Ma’amid – The Supports of the Sechach
The Mishnah (Sukkah 21b) records a dispute between the Chachamim and R’ Yehudah as to whether sechach supported by the sideboards of a bed is valid. According to one explanation of the Gemara, R’ Yehudah invalidates it is because the sideboard of a bed is susceptible to tumah, and just as any item that is susceptible to tumah may not be used as sechach, it may also not be used to support the sechach.42 This is referred to as ma’amid — a support [of the sechach].
However, it is far from clear that this opinion is accepted as the halachah. Some Rishonim maintain that the halachah follows the opinion of the Chachamim, who allow for sechach to be supported by the sideboards of a bed. Yet others do rule like R’ Yehudah, but follow the Gemara’s alternative explanation of why a sideboard may not be used, according to which there is no rule that sechach may not be supported with an invalid item. Therefore, Mishnah Berurah43 rules that one should ideally refrain from supporting sechach with invalid material in deference to the opinion that this invalidates the sukkah, yet he states that when this is not feasible, sechach may indeed be supported by such material.
Question: Does this mean that a beam supporting the sechach may not be nailed into the wall, since the nail (which is invalid for sechach) will then be supporting the sechach — albeit indirectly?
Discussion: This scenario — where sechach is supported by something valid, but the support is itself supported by an invalid item — is referred to as ma’amid d’ma’amid (a support of a support). The vast majority of Poskim44 allow using an invalid ma’amid d’ma’amid. They maintain that the restriction of ma’amid applies only to the direct support of the sechach.
However, this involves some particulars. Several Poskim45 warn that simply placing a beam of wood on top of a wall made of an invalid material is insufficient. This is because the beam is not serving a significant role in supporting the sechach — it is simply interposing between the wall and the sechach and is not providing any practical benefit. Thus, we still consider the invalid wall to be the primary support of the sechach. Only if the support is indeed supporting the sechach in a practically significant way do we view its support as a ma’amid d’ma’amid and consider it acceptable. For example, one can place wooden slats perpendicular to the walls and then rest the sechach across the slats. In this case, the sechach would fall if not for the slats. Hence, we may view the slats as the supports and the walls as ma’amid d’ma’amid.
Note: Chazon Ish46 disagrees altogether with the distinction between ma’amid and ma’amid d’ma’amid. In his opinion, anything that supports the sechach even indirectly, at any level, must be valid for sechach [that is, according to the opinion that requires the support to be valid for sechach].47 This is to the exclusion of the floor. The floor may be made of any material, even though it, too, is integral in supporting the sechach.
To address some common cases:
Sechach may be laid directly on wooden walls.48
One should avoid laying the sechach directly on walls made of fiberglass, on a metal frame, or the like.
Sechach may be laid directly on walls made of stone.49 This is an exception to the rule; although stone is invalid as sechach, Ran (folio 10a) explains that the restriction of supporting the sechach with something invalid is limited to materials which might ostensibly be used to roof a temporary dwelling. Then, there is concern that if one uses them to support the sechach, one might come to use them as the sechach itself. However, since stone is not commonly used for this, it is not included in the restriction.50 This is true even for a stone wall that has metal rods inside it, since they are not truly needed and are added only for extra support.51
Sechach may be laid on a wooden pergola or on a wooden frame.
One may attach a wooden beam to the wall and place the sechach on the beam. This is acceptable even if the beam is nailed to the wall, as above. However, this must be done in a way that if the beam were removed, the sechach would fall, as above.
One can place slats across the walls perpendicularly and lay the sechach on the slats. Here as well, this must be done in a way that if the slats were removed, the sechach would fall.
Question: May the sechach be tied down, or weighted down, with something that is invalid for sechach?
Discussion: It is clear from Rema52 that this, too, is considered a form of ‘supporting the sechach,’ so this should also ideally be avoided, if possible.53 Remember, however, that refraining from supporting or tying down the sechach with something invalid is a preference, while ensuring that the sechach is not vulnerable to the wind is essential to the sukkah’s validity. Therefore, if one does not have something valid available to tie down the sechach, one should not hesitate to use an invalid item.
In conclusion: It is important to remember that while it is preferred that the sechach be supported with something valid, strict halachah follows the view that anything may be used to support the sechach. Therefore, if no practical solution is available, one may support the sechach with whatever works.
42. Note: Although the Gemara speaks specifically of items that are susceptible to tumah, that is merely an example of an item that is invalid for sechach, but in fact, the restriction includes anything invalid for any reason (e.g., metal, which is invalid because it does not grow from the ground). This is evident from the many Rishonim there, who challenge this rule from Gemaros which discuss sechach that is supported by materials which are invalid for other reasons (see, however, Me’iri 21b, 22b; and see Otzar Mefarshei HaTalmud, Sukkah 21b, footnote 28.
43. 630:59 (see, also, Sha’ar Hatziyun 60); 629:22.
44. Magen Avraham 629:9; Beiur HaGra 629:7; Mishnah Berurah 629:26; He’aros (R’ Yosef Shalom Elyashiv) 21b; Minchas Shlomo, II:55.
45. Mikra’ei Kodesh 21; Mishulchan Melachim V, p. 99, citing R’ Yosef Shalom Elyashiv.
46. Ibid. It is of note that Terumas Hadeshen (91) also indicates that there is no difference between ma’amid and ma’amid d’ma’amid. However, Terumas Hadeshen rules that one need not be concerned with either.
47. Thus, according to Chazon Ish, a number of the solutions presented below are not effective. This includes any case where the sechach rests on something that is itself supported with metal nails. [Those who adhere to Chazon Ish’s stringency will often use specialized wooden nails for the various parts of the sukkah that ultimately support the sechach.]
48. The walls are usually too wide to be used as sechach (see Shulchan Aruch 629:18). However, since they are only invalid rabbinically, Pri Megadim (Eishel Avraham 629:11) suggests that perhaps items that are only rabbinically invalid may be used as supports. Pri Megadim concludes that a God-fearing individual should refrain even from this, but Bikkurei Ya’akov (629:14) argues that this is an extreme stringency. Beiur Halachah as well (630:1, ד”ה כל) states that, rabbinically, invalid items may be used to support the sechach.
49. Mishnah Berurah 629:22.
50. Mishnah Berurah (ibid). See Hilchos Chag Bechag (volume I, p. 192) for further elucidation of this principle.
51. Chazon Ish 143:2.
52. 629:7, Mishnah Berurah 629:24.
53. Shevet HaLevi (IX, chapter 137) rules that one may weigh sechach down with stones, just as one may support sechach on a stone wall, as above.
Note, also, that if the sechach is essentially sturdy enough to withstand strong winds and one is merely tying it down for extra security, one may use an invalid material.