The Construction of a Sukkah

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The laws of sukkah have numerous leniencies that allow for the construction of a sukkah that is not completely enclosed.  In this issue, we will explore some of those leniencies and provide some practical applications.

The Basic Construct of the Sukkah

The Mishna, Sukkah 2a, states that a sukkah requires three walls.  The Gemara, Sukkah 6b, quotes a Beraita that in reality, it is sufficient to have only two whole walls and the third wall may be one tefach (approximately 3.15-3.78 in.) wide.  The conclusion of the Gemara, Sukkah 7a, is that if one wants to construct a shorter third wall, that side must have a tzurat hapetach (a representative door frame) spanning the length of the third side.  This means that there is a post on each side and a beam on top of the posts.  [See Rama (1520-1572), Orach Chaim 630:2 and R. Yisrael M Kagan (1838-1933), Mishna Berurah 630:13, regarding the use of the schach as the top post.]  Furthermore, one should use a board slightly bigger than a tefach and place it slightly less than three tefachim from the corner to create a wall of four tefachim. [See figure 1.]

The Gemara also distinguishes between a sukkah whose two whole walls are adjacent and a sukkah whose two walls are opposite each other.  If the two walls are adjacent, a tefach is sufficient on the third wall if there is a tzurat hapetach.  If the two walls are opposite each other, the third wall must span seven tefachim, which can be accomplished by placing a board slightly bigger than four tefachim within three tefachim of the corner. [See figure 2.] Rambam (1135-1204), Hilchot Sukkah 4:3, requires a tzurat hapetach for the wall of seven tefachim and Rabbeinu Asher (c. 1250-1328), Sukkah 1:6, does not require it.

The Concept of Lavud

There is a concept known as lavud that treats gaps of less than three tefachim as if they are enclosed.  This is why a board that is slightly bigger than one tefach can be placed within three tefachim of the corner to create a four tefach wall.  The same applies to the four tefach board that creates a seven tefach wall.

Tosafot, Sukkah 16b, s.v. B'Fachot), note that one cannot create a wall completely based on lavud.   Therefore, one cannot construct walls of vertical or horizontal strips within three tefachim of each other.  [See figure 3.]  In order to construct a valid wall, the wall must extend horizontally and vertically across the required length and width of the wall.  R. Avraham Gombiner (c. 1633-1683) Magen Avraham 630:1, understands that the opinion of Tosafot is that one can only create walls of vertical or horizontal strips if the strips enclose four walls.  Mishna Berurah, 630:7, codifies the opinion of Tosafot as understood by Magen Avraham.  Nevertheless, Mishna Berurah, Sha'ar HaTziyun 630:49, does allow vertical or horizontal strips on a three-walled sukkah when there are other mitigating factors.

Gud Asik: Projecting the Walls Upward

The Gemara, Sukkah 4b, cites a Beraita that records a dispute as to whether one can build a sukkah without walls on the top of a flat roof.  There is further dispute in the Gemara whether the Beraita is dealing with a case where the schach extends across the entire roof and the walls of the house are aligned with the schach [see figure 4] or whether the Beraita is dealing with a case where the schach is not aligned with the walls of the house. [See figure 5.]

Rambam, Hilchot Sukkah 4:11, rules that if the schach is aligned with the walls of the house, the sukkah is valid.  If the schach is not aligned with the walls of the house, the sukkah is invalid.  Rabbeinu Asher, Sukkah 1:6, rules that in either case, the sukkah is invalid.  R. Yosef Karo (1488-1575), Shulchan Aruch, Orach Chaim 630:6, quotes both opinions but seems to side with the opinion of Rabbeinu Asher.

The Gemara states that the basis for allowing a sukkah that has no walls at the edge of the roof is the principle of gud asik mechitzta (the wall extends upwards).  Therefore, the walls of the house extend upwards to create the walls of the sukkah.  As such, those who do not accept the validity of such a sukkah seem to reject the application of gud asik mechitzta to the laws of sukkah.  Yet, the Mishna, Sukkah 16a, states that the walls do not have to extend all the way up to the schach.  It is sufficient if the walls are ten tefachim high.  If one does not apply gud asik mechitzta to the laws of sukkah, how does one explain why a sukkah does not require walls that extend to the schach?

R. Ya'akov Yisrael Kanievski (1899-1985), Kehillot Ya'akov, Sukkah no. 4, explains that there are two ways to understand why a sukkah does not require walls that reach the schach.  First, the principle of gud asik mechitzta projects the walls up to the schach.  Second, there is no requirement for the walls of the sukkah to reach the schach.  The walls of the sukkah don't need to enclose the sukkah, but rather to demarcate the sukkah.  As long as the sukkah contains three walls of ten tefachim, they are effective in demarcating the sukkah.

R. Ya'akov ben Asher (1269-1343), Tur, Orach Chaim no. 630 and Shulchan Aruch, Orach Chaim 630:9, rule that if the walls are not directly under the schach but are within three tefachim of the schach, the sukkah is valid, even in a situation where the walls are only ten tefachim tall. [See figure 6.] R. Akiva Eger (1761-1837), in his responsa (no. 12) questions this ruling.  He infers from a comment of Rabbeinu Nissim (1320-1380), Sukkah 9a, that one cannot combine the concept of lavud with another leniency.  As such, one cannot project the walls vertically using gud asik mechitzta and then project them horizontally using lavud.  R. Kanievski notes that one can resolve the leniency to allow a ten tefach wall that is not directly under the schach by asserting that allowance of a ten tefach wall is not based on gud asik mechitzta, but rather on the lack of a requirement for the sukkah walls to enclose the sukkah.  There is no special leniency allowing a ten tefach wall and therefore, lavud may be applied.

Dofen Akuma: The Bent Wall

The Mishna, Sukkah 17a, states that if there is a hole in the roof of a house, one may place schach on the hole and use it as a sukkah provided that there are less than four amot (approximately 75.6- 90.72 in.) from the walls of the house to the hole. [See figure 7.] The Gemara, Sukkah 4a, states that the Mishna is based on the principle of dofen akumah (crooked wall) that allows us to view the ceiling of the house as part of the wall.

Rabbeinu Nissim, Sukkah 2a, s.v. Banah, explains that the principle of dofen akumah is that we view the wall and the ceiling as one unit that is bent towards the schach.  Based on this explanation, Rabbeinu Nissim contends that this principle is only applicable if the wall extends up to the ceiling. If there is a gap between the wall and the ceiling, one cannot apply dofen akumah. [See figure 8.]  R. Yosef Karo, Beit Yosef, Orach Chaim no. 632, notes that Tur, Orach Chaim no. 632 has a different understanding of dofen akumah.  According to Tur, we view the ceiling as an extension of the schach.  R. Karo notes that although Tur agrees with Rabbeinu Nissim that one may not fulfill the mitzvah sitting under the ceiling portion, Tur will disagree and maintain that dofen akumah is valid even if the wall does not extend to the ceiling.  Magen Avraham 632:1, codifies the opinion of Rabbeinu Nissim.  R. David HaLevi Segal (c.1586-1667), Taz, Orach Chaim 632:1, codifies the opinion of Tur.

A more common scenario relevant to this discussion is the case of an overhang that is above the level of the schach. [See figure 9.]  R. Meir Eisenstat (1670-1744), Panim Me'irot rules that Rabbeinu Nissim would not apply dofen akumah and one should not count that wall as one of the walls.  Mishna Berurah, Bei'ur Halacha 632:1 cites R. Eisenstat's comments.  R. Avraham D. Wahrman (1771-1840), Eshel Avraham no. 632, contends that as long as the wall extends to the schach, Rabbeinu Nissim will apply dofen akumah, even if the overhang is above the level of the schach.