Misconception: If stars are not visible through the schach (roof of the sukkah), the sukkah is invalid.

Fact: According to many opinions, ab initio, one should be able to see starlight through the schach. However, even if one is unable to see stars, the sukkah is kosher according to most authorities.

Background: A sukkah has two main components—the walls and the schach. Each of these has its own set of requirements regarding materials used, size and durability.

Because a sukkah must be a temporary dwelling,[1] there are certain guidelines governing its construction. For example, the rabbis banned the use of certain building materials for schach including boards that are four tefachim wide (about twelve inches), which were commonly used for roofs during the Talmudic period.[2]

To further distinguish a sukkah from a permanent edifice, the Talmud Yerushalmi says that the schach should not be so thick as to prevent one from seeing stars. The Shulchan Aruch (OC 631:3) does not follow this ruling and states that even if the schach is as thick as an ordinary roof, such that no stars are visible, it is kosher as long as it is made from appropriate materials. Despite the ruling of the Shulchan Aruch, the Mishnah Berurah (631:5) cites later authorities who require that some stars be visible through the schach. Nonetheless, the Mishnah Berurah (631:6) rules that a sukkah in which stars are not visible through the schach is kosher. The Mishnah Berurah also cites the Peri Megadim as saying that even according to those who require stars to be visible, if there is at least one spot in the schach where the stars can be seen, that suffices to make the entire sukkah acceptable. The Aruch HaShulchan (631:6) also recommends this method of constructing a sukkah but states that, post facto, the sukkah would be acceptable even if it were not constructed in such a manner.

A related issue concerns whether or not rain can penetrate the schach. The Tur (OC 631) and the Mishnah Berurah (631:6) quote Tosafot,[3] who, they claim, implies that if rain cannot penetrate the schach, it is a sign of permanence and hence, the schach is not kosher even post facto.[4] Tosafot maintains that the sukkah must be constructed in such a manner that the walls could be potentially temporary or “flimsy.” Once the walls have that potential, they may even be made of bricks and cement. However, it is not enough for the schach–which is the essence of the sukkah–to be potentially temporary; it must truly be of a temporary nature. Schach that is impenetrable to rain is, by definition, permanent, and according to Rabbeinu Tam, invalid. The Mishnah Berurah views such thick schach as invalid and maintains that even an area of such schach measuring four tefachim wide and running the length of the sukkah would invalidate the entire sukkah.

Rav Moshe Sternbuch (Moadim U’zmanim 1:96) disagrees with the above and asserts that the sukkah is invalid only if the entire roof has such schach. According to him, even a small section of schach that rain can penetrate would validate the sukkah. Emphasizing his point, he cites Rav Chaim Volozhin’s tradition of having thick schach throughout the sukkah, with the exception of a small section. This enabled Rav Chaim to fulfill the mitzvah of eating in a sukkah even when it was raining (Moadim U’zmanim 8:1:06).

The discussion of how much “thick schach” invalidates the sukkah is predicated on Rabbeinu Tam’s position that if rain cannot penetrate the schach, the sukkah is invalid. While this position is accepted by the Levush and the Bach (OC 635), it is not cited by the Shulchan Aruch[5] who rules quite clearly (OC 631:3) that even if the schach is as “thick as [the roof on] a house” it is kosher. The Tur (near the beginning of OC 631) cites Rabbeinu Tam’s position and then states (with seeming approval) that his father, the Rosh, did not cite Rabbeinu Tam’s position in his rulings.[6] The Beit Yosef (OC 631) cites the Mordechai (Sukkah, chap. 1) as pointing out that Rashi seems to disagree with Rabbeinu Tam as well. Furthermore, the mishnah on Sukkah 22a[7] seems to support the Rosh’s position that rain-tight schach is valid. Incidentally, it seems that[8] Rabbeinu Tam had a brother-in-law who did not agree with his ruling and constructed a rain-tight sukkah.

This debate seems to have pitted many Rishonim against each other.[9] However, most of the Acharonim felt that one should try to build a sukkah that is not watertight. Both the Mishnah Berurah and the Aruch HaShulchan rule that, post facto, one may use a sukkah that is impermeable to water and rely on the opinions that reject Rabbeinu Tam’s position.

The reason many people believe that stars must be visible through schach and that rain cannot penetrate schach at all may be due to the immense popularity of the Kitzur Shulchan Aruch (Rav Ganzfried) and the Chayei Adam (Rav Danziger). These halachic works, written about 150 years ago, were widely studied by Eastern European Jews. The Kitzur Shulchan Aruch (134:5) writes that, ab initio, one should be able to see stars through the schach and, post facto, the schach is invalid if rain cannot penetrate it.[10] Similarly, the Chayei Adam (147:18) rules that if no stars are visible the schach is valid, but preferably them schach should be sparse enough to see stars. He further rules that if heavy rain cannot penetrate the schach it is invalid because of the rabbinic decree against building a sukkah like a house (gezeirot bayit).

There are thus two halachot regarding the thickness of the schach; one is related to stars, the other to rain, and both contain philosophical nuggets as well. Seeing the stars while in the sukkah emphasizes the ephemeral nature of existence and highlights the idea that we are sitting under God’s watchful eye. Similarly, the sukkah provides inadequate protection from the elements so that one realizes that just as the Jews in the desert relied on God’s protection from the elements, we must rely on that protection today.

Philosophy aside, the requirement to see the stars was not accepted as binding by any authorities and is merely offered as a worthy suggestion. On the other hand, while the Talmud and many early authorities did not rule out schach that is rainproof, it was deemed unfit by no less than the great Rabbeinu Tam and was therefore strongly opposed by later codifiers.

Notes 1. This is in contradistinction to the opinion (offered by Rabbi Yehudah, Beit Shammai, Rebbi, etc.) in Sukkah 7b that a sukkah must be a dirat kevah, a permanent dwelling. The halachah does not agree with the opinion above but rather with that of Rabbi Akiva (in Sukkah 23a) and others who state that it must be a dirat aray, a temporary dwelling.

2. See Shulchan Aruch OC 629:18. Whether this decree includes thinner slats of wood that are bound together is subject to debate. See Rabbi Yeshai Koenigsberg, “The Canvas Succah,” Journal of Halacha and Contemporary Society 15 (Sukkot 5761): 27-45, in particular: 44-45.

3. Tosafot, Sukkah 2a, s.v. ki avid. This is based on a gemara in Ta’anit 2a that views rainfall on Sukkot as a bad omen since it prevents one from fulfilling the mitzvah of sukkah. Based on the gemara, Tosafot states that sukkot cannot be raintight. The Pnei Yehoshuah, commenting on this Tosafot, has a problem with that logic. He argues that this gemara is not a proof that sukkot may not be rain resistant; it is merely that most sukkot are in actuality not watertight.

4. The Taz (OC 629:21) writes that even though the verse (Deut. 16:13) expressly sanctions using straw as schach, it is common to use branches and the like. This is because unlike branches or bamboo, straw that is packed tightly prevents rain from entering the sukkah. The Taz (OC 635:2) then questions how a hollowed-out haystack may be a good sukkah since it is impermeable to rain. He concludes that even according to Tosafot, a rainproof sukkah is only invalid rabbinically because of the concern that it will be confused with an ordinary permanent house, which would not apply to a haystack. The Peri Megadim (Mishbetzet Zahav, 635:2) disagrees, claiming that Tosafot believed that such a sukkah was invalid even Biblically, and this seems to be how most understand the Tosafot.

5. See, however, Tur OC 629 (near the end) in the name of the Smak, who implies that the halacha of not using boards for schach is based on the reasoning of Rabbeinu Tam. Thus, according to the Smak, the Shulchan Aruch does follow the opinion of Rabbeinu Tam. See also Sha’arey Tziyun 633:6.

6. In actuality, the Rosh cites this Rabbeinu Tam in siman 12. However, the Beit Yosef explains that when the Tur claims that the Rosh omits this halachah, he means that he omits it in its proper place, that is, in the mishnah in Sukkah 22a.

7. The mishnah implies that, a priori, one should be able to see the stars, but states that if one cannot, the sukkah is still kosher. According to Beit Hillel in the gemara, even if the sun’s rays do not penetrate the schach, it is still kosher.

8. See Hagahot Maimoniot, Hilchot Sukkah 5:9.

9. On the lenient side were Rashi, the Rosh, the Mordechai and Rabbeinu Tam’s brother-in-law, among others.

10. Rav Ovadiah Yosef rules similarly [as recorded by his son in Yalkut Yosef-Moadim, (5748, p. 130)]. See the comprehensive discussion in Yabia Omer 4:49.

Reprinted from JEWISH ACTION Magazine, Fall 5764/2003 issue