The Walls of the Sukka

  • Rav David Brofsky

A Wall that Cannot Withstand a Ruach Metzuya – Canvas Sukkot


The Mishna (12a) teaches that “all materials are valid for the walls.” Indeed, throughout the masekhet, the gemara describes constructing walls from materials which one cannot use for sekhakh (2a, 21b, 23a, 24b).  Interestingly, the Or Zaru’a (Hilkhot sukka 289:2; see also Hagahot Asheri 1:24) cites a Yerushalmi which warns that one may not construct a sukka from materials which are mekabel tum’a (objects which potentially may become impure), i.e. materials which may not be used for sekhakh.  This position is troubling, not only because that gemara consistently implies that one may use objects which are mekabel tum’a for walls, but also because the Yerushalmi itself (1:6) implies the opposite!


The Rishonim, and the Shulchan Arukh (630:1) rule that one may construct the walls of a sukka from any material.  Although the Bach suggests that one should refrain from constructing the walls from materials which one may not use for sekhakh, the Acharonim reject this stringency.

As mentioned above, one may use any material for constructing the walls of the sukka.  The Talmud even discusses scenarios in which one may use an animal (sukka 23a), or even one’s friend (Eruvin 44a-b) as a wall.

Although the Talmud permits one to construct the walls of the sukka from any material, the gemara establishes certain limitations to this principle.  For example, the Gemara (24a) teaches that the walls of the sukka must be able to withstand a common wind (ruach metsuyah) without moving.


If he makes his sukka between trees, so that the trees form its walls, it is valid.  R. Acha b. Yaakov said, “A partition which is unable to withstand a normal wind is not a valid partition.  Haven’t we learned, “if he makes his sukka between trees, so that the trees form its walls, it is valid.” But do [the trees] do not sway to and fro? — We are dealing here with solid [trees].  But are there not the swaying branches? — [It refers to] where he plaited it with shrubbery and bay-trees. 


The gemara describes how one may use trees as the walls for one’s sukka, as long as the trees are solid and firmly rooted, and the branches are tied down.  Apparently, R. Acha b. Yaakov understands that although the wind will not knock down the walls of the sukka, walls that move cannot be considered halakhically valid walls (Sha’ar Ha-Tziyun 45). 


How much must the walls move in order to be disqualified? Furthermore, what is the basis for this halakha?


Some (Chazon Ish, Hilkhot Eruvin 13:6) suggest that a mechitza that cannot withstand a ruach metzuya is not valid only when the walls move in a fashion which disqualifies them as walls, i.e.  they fall, or they sway more than three tefachim in either direction.  Earlier authorities, such as R. Moshe di Trani (1505-1585, known as the Mabit) in his Kiryat Sefer (Hilkhot Sukka, Chapter 4), agree.  According to this approach, one should be permitted to construct a sukka in an area without wind.  Indeed, the Be’er Heitev (630:10) cites those who permit building a sukka from thin sheets in a courtyard surrounded by walls.  The Chazon Ish (OC 52:14) is inclined to agree with this conclusion.


Others disagree, and understand that a wall which can be swayed by the wind is simply not considered a halakhically valid wall.  Many Rishonim (see Ritva, sukka 24b s.v. amar, for example) explain that even if the wind moves the walls, without causing it them to fall, they are disqualified.  Some bring a proof from the following gemara (22b):


If one erects his sukka on the top of a wagon, or on the deck of a ship, it is valid.  According to whom is our Mishna? According to R. Akiva, as it has been taught, He who erects his sukka on the deck of a ship, R. Gamaliel declares it invalid and R. Akiva valid.  It happened with R. Gamaliel and R. Akiva when they were journeying on a ship that R. Akiva arose and erected a sukka on the deck of the ship.  On the morrow the wind blew and tore it away.  R. Gamaliel said to him, “Akiva, where is your sukka? Abayye said, “All are in accord that where it is unable to withstand a normal land breeze it is nothing; if it can withstand an unusually [strong] land breeze, all are in accord that it is valid.  Where do they dispute? Where it can withstand a normal land breeze, but not a normal sea breeze; R. Gamaliel is of the opinion that the sukka must be a permanent abode, and since it cannot withstand a normal sea breeze, it is nothing, while R. Akiva is of the opinion that the sukka must be a temporary abode, and since it can withstand a normal land breeze, it is valid.


According to this passage, R. Akiva erected the sukka on the ship, knowing that a normal sea breeze might topple his sukka.  In other words, he did not refrain from building the sukka on the ship, lest it fall.  Rather, apparently whether a wall can withstand a normal land breeze defines whether it is a valid mechitza, and therefore even if one builds a sukka that can withstand a normal land breeze in a place with a stronger breeze, which is likely to topple the sukka, the sukka is still valid. 


            If the strength of the walls, and not whether practically they will or will not sway in the wind, determines the validity of a sukka, then even if a sukka which cannot withstand a ruach metuyah is built in an enclosed area, or an area without wind, it should still be invalid, as the mechitzot simply to not qualify as valid walls (Magen Avraham 15).


            R. Aryeh Pomeranzyck (Emek Beracha, sukka, 19) and R. Tzvi Pesach Frank (Mikraei Kodesh, sukka 1:2) discuss this issue in depth, as does R.  Moshe Feinstein (Iggerot Moshe, OC 5:40:2), who explains that this law based is upon the principle of teshvu ke-ein taduru -- one’s sukka should be like one’s house, which does not sway in the wind. 


The Shulchan Arukh 630:10 rules in accordance with the gemara cited above:


One who makes is sukka between the trees, so that the trees will form its walls- if [the trees] are strong, or if he tied them and strengthened them so that the wind should not constantly move them… [this sukka] is valid.


            Therefore, one should not eat or sleep in a sukka whose walls sway.  While the Chazon Ish identifies three tefachim as the amount of swaying which invalidates a sukka, R. Ovadya Yosef (Yechavveh Da’at 3:46) insists that any sawing disqualifies the sukka.  R. Moshe Feinstein (Iggerot Moshe OC 5:40:2) writes that slight swaying (nidnud ketzat) may not disqualify the sukka. 


In addition to fearing that the walls may sway in the wind, the Tur (630), citing Rabbeinu Peretz, raises another concern. 


It is improper to make the walls from sheets of flax...  even if he tied them securely [because] sometimes they become unfastened, without his being aware, and the result is a wall that does not stand in the wind.


Rabbeinu Perets rules that one should not even use walls made from sheets if they are tied down, lest they will become detached.  Rabbeinu Peretz apparently did not consider these sheets to be inherently not valid to serve as walls for the sukka, but rather he is concerned that they may become unfastened.  The Shulchan Arukh (630:10) cites this view.  Therefore, although this restriction is not recorded in the gemara, normative practice prohibits making the walls of the sukka from sheets, lest they become unfastened. 


Many contemporary authorities note the popularity of sukkot constructed from canvas, or at times, plastic walls.  Seemingly, according to what we learned above, even if the walls do not sway in the wind, one should still refrain from constructing a sukka from sheets.  R. Moshe Sternbuch, for example, in his Mo’adim U-Zemanim (1:84) explains that in his view slight movement of the walls does not pose a problem, and therefore if one secures the sheet tightly, all around the frame, then the sukka is valid.  He still insists that one should preferably not rely upon this, as does R. Moshe Feinstein (OC 5:40:2), who notes that this leniency doesn’t appear in any of the commentaries on the Shulchan Arukh.  Some suggest that if the canvas walls are attached tightly, and fitted with metal rings, that there is no fear that they will become detached, then they may be used (Sukka Ke-Hilkhata Chapter 4, note 2; Cheiko Mamtakim, 630:42).  Although reasonable, one might still insist that the Shulchan Arukh intended to discourage the use of a fabric for sukka walls in all cases.  R. Moshe Feinstein (ibid.) writes that one should not misinterpret the availability of canvas sukkot as an endorsement of their validity.  Interestingly, it is worth noting that the Arukh Ha-Shulchan (530:32) writes that be-diavad, if one tied the canvas walls, the sukka is valid.


In recent years, the practice of using horizontal poles, or tightly strung strings, and relying upon the halakha of lavud, has gained great popularity.  As long as there are no uninterrupted gaps of more than three tefachim, for a height of ten tefachim, the walls of the sukka are valid, even though the majority of space is not filled with solid matter.  Therefore, assuming that three tefachim is, minimally, 24 cm, and ten tefachim is between 80–100 cm, then one should place a horizontal pole or string at approximately 24 cm intervals, until three “walls” of 80-100 cm are constructed.  The Shulchan Arukh even mentions this practice, which originally appeared in the Hagahot Rabbeinu Peretz to the Semak.  He writes that “One who wishes to make [his walls with] sheets, should preferably weave mechitzot of reeds, less than three tefachim apart.”


This practice is also relevant for those who construct sukkot on their balconies, often using the picketed balcony as the walls.


            Not all agree that one can construct a sukka from horizontal strings within three tefachim of one another.  The Magen Avraham (630; see also Mishna Berura 7), based upon the view of Tosafot (sukka 16b, s.v. be-fachot), writes that unless one encloses the entire sukka, i.e. all four walls, with these walls, one cannot rely upon lavud for all three walls of one’s sukka.  The Eliyah Rabbah (19) writes that one should not be concerned with their view in our case, as the true halakhic wall, in our case, is the canvas wall, and the lavud wall is added as a stringency (see also Sha’ar Ha-Tziyun 49). 


Supporting the Sekhakh on a Davar Ha-Mekabel Tum’a


            The walls of the sukka serve two functions: First and foremost, they are the mechitzot of the sukka.  As we discussed last week, a sukka must be constructed of at least three walls, or two walls and a piece.  Secondly, the walls may (although not necessarily) support the sekhakh, which must cover the entire sukka.  In this second context, the Mishna teaches:


If a man supports his sukka with the legs of a bed, it is valid.  R. Yehuda said, “If it cannot stand by itself, it is invalid.”


Why does R. Yehuda prohibit placing the sukka (i.e. the sekhakh) on the legs of a bed? The gemara continues:


What is the reason of R. Yehuda? — R. Zera and R. Abba b. Mamal disagree.  One says,

“It is because the sukka has no permanence (mipnei she-ein la keva),” and the other says, “It is because he support [the sekhakh] with something which is mekabel tum’a.”


The Rishonim offer different explanations for both interpretations of R. Yehuda, and, as we shall see, differ regarding the final halakha.


            Why does “because the sukka has no permanence” invalidate a sukka resting upon the legs of a bed? In what way does resting the sekhakh on the legs of a bed undermine the permanence of a sukka? The Rishonim offer different interpretations.  Rashi (s.v. she-ein), for example, explains that since the entire sukka rests upon the bed, and is therefore mobile, it lacks “permanence”.  Of course, some Rishonim (see Tosafot s.v. she-ein) question how his case differs from a sukka resting on a boat or a wagon (22b), which are also mobile! The Ra’avad (Hasagot Ha-Ra’avad, 10a) adopts an opposite interpretation: This sukka lacks “permanence”- because if the bed is moved the sukka will collapse. 


Why would R. Yehuda not permit one to support the sekhakh on something which is mekabel tum’a? Rashi (s.v. she-ma’amidah) explains:


Even though we only learned this disqualification regarding sekhakh, since [the ma'amid] supports the sekhakh, it is as if he used that which is mekabek tum’a for sekhakh.


Rashi implies that by supporting the sekhakh with an object which is mekbel tum’a, it is as if this object was used as the sekhakh.  This interpretation is difficult, not only because he implies that this is a problem mi-de’oraita, but also because he views that which supports, or enables, as the part of that which is supported or enabled itself!


            Other Rishonim (Ra’avad, 10a; Ritva s.v. ve-chad; Ran s.v. matnitin) explain, simply, that the Rabbis prohibited placing sekhakh upon a davar she-mekabel tum’a lest one come to use this material as sekhakh.  Some question what the difference is between placing sekhakh upon the legs of a bed, and constructing a sukka on the top of a tree, which is also invalid for sekhakh! The Ra’avad (Hasagot Ha-Ra’avad 10a) suggests that since it is uncommon to use trees, which are attached to the ground and annot be used as sekhakh, when building a sukka, the Rabbis saw no reason to prohibit “ma’amid” (supporting) on a tree.  Alternatively, the Ramban (Milchamot, 10a) notes that the Rabbis prohibited supporting sekhakh on a material which is invalid for sekhakh; one who builds a sukka in a treetop, however, doesn’t place the sekhakh on the tree, but rather rests the sukka on the tree. 


            The Rishonim differ as to whether the halakha follows the first opinion of the mishna, the Chachamim, who permit supporting a sukka on the leg of a bed, or R. Yehuda.  Furthermore, even if the halakha follows the opinion of R.  Yehuda, is that because such a sukka lacks permanence, or because the sekhakh rests upon a material which is mekabel tum’a. 


The Rambam (see Commentary to the Mishna, and note his omission of this halakha in the Mishnah Torah), Ba’al Ha-Ma’or (10a), Ra’avya (631), Maharil (Responsa 83), and others rule like the Chakhamim.  Other Rishonim rule in accordance with R. Yehuda.  However, while the Rosh (1:1) accepts the opinion which explains that R. Yehuda requires that the sukka have “permanence," the Ramban (Milchamot, 10a), and many other Rishonim, rules that one may not rest the sekhakh upon a davar she-mekabel tum’a. 


Interestingly, the Shulchan Arukh appears to rule like the Chakhamim, as he validates a sukka resting upon the legs of a bed (630:3).  On the other hand, elsewhere (629:7) he explicitly expresses doubt whether one may use a ladder, which is mekabel tum’a, to support the sekhakh. 


The Acharonim disagree as to how to understand this doubt of the Shulchan Arukh.  On the one hand, the Taz (10) explains that a ladder is not valid for sekhakh, because it is more than four tefachim wide, and the Rabbis prohibited using boards more than four tefachim wide (sukka 14a)  Therefore, the Shulchan Arukh feared that one might confuse using this ladder to support sekhakh, and using this actual ladder as sekhakh.  On the other hand, other Acharonim, including the Magen Avraham, Shulchan Arukh Ha-Rav and the Chayye Adam insist that the Shulchan Arukh is expressing his concern that it may be prohibited to support sekhakh on a material which is mekabel tum’a.


The Arukh Ha-Shulchan (629:19) asserts that the halakha is in accordance with the lenient opinion, and that one should follow the opinion which is not concerned with supporting sekhakh upon a material which is mekabel tum’a.  The Mishna Berura (630:59; see also Sha’ar Ha-Tziyun 60), however, writes that although the law is really in accordance with the more lenient opinion, one should preferably act stringently regarding this matter. 

            Interestingly, the Shulchan Arukh implies that all agree that one may rest the sekhakh upon a material which is not mekabel tum’a, which is supported by a material which is mekabel tum’a – known as ma’amid de-ma’amid.  The Shulchan Arukh (629:8) permits one to attach the wooden beams of the sukka with metal nails, which are mekabel tum’a.  Many Acharonim (see Mishna Berura 629:26, and Sha’ar Ha-Tziyun 51) understand that even those who are stringent regarding ma’amid al davar she-mekabel tum’a, certainly permit one to place sekhakh on materials which are not mekabel tum’a, which are supported by material which is mekabel tum’a.  Chazon Ish (143:2) disagrees, and to this day his student use only wooden pegs, which are not mekabel tum’a, in constructing the sukka. 


In practice, it is customary not to be concerned with ma’amid de-ma’amid, and to construct sukkot with metal frames.  However, many avoid placing sekhakh directly upon materials which are mekabel tume-ah.  Rather, they place wooden beams above the metal horizontal beams of the frame, and place the sekhakh onto the wooden beams. 

Dofen Akuma – Using Part of the Roof as a Wall

            We discussed above the materials and physical viability of the sukka walls, as well as their relationship to the sekhakh.  We will conclude with a brief discussion of a sukka wall comprised of a wall, and part of the roof.  The Mishna (17) teaches:

If [the roof of] a house is breached, and he placed a sukka-covering over it, if there is a distance of four cubits from the wall to the covering, it is invalid. 

The Mishna describes a case in which the middle of a roof is breached.  The person wishes to put sekhakh over the hole, and rely upon the walls of the house to function as the walls of the sukka.  Part of the roof, however, still extends from the walls of the house until where the sekhakh begins.  The Mishna teaches that if the part of the roof is wider than four amot, then the walls of the house cannot be relied upon.  However, if the part of the remaining roof is narrower than four amot, then the sukka is valid.  The Gemara (4a, 17a) bases this upon the principle of dofen akuma (literally, a bent wall).  The Rishonim offer different explanations for this principle.

Rashi (s.v. pesulah) cites two understandings.  He first suggests that the wall and the roof combine, and the end of the roof constitutes the meeting place of the wall and the sekhakh.  This is only possibly, he claim where there is sekhakh pasuk at the edge of the roof, as sekhakh pasuk can combine and join the wall.  Air, however, cannot become part of the wall, and therefore it invalidates the sukka if there is a gap of three tefachim between the wall and the sekhakh.  He then suggests, but rejects, the possibility that we view the wall as slanting, at a diagonal angle, towards the sekhakh.  In this image, the wall is moved closer to the sekhakh, but the sekhakh pasul remains sekhakh pasul.

            The gemara (4a) earlier in the masekhet offers a different application of dofen akuma. 

If it was higher than twenty amot...  If [he built the ledge] on a side [wall] — if from the edge of the ledge to the wall [opposite] there are four amot it is invalid; but if the distance was less than four cubits, it is valid.  What principle does he teach us by this ruling? That we apply the rule of dofen akuma (the ‘curved wall’)? But have we not [already] learnt it: A house [the middle of whose flat roof] is missing and one placed the valid covering of a sukka upon it, if there are four cubits from the [top of the] wall to the covering, it is invalid; which [shows that] if the distance was less than this it is valid? — One might have thought that only there [it is valid] since [each side] is suitable [to serve] as a wall; but that here since it is unsuitable for a wall, one might say that it is invalid, [therefore] we were taught [that even here the principle is applied].

In this case, a sukka was built, improperly, over twenty amot high.  In an attempt to salvage part of the sukka, he builds a platform along the corner-edge of the sukka, in which case the distance between the sekhakh and the elevated platform is less than twenty amot.  However, only two of the walls join the platform to the sekhakh.  In order to validate the sukka, he needs to somehow make use of the opposite, third wall.  The gemara teaches that if the opposite wall is within four amot of the platform, one may apply the principle of dofen akuma.

            Rashi (s.v. pachot) explains that we view the sekhakh raised above twenty amot as a continuation of the wall, bent at a right angle.  In other words, the roof becomes an extension of the wall, meeting the sekhakh at a distance of less than four amot. 

The Ritva (4a) brings another interpretation.  He cites an opinion of Rashi, found in other Rishonim (Ran 2a; Maggid Mishna 4:14), but not in our printed Talmud.  Rashi explains that that the opposite wall is bent, diagonally, towards the platform.  In this case, the opposite wall joins the sekhakh kasher and the entire sukka becomes valid.  He adds that according to this interpretation, one may even sit under the sekhakh which is above twenty amot, as it is simply considered sekhakh pasul within a valid sukka! This opinion, of course, is similar to the opinion Rashi rejected previously (4a).  The Ritva then cites another interpretation, attributed to Tosafot, which is similar to Rashi found in our gemara. 

            Interestingly, the Rambam describes the principle of dofen akuma differently when citing these different cases.  Regarding the case in which the sukka was built over twenty amot height (sukka 41), he writes (Hilkhot Sukka 4:14):

Should one build the bench in the middle [of the sukka], if there are more than four amot from the edge of the bench to any of the sides [of the sukka], it is not acceptable.  If there are fewer than four amot, it is valid.  It is considered as if the walls touch the bench, and the distance from the bench to the sekhakh is less than twenty amot.

Regarding the case in which the roof of the house was breached (17a), he writes:


Where the substance that is unacceptable as sekhakh is at the side, it disqualifies the sukka if there are four amot of it.  [If there is] less than that, the sukka is valid.  For example, a) [the roof of] a house which was opened in the center and sekhakh placed over the opening b) a courtyard surrounded by an exedra which was covered with sekhakh c) a large sukka over which was placed a substance that was not acceptable as sekhach near the sides of its walls.  [In all these cases,] if there are four amot [or more] from the edge of the kosher sekhakh until the wall, it is not acceptable.  If there is less than that amount, we view it as though the wall has been made crooked – i.e., the substance that is not acceptable as sekhakh is considered part of the wall and it is valid.  This concept is a halakha received by Moshe on Mount Sinai.

In the first case, he describes the walls of the house as if they touch the bench, or platform, similar to the position of Rashi, as cited by the Ritva, or the interpretation Rashi rejected (17a)..  In the second case, he describes how the sekhakh pasul becomes part of the wall, similar to Rashi (17a) and Tosafot. 

            The Rambam seems to accept both understandings of dofen akuma! R. Soloveitchik explains that in the second case, the sekhakh pasul can become part of the wall, a principle received from Moshe at Sinai, and “bend” towards the platform, making one long wall.  However, in the first case, the sekhakh pasul cannot become part of the wall, as it is higher than twenty amot, and therefore it must remain sekhakh pasul.  However, we may view the wall on a diagonal angle, as walls are often bent slightly, first case, and validate the sukka (Reshimot Shiurim, 4a). 

            The Shulchan Arukh (632:1, 633:6-7) cites both cases of dofen akuma.  He rules (632:1) that one should not sleep under the dofen akuma, if it is more than four tefachim in wide.  At times, this principle may be relevant in a semi-enclosed patio.  If the patio is surrounded, on both sides, with two walls, and an overhang, less than four amot hangs off the outer wall of the house over the patio, then one can count the wall of the house as the third wall of the sukka.  In this case, one should merely suspend the sekhakh over the patio, and the sukka is valid, even if the fourth, outer “wall” is open.