Shulchan Aruch: Chapter 628 - Laws Relating to a Sukkah [Constructed] Under another Sukkah

SECTION 628 Laws Relating to a Sukkah [Constructed] Under another Sukkah. (1–9)

1 [The following laws apply when] one sukkah [is constructed] under another sukkah,1 i.e., the s’chach of the lower sukkah is the floor of the upper sukkah. [See fig. 9, p. 270.] If there are at least ten handbreadths — the minimum acceptable height for a sukkah, as will be explained in sec. 6332 — between the lower s’chach and the upper s’chach, and [the floor of] the upper [sukkah is strong enough to support a person who] uses it [together with his] pillows and mattresses without falling into the lower sukkah, the upper sukkah is valid and the lower sukkah is invalid. [This concept is derived¹ from] the verse,3 “And you shall dwell in sukkos (בסוכת).” [This word is written] without a vav [in the third syllable],4 implying [that one must dwell under] one sukkah and not under two levels of s’chach.

If, however, it is impossible for [the floor of] the upper [sukkah to support a person together with his] pillows and mattresses even with difficulty, the upper sukkah is not fit to be dwelt in even temporarily. Since it cannot [support a person together with his] pillows and mattresses even with difficulty, it is not called a sukkah at all.5 Hence, the lower sukkah is not considered a sukkah beneath a sukkah and thus is not disqualified by it.

Similarly, if the upper sukkah is less than ten handbreadths high or the sunlit area [of its floor] exceeds its shaded area,6 it is not called a sukkah at all [and hence does not] disqualify the lower sukkah.

2 Therefore, [in the latter situations,] if the shaded part of the lower [sukkah] exceeds its sunlit area without including the shadow cast by the upper s’chach, [the lower sukkah] is valid without question, even if the s’chach of the upper sukkah is more than 20 cubits7higher than the floor of the lower sukkah.

[Theoretically, this situation could present a problem,] because the s’chach of the upper sukkah is invalid for the lower sukkah, being more than 20 cubits [above ground level].⁷ Here, then, is a situation in which material that is invalid as s’chach is casting a shadow over the lower sukkah, and, as explained in sec. 626[:2-3], material that is invalid as s’chach disqualifies valid s’chach that is placed under it.8 Nevertheless, in this instance, the lower sukkah is valid, even if the shadow cast by the upper s’chach exceeds the sunlit area [on the ground]. For the principle that invalid material disqualifies the valid s’chach below it applies only when the invalid material is inherently unsatisfactory; e.g., it is still connected to the ground or it is susceptible to contracting ritual impurity. When, however, the s’chach is inherently valid but is rendered unacceptable by an external factor — for example, by being situated more than 20 cubits above [ground level] — it does not disqualify the valid s’chach that is below it, for it is inherently suitable for use as s’chach for the lower sukkah.

3 [A different rule applies,] however, when the shade [on the floor] of the lower sukkah does not exceed its sunlit area¹ unless the s’chach of the upper sukkah is also taken into account. [In such a situation,] if the s’chach of the upper sukkah is more than 20 cubits from the floor of the lower sukkah, the lower sukkah is invalid, for invalid material9 cannot be counted together with valid s’chach to make up the required measure.

4 If a sukkah constructed upon a wagon or upon a boat10 cannot withstand ordinary land winds,11 it is invalid.12 A person who dwells in it — even when there is no wind at all — does not fulfill his obligation, because it is not deemed a dwelling at all.13 However, if [the sukkah] could withstand the winds common on land, then even if it could not withstand the winds common at sea, one fulfills his obligation, even if he dwells in it while the ship is at sea. [The rationale is that] a sukkah does not have to be a permanent dwelling (which is fit to live in for an extended period), but a temporary dwelling.14

5 [If a person] constructs his sukkah on a camel [see fig. 10] or on top of a tree, i.e., the treetop serves as the base of the sukkah and he builds walls and places s’chach over them [see fig. 11], it is valid.¹⁰ One may not, however, climb up to it on Shabbos or on a festival,15 for [at such times] it is forbidden to make use of any living creature or of any plant connected to the ground,16 as stated in sec. 336.17 We do not override even a shvus18 — which was ordained by the Sages — in order to enable the observance of the mitzvah of sukkah, for the reasons explained in sec. 586[:22].19

6 Even if the base of the sukkah is on the ground, but the canes of the s’chach are resting on a tree, it is forbidden to enter it on Shabbos or on a festival. This [safeguard] was ordained lest one use the s’chach by placing something on it or hanging something from it. Thus one would be making use of the appendages of a tree, for this is how the s’chach that is leaning on the tree is categorized, and it is forbidden to make use of such an entity on Shabbos or on a festival,20 as stated in sec. 336[:20].

7 When did the above apply? In earlier eras, when people would frequently use the s’chach, placing their articles on it and hanging them from it. In the present era, by contrast, when people are not accustomed to doing so, we do not have to take this possibility into account. Hence, permission may be granted to enter [such a sukkah] on Shabbos or on a festival. Nevertheless, as an initial preference, a tree should not be used as support for the s’chach, because [for this purpose] one should preferably use only objects that are fit to serve as s’chach, as will be explained in sec. 629[:11]. Note the explanation given there.21

8 If the ends of the canes of s’chach are resting on top of a camel, [the sukkah] is invalid, even after the fact, because it has no permanence. Ultimately, the camel will move from [that place] and the s’chach will fall.22 A sukkah constructed on top of a camel was permitted only when the s’chach was placed on walls that were built on the camel and thus the sukkah is carried with the camel.

9 [The following rule applies if] a person built part of the base for his sukkah and part of its walls on top of a tree and part of its base and walls on something else, and then placed s’chach on the walls.¹⁰ If [the sukkah] is constructed in such a manner that if the tree was removed, it would still stand on the other support without falling,23 one may enter it on Shabbos and on the festivals using a ladder that is not [supported by] the tree. If not [see fig. 12], one may not climb up to it on Shabbos and on the festivals. Since [in the latter instance] it is supported by the tree, a person entering it is making use of the appendages of a tree, as explained above.24

Fig. 12: See sec. 628:9.

As evident from this diagram, the leaves of a tree on which a sukkah was built should not cover the s’chach.