Last year, I received a frantic call the day before Sukkot. The query came from neighbors who while busily erecting their sukkah. They needed to know: “Can we use zip ties to hold down our sekhakh? We read in the OU guide at shul that it’s not allowed!” The halakhic recommendations prepared by Rabbi Eli Gersten and reviewed by Rabbi Yaakov Luban in 2013 include the following questions and answers that would seem to prohibit the use of plastic zip-ties:
Q: How should the schach be supported?
A: One should not rest schach directly on metal or plastic, but rather on wooden beams placed on top of the metal poles (Shulchan Aruch Orach Chaim 629:7). If one’s mats are woven with plastic wire, they must make sure that the schach is placed perpendicular to the wooden beams; otherwise the stalks are being supported exclusively by the plastic wire.
Q: Can one tie their schach mats to the sukkah with string?
A: Schach mats are notorious for blowing off of the sukkah. Therefore, the mats should be tied down. However, one should not tie the schach with wire or synthetic strings, but rather they should use cotton or hemp string or place heavy 2x4s on top of the schach to weigh it down.”
To my mind, there’s more to this matter. A thorough analysis of the parallel sugyot in both talmuds (m. Sukkah 2:2, y. Sukkah 52d (2:2), b. Sukkah 21b), as well as the attendant commentaries, offers an alternate take on the halakhic sources in defense of the more lenient practice, that it is allowed (even ab initio) to use zip-ties, and even metal wire to support the sekhakh of the sukkah.
In yeshiva shorthand, this issue is known as “maamid be-davar ha-mekabbel tumah,” that is, the question of the permissibility of supporting the sekhakh of the sukkah with a material (like metal) that is susceptible totumah (impurity). Or more broadly, a material (like plastic) that is unsuitable to be used as sekhakh. Besides the recommendations published by the OU, this Halakhah (among the numerous laws of the walls and roof of thesukkah) has become well-known, and is taken seriously (perhaps disproportionately seriously) by many Halakhah-abiding Jews.
Sekhakh for the sukkah is limited by several criteria (Rambam Hil. Sukkah 5:1, Shulhan Arukh, Orah Hayyim 629:1): the material must have grown from the ground (גדולו מן הארץ), must be detached from the ground (נעקר מן הארץ), and it must be not be susceptible to impurity (אינו מקבל טומאה) e.g. it cannot be food or any utensil (like a bowl or bed).
The Mishnah (m. Sukkah 2:2) presents a debate relevant to this issue between the anonymous first opinion in the Mishnah, that of the Sages, and Rabbi Yehudah:
הסומך סוכתו בכרעי המטה כשרה. רבי יהודה אומר: אם אינה יכולה לעמוד בפני עצמה פסולה.
One who leans his sukkah on bed-poles—it is suitable. Rabbi Yehudah rules: If it cannot stand on its own [i.e., without the bed-poles]—it is disqualified.
The Talmud Bavli (b. Sukkah 21b) expands and clarifies this debate between the Sages and Rabbi Yehudah, specifically explaining how it articulates legal principles applicable beyond the case of a sukkah built into bed-poles:
מאי טעמא דרבי יהודה? פליגי בה רבי זירא ורבי אבא בר ממל. חד אמר: מפני שאין לה קבע, וחד אמר: מפני שמעמידה בדבר המקבל טומאה. מאי בינייהו? כגון שנעץ שפודין של ברזל וסיכך עליהם. למאן דאמר לפי שאין לה קבע, הרי יש לה קבע; ומאן דאמר מפני שמעמידה בדבר המקבל טומאה, הרי מעמידה בדבר המקבל טומאה. אמר אביי: לא שנו אלא סמך, אבל סיכך על גב המטה כשרה. מאי טעמא? למאן דאמר לפי שאין לה קבע, הרי יש לה קבע; למאן דאמר מפני שמעמידה בדבר המקבל טומאה, הרי אין מעמידה בדבר המקבל טומאה.
What is the reason for Rabbi Yehudah’s position? It is a debate of Rabbi Zeira and Rabbi Abba bar Mamal.One [Rabbi Zeira] says it is because it is not “fixed,” and one [Rabbi Abba] says it is because he supports [the sekhakh] with a material which is susceptible to impurity. What [case] distinguishes between the[ir opinions]? Consider for example if he drove metal rods [into the ground] and covered them over [withsekhakh]. According to the one who says [Rabbi Yehudah disqualifies it] because it is not “fixed,” behold this one is “fixed.” And according to the one who says [Rabbi Yehudah disqualifies it] because he supports [the sekhakh] with a material which is susceptible to impurity, behold [here too] he supports [the sekhakh] with a material which is susceptible to impurity [i.e., metal]. Abaye said: They only stated [their opinion] in a case where he leaned [the sukkah against the bed-poles] but if he had covered over a bed [with sekhakh] it would be suitable [even according to Rabbi Yehudah]. What is the reason? According to the one who says [Rabbi Yehudah disqualifies it] because it is not “fixed,” behold this one is “fixed.” And according to the one who says [Rabbi Yehudah disqualifies it] because he supports [the sekhakh] with a material which is susceptible to impurity, behold [here] he does not support [the sekhakh] with a material which is susceptible to impurity.
The sugya as presented here in the Bavli avoids any discussion of the position of the Sages. It also avoids any attempt to prove that the Halakhah follows one opinion or another. The Rishonim, picking up on this lacuna, discuss this question in great detail.
The claim that the sukkah must be “fixed” is talmudic shorthand for a collection of tannaitic debates (collated and discussed on b. Sukkah 7b) about the permanence, sturdiness, and size of the sukkah. Rabbi Yehudah is one of the proponents of this approach (m. Sukkah 1:1 where he allows a sukkah taller than 20 amot), so Rabbi Zeira is justified in seeing that same criterion at play here. Importantly, the opinions who require that the sukkah be fixed are mostly rejected in favor of the opinions allowing or even requiring the sukkah to be עראי—“casual/impermanent.”
Alfasi’s codification (Sukkah 10a, §1010) mirrors the Talmud’s cryptic formulation:
הסומך סוכתו בכרעי המטה כשרה. רבי יהודה אומר: אם אינה יכולה לעמוד בפני עצמה פסולה.
אמר אביי לא שנו אלא סמך, אבל סכך על גבי המטה – כשרה.
One who leans his sukkah on bed-poles—it is suitable. Rabbi Yehudah rules: if it cannot stand on its own—it is disqualified. Abaye said: They only stated [their opinion] in a case where he leaned [the sukkah against the bed-poles] but if he had covered over a bed [with sekhakh] it would be suitable [even according to Rabbi Yehudah].
Alfasi’s goal in writing his code as an abridgement of the talmud text was to make the halakhic conclusions of the sugyot clear; it is surprising to see him quote the Mishnah in full (including the debate) and the statement of Abaye. The reader is left wondering whether Alfasi understood Abaye’s statement to include a conclusive determination according to Rabbi Yehudah, or if Alfasi included it for some other reason.
Three Possible Approaches
There are basically three different approaches on how to rule in this sugya, taking into account both the Talmud and Alfasi’s code—aligned logically along the three different opinions we have seen.
1) We rule like the Sages against Rabbi Yehudah
2) We rule like Rabbi Yehudah, and the reasoning for his ruling is that the sukkah must be fixed, like Rabbi Zeira
3) We rule like Rabbi Yehudah, and the reasoning for his ruling is that the sekhakh must not be supported by a material susceptible to impurity, like Rabbi Abba
The Halakhah follows the Sages: The first approach is taken by Rambam and Rabbi Zerahiah ha-Levi (“Baal ha-Maor”). Rambam expresses his opinion succinctly and clearly in his Commentary to Mishnah (2:2):
ר’ יהודה סובר סוכה דירת קבע בעינן, וכבר נתבארה לך שטתו, ולפיכך מצריך שתהא יכולה לעמוד בפני עצמה … ואין הלכה כר’ יהודה.
Rabbi Yehudah’s opinion is that the sukkah must be fixed and his opinion has already been explained (see Rambam to m. Sukkah 1:1) therefore he requires that it be able to stand on its own … and the Halakhah does not follow Rabbi Yehudah.
This conclusion is corroborated by the fact that Rambam does not address the case discussed in our Mishnah at all in his Mishneh Torah.
Usually, it is reasonable to assume that Rambam and Alfasi agree in their halakhic rulings without strong evidence to the contrary. After all, Rambam praises Alfasi’s code in his introduction to his Commentary to Mishnah as “contain[ing] all the rulings and laws that are needed in our time.” Rambam’s father, Maimon, was a student of Ibn Megas himself a student of Alfasi. However, because Alfasi’s ruling is so cryptic we are still left wondering. For Rambam, our Mishnah itself is enough proof that we rule against Rabbi Yehudah, according to the general rule of mishnaic debates “one against many, the Halakhah follows the many.”
Why then did Alfasi quote the opinion of Abaye—itself a compromise solution that addresses both the interpretations of Rabbi Zeira and the Rabbi Abba bar Mamal—if the Halakhah does not follow the opinion of Rabbi Yehudah at all?
This question is strong enough that Rabbi Zerahiah ha-Levi, a fierce opponent of many of Alfasi’s halakhic rulings, understands Alfasi to have ruled according to Rabbi Yehudah (otherwise why cite Abaye’s conclusion). He sides with Rambam against his understanding of Alfasi, although Rambam likely understood Alfasi to be aligned with his own ruling (see Sefat Emet Sukkah 21b s.v. sham).
The core of this approach lies in two principles 1) that we rule like the majority against Rabbi Yehudah and 2) the reasoning behind Rabbi Yehudah’s ruling may very well be a principle rejected elsewhere in Sukkah. Thus, to reject Rabbi Yehudah’s stringency here is to reject his approach globally, and we never even enter a discussion of supporting the sekhakh with a material susceptible to impurity.
The Halakhah follows Rabbi Zeira within Rabbi Yehudah: The second approach to how to understand the sugya and Alfasi’s ruling is developed by Tosafot (s.v. she-ein) and Rosh (2:1) based on the parallel sugya in the Talmud Yerushalmi. The debate around Rabbi Yehudah’s position as presented in the Yerushalmi takes a much more conclusive turn:
אמר רבי אימי משם שאין ממעי המיטה לסכך עשרה טפחים. אמר רבי [א]בא משם שאין מעמידין על גבי דבר טמא. והא תני ‘מעשה באנשי ירושלם שהיו משלשלין מיטותיהן לפני חלונותיהן והיו מסככין על גביהן.’ אין תימר משם שאין מעמידין על גבי דבר טמא הרי מעמידין על גבי דבר טמא הוי לית טעמא, אלא משם שאין ממעי המיטה לסכך עשרה טפחים.
Rabbi Immi said [the reason behind Rabbi Yehudah’s ruling is] that there are not ten tefahim of space from the surface of the bed to the sekhakh. Rabbi [A]bba said [the reason behind Rabbi Yehudah’s ruling is] that one should not support [the sukkah] on top of something [that can become] tamei. And it was taught [in t. Sukkah 2:3]: ‘A case of people in Jerusalem who used to hang their beds out their windows and cover them with sekhakh.’ If you would say that the reason [for Rabbi Yehudah’s ruling] is that one should not support [the sukkah] on top of something [that can become] tamei, behold they used to support [their sukkot] on top of [beds] which can become tamei, thus that must not be the reason. Rather, it must be that [Rabbi Yehudah disqualifies it] because there are not ten tefahim of space from the surface of the bed to thesekhakh.
This parallel version of sugya presents another version of the debate about the rationale for Rabbi Yehudah’s position that sheds light on our reading of the Bavli. The first explanation of the problem R. Yehudah has with thesukkah, formulated in the Bavli (attributed to Rabbi Zeira) as “it is not fixed,” is explicated in the Yerushalmi (attributed to Rabbi Immi) as about the amount of airspace between the surface of the bed and the sekhakh.
Normally, the ten tefahim of vertical airspace are measured from the floor of the sukkah, disregarding any of the furniture brought into the sukkah; here because the sukkah is built into the bed-poles Rabbi Yehudah’s requirement of fixed-ness (i.e., sturdiness and size) requires that the ten tefahim begin from the top surface of the bed rather than from the floor. Abaye’s solution in the Bavli—building the sukkah around the bed rather than into it—makes perfect sense as to why it would address this concern because once the bed is no longer a part of the sukkah but only a piece of furniture in it, the idea to measure the ten tefahim from the surface of the bed no longer makes sense.
In addition, after recording the debate between Rabbi Immi and Rabbi Abba, the Yerushalmi quotes a proof against Rabbi Abba from the Tosefta; the case of the scrupulous Jerusalemites demonstrates that supporting thesekhakh on top of a bed is not problematic at all. Thus, for the Yerushalmi, within the opinion of Rabbi Yehudah, the correct interpretation must be that of Rabbi Immi and Rabbi Zeira— the problem is that the sukkah is not sufficiently fixed, as it needs ten tefahim from the surface of the bed to the sekhakh.
Rabbi Immi’s interpretation of the case quoted in the Tosefta (that it would be problematic to build a bed-sukkah with air space less than ten tefahim measured from the surface of the bed to the sekhakh) even appears in our text of the Tosefta in situ (though not in the version quoted by the Yerushalmi).
Tosafot and Rosh conclude that the flow of the sugya in both the Yerushalmi and the Bavli (when read as a direct parallel to the Yerushalmi) indicates that the Halakhah follows the opinion of Rabbi Zeira within Rabbi Yehudah. However, if the whole basis of Rabbi Yehudah’s approach is his internally consistent requirement that thesukkah be fixed—an opinion rejected in the Talmud elsewhere—how can the Halakhah accord with him here? Rosh suggests that there are two different standards of fixed-ness.
Although Rabbi Yehudah’s global insistence on a high level of fixedness was rejected by others, in this case, a more minimal standard (that there be ten tefahim from the surface of the bed to the sekhakh) was adopted even by his opponents. Just because the requirement that there be ten tefahim from the surface of the bed to the sekhakh is an example of Rabbi Yehudah’s position on fixed-ness does not mean that it should be rejected here.
The approach of Tosafot and Rosh, corroborated by responsa of Rashba 1:213 (also cited as n.216 of those originally attributed to Ramban) and of Terumat ha-Deshen n.91, is that which was presented by Rabbi Yosef Karo in his Beit Yosef (629 and 630, and see Darkhei Moshe ha-Arokh 629:7) and Shulhan Arukh (Orah Hayyim 630:13) as the conclusive Halakhah:
הסומך סוכתו על כרעי המטה והכרעים הם מחיצות אם יש בה גובה י’ טפחים מן המטה לסכך, כשרה; ואם לאו, פסולה.
One who leans his sukkah on bed-poles, and the bed-poles are walls, if there are ten tefahim from the surface of the bed to the sekhakh, it is suitable. And if not, it is disqualified.
Because the approach of Rosh, based on the case from the Tosefta quoted in the Yerushalmi fundamentally rejects the interpretation of Rabbi Abba (that Rabbi Yehudah’s disqualification is based on a concern of susceptibility to impurity) it follows that Rosh, and seemingly Shulhan Arukh are unconcerned with this criterion. However, fromShulhan Arukh, Orah Hayyim 629:7 it seems like Rabbi Yosef Karo is hedging his ruling to accommodate the stringency of the third approach:
יש להסתפק אם מותר להניח סולם על הגג כדי לסכך על גביו. הגה: לכן אין לסכך עליו; ואפילו להניחו על הסכך להחזיקו, אסור; וה”ה בכל כלי המקבל טומאה, כגון ספסל וכסא שמקבלין טומאת מדרס.
It is doubtful if it is permissible to rest a ladder on the roof in order to cover it over with sekhakh. Rema’s Gloss: Therefore one should not cover it over with sekhakh, and it is even forbidden to place it on top of thesekhakh to secure it, and so too regarding any object that is susceptible to impurity, like a bench or a chair which are susceptible to midras-impurity.
The doubt expressed by Rabbi Yosef Karo, and more fully explicated by Rabbi Moshe Isserles in his gloss, is that the ladder is disqualified because it is susceptible to impurity—a concern that only makes sense within the third approach to our sugya, following the interpretation of Rabbi Abba.
The Halakhah follows Rabbi Abba within Rabbi Yehudah: The third approach to the sugya is developed by Raavad and supported by Ramban and Ran in their commentaries to Alfasi’s code, as they characteristically rebut Rabbi Zerahiah Halevi’s critique. Rabbi Zerahiah ruled in accordance with the Sages, understanding Alfasi to have ruled like Rabbi Yehudah. In response, Raavad and Ramban defend the position of Rabbi Yehudah as interpreted by Rabbi Abba—that it is unsuitable to support the sekhakh on a material that itself can become impure (and perhaps even more broadly, the material supporting the sekhakh must itself be suitable to be used as sekhakh, see Rosh 2:1).
This argument rests on two claims. The first is that the flow of the sugya (involved entirely in a discussion of Rabbi Yehudah’s position) is evidence that the Halakhah follows Rabbi Yehudah, even against the rules followed by Rambam (that is even against the majority opinion of the Sages).
The second claim is that the Halakhah should consider the opinion of Rabbi Abba, not Rabbi Zeira, as authoritative. This is against the conclusion of the sugya as presented in the Yerushalmi, and disregards the proof brought from the Tosefta. Nonetheless, the argument is based on the fact that Rabbi Yehudah’s requirement that the sukkah be “fixed” is rejected elsewhere (cf. b. Sukkah 2a, 3b, 7b).
If Rabbi Yehudah’s position is adopted as authoritative here, it must be for a different reason, namely Rabbi Abba’s rather than Rabbi Zeira’s explanation. (This ignores the clever distinction suggested by Tosafot and Rosh that there is an agreed upon lower standard of fixedness that even Rabbi Yehudah’s opponents concede to him, but again that is based on the Yerushalmi which is not being considered here.)
It is this position—that of Raavad, Ramban, and Ran—that would disqualify a sukkah built where the material supporting the sekhakh is itself susceptible to impurity, like a metal pole or wire. (Synthetic materials are excluded from laws of impurity, but could still be a problem if using any non-valid sekhakh item is prohibited, a possibility Rosh 2:1 refutes.) Because of their characteristic opposition to Rabbi Zerahiah ha-Levi’s interpretations of Alfasi and his halakhic rulings, their defense of the position that he attributed to Alfasi may all be a back-and-forth about a straw-man. Alfasi (and Rambam as explained above) could respond to Rabbi Zerahiah’s critique by saying, “I actually agree with you that the Halakhah follows the Sages against Rabbi Yehudah.”
This would leave Raavad and Ramban’s defense of this position divorced from the actual position of Alfasi. Further frustrating their interpretation is that it does not accord with the material from the Tosefta and Yerushalmi cited by Rosh in support of his interpretation. Nonetheless, because of the prominence of Ramban and Ran in particular (as well as the fact that Rabbi Joel Sirkis in his Bayit Hadash 629 s.v. ‘od strongly endorsed this approach), it entered the halakhic conversation, and is proposed as a stringency for which to strive.
Modern Halakhic Codes
Rabbi Yosef Karo in Shulhan Arukh 629:7 claims, based on a responsum of Rashba (n.215 of those originally attributed to Ramban) that it is “doubtful” whether one can use a ladder (which is arguably susceptible to impurity) to secure and support the sekhakh. This indicates his willingness to adopt the approach of Raavad, Ramban, and Ran against the approach of Rosh that he seemingly endorses later in 630:13.
Rabbi Avraham Gombiner in Magen Avraham 629:9, citing Bayit Hadash, notes this apparent inconsistency between the rulings recorded in Shulhan Arukh in 629:7 and 630:13, resolving it by explaining that Rabbi Yosef Karo adopts the more stringent approach as a stringency to be maintained ab initio when building the sukkah, but that post facto he adopts the more lenient approach, as above.
The reconciliation suggested by Magen Avraham is dismissed by Rabbi Eliyahu of Vilna (Beur ha-Gra 629:7) who strongly endorses the approach of Rosh that there is no problem of using a material susceptible to impurity to support the sekhakh.
Rabbi David Segal in Taz 629:10 understands the problem with the ladder as having nothing to do with it being a material which is susceptible to impurity supporting the sekhakh; rather the ladder is disqualified because it is 4tefahim wide, and thus understands the Shulhan Arukh as universally adopting the ruling of Rosh against Raavad, Ramban, and Ran.
The rulings of Rabbi Israel Meir Kagan in Mishnah Berurah and Rabbi Yehiel Mikhel Epstein in Arukh ha-Shulhan reflect these authors’ general approaches to dealing with these sorts of unresolved debates among medieval and early-modern commentators. Mishnah Berurah (630:59) first notes the accepted opinion of Rosh and then the stringency of Ramban:
דאף דמעמיד ע”ג מטה שהיא מקבלת טומאה לא איכפת לן בזה דקבלת טומאה על הסכך נאמר ולא על הדפנות. ומ”מ לכתחלה נכון להזהר בזה כי יש מן הפוסקים שמחמירין בזה, מ”א בסי’ תרכ”ט ס”ח.
Even though he supports [the sekhakh] on top of a bed which can become impure, we don’t care, because [the criterion that it not be susceptible to impurity] was stated regarding the sekhakh and not the walls; nonetheless, ab initio it is proper to be careful regarding this because some of the poskim are strict, seeMagen Avraham 629:8.
Mishnah Berurah adopts the more stringent approach either because he usually relies heavily on Magen Avraham (in this case traced back through Bayit Hadash to Ramban and Ran) or because he has a penchant suggesting legal interpretations that fulfill as many medieval approaches as possible. However, in his Shaar ha-Tziyyun n.60, he notes that although Alfasi, Rosh, and Rabbi Israel Isserlein (author of Terumat ha-Deshen) rejected the concern about the supporting material being susceptible to impurity, he nonetheless was concerned that Ran and Ritva’s interpretation of Alfasi was correct.
The Mishnah Berurah offers that after he explored the issue further, he discovered that many (perhaps even the majority of medieval commentators) reject this concern including Rabbi Yitzhak ibn Ghiyyat (Hil. Sukkah §241), Rambam, Rabbi Zerahiah ha-Levi, Rid (b. Sukkah 21b), and Rabbi Zedekiah ben Abraham (Shibolei ha-Leket§344 quoting Rid; however he also quotes Sefer Ha-Ittur who rules like Rabbi Yehudah). He concludes his footnote with a hedging recommendation echoing Magen Avraham to be stringent even if the law truly accords with the more lenient approach that would permit supporting the sekhakh with a material susceptible to impurity:
ובודאי יש לסמוך על דעת המקלין בזה, אכן לכתחילה נכון להזהר בזה לצאת ידי כל הדעות.
Certainly one can rely on the opinion of the lenient authorities in this matter; however, it is proper ab initio to be careful in this matter to fulfill the requirements of all authorities.
Arukh ha-Shulhan adopts a similarly characteristic approach to this question, cutting through the back-and-forth to a clear bottom-line recommendation based on the Yerushalmi, Rosh, and Beit Yosef. He discusses the position of Ran, as adopted by Rabbi Yoel Sirkis in his Bayit Hadash, and rejects it saying (Orah Hayyim 629:19):
למה לנו להחמיר ומה גם שכמה קושיות יש על שיטה זו … וכיון שכן הוא גם הכרעת רבותינו בעלי הש”ע והאחרונים אין להחמיר בזה.
Why should we be stringent, and further there are several challenging questions against this approach … and since this is the decision of our teachers the authors of the Shulhan Arukh and the later authorities one should not be stringent in this matter.
Although he sides more strongly with the permissive approach, using the powerful formulation “why should we be stringent,” he also engages with a bit of hedging (like Magen Avraham and Mishnah Berurah v.s.) in 630:35-36:
ויש מי שחושש לבלי להעמיד בדבר המקבל טומאה ולכן נמנעים מלקבוע מסמורות בסכך הסוכה ונכון הוא ומ”מ בדיעבד אין זה פסול מפני דרוב רבותינו לא חשו לטעם מעמיד בדבר המקבל טומאה וכן הוא בירושלמי.
And there are those who are concerned not to support [the sekhakh] with a material that can become impure, and therefore they avoid nailing down the sekhakh of the sukkah [with metal nails], and it is commendable; nonetheless, post facto this does not disqualify [the sukkah] because the majority of our rabbis were not concerned with the opinion that disqualifies [a sukkah] because [the sekhakh] is supported with a material that can become impure, and it is thus in the Yerushalmi.
Although he mentions that many (including Bayit Hadash, Magen Avraham, and Mishnah Berurah) see the ab initio stringency as a necessity, and commends their stringency, he concludes that the majority opinion and that which was codified in Shulhan Arukh is to be lenient, and that this is sufficient.
In conclusion, this sugya presents a range of practical conclusions stemming from a debate that illustrates many of the key details of talmud study: juggling different rules of adjudication—do we follow the majority or the opinion most discussed?—balancing the weight of Bavli and Yerushalmi, balancing the interpretations of different commentators, weighing how each of them is quoted and used by later authorities throughout the process of codification and super-commentary, and understanding the interplay between ab initio and post facto considerations.
Core pillars of halakhic jurisprudence—Rambam and Rosh—agree that there is no problem of using a material susceptible to impurity as a support for the sekhakh. This is also a plausible read of Alfasi and the Shulhan Arukh, leading me to agree with Arukh ha-Shulhan and the Vilna Gaon that regarding the practical Halakhah, one need not be overly concerned about this stringency.
Knowing that Raavad’s comments may have been written largely as a reaction to Rabbi Zerahiah ha-Levi’s comments, rather than to assert his own position and reading of the sugya and of Alfasi’s ruling, I am less inclined to adopt the interpretation of Raavad and Ramban. That said, the suggestion to be stringent as much as possible ab initio could very well be what the Mishnah and Alfasi really meant, and that position is certainly understandable.
In the final analysis, I am not compelled to be so overly concerned with this question to extend this already arguable stringency beyond its explicit scope—materials susceptible to impurity—to any material disqualified for use as sekhakh, e.g. plastic zip-ties. It is a difficult claim to make from within the text, and it is an unnecessary stringency that makes sukkah construction more difficult and dangerous for hard-working Jews during an already busy time of year.