The Talmud discusses a house that is less than ten tefachim high on the interior, and thus insufficient to qualify as a private domain; this can be remedied by digging out a space (4X4 amot) that completes the measurement. This space can be anywhere in the room, and the rest of the room aquires the status of private domain as “Chorei Reshut ha'Yachid” [holes coming out from a private domain].

The Tosafot inquire as to why this differs from a comparable situation with a sukkah; in that case, the new space that is created must be within three tefachim of the walls. They answer that the case of sukkah is different, in that what is required is the establishment of walls next to the schach; thus, the carved out space must be joined to the wall, and thus must be within three tefachim to do so. As further noted in the Tosafot Yeshanim, in the Shabbat case there is a wall that is ten tefachim high, on the outside; the only issue is having that measurement of space on the inside, and the carved out area accomplishes that. The Rosh (#11) combines the two points, and asserts that in the case of sukkah, the issue is the requirement of walls next to the schach. In the case of Shabbat, the need is for the area to be protected by the walls, which can be done from afar; thus, the outer walls, which are of sufficient height, accomplish this, while the inner walls do not, as the carved out area is too far away to extend them. The Magen Avraham (345:13) accepts the view of the Rosh practically, and writes that if the outer walls are less than ten tefachim, the above scenario does not help even in the case of Shabbat (see also R. Shmuel Rozovsky, Zikhron Shmuel, 26:2).