעשנו גדול אחד לא יעשנו שנים אבל פותח הוא לרה"ר פתח כנגד פתח וחלון כנגד חלון היה קטן עושה אותו גדול ואחד עושה אותו שנים:
Look then at the following clause: HE MAY IF HE PLEASES BUILD AN INNER CHAMBER IN HIS HOUSE AND THEN BUILD AN UPPER CHAMBER OVER HIS HOUSE AND MAKE THE ENTRANCE FROM THE HOUSE. Will not this also bring more people through the courtyard? — R. Huna said: When it says here [that he builds] a room, It means that he divides one of his rooms into two, and when it says [that he builds] an upper chamber, it means that he makes a balcony.<span class="x" onmousemove="('comment',' And though he thus obtains additional rooms for letting. he is perfectly within his rights. ');"><sup>3</sup></span>