Sukah Chart #8

Chart for Sukah Daf 19a

INVALID SECHACH AND OPEN SPACE:

Do they join with valid Sechach to make the minimum Shi'ur of a Sukah
and is it permitted to sleep beneath them?

(A)
INVALID SECHACH (1)
(B)
OPEN SPACE
LESS THAN 3 TEFACHIM
1 JOINS TO MAKE THE MINI-
MUM SHI'UR OF A SUKAH
Yes Yes (2) (3)
2 MAY SLEEP BENEATH IT Yes (4) No (5)
FROM 3 TO 4 TEFACHIM
3 JOINS TO MAKE THE MINI-
MUM SHI'UR OF A SUKAH
No (6) No (7)
4 MAY SLEEP BENEATH IT Yes(8) No
FROM 4 TEFACHIM AND ABOVE
5 JOINS TO MAKE THE MINI-
MUM SHI'UR OF A SUKAH
No No
6 MAY SLEEP BENEATH IT No No
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FOOTNOTES:

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(1) If a strip of invalid Sechach runs across the middle of the Sechach of the Sukah, it divides the Sukah in two. If one of the sides lacks 7x7 Tefachim or three walls, it is not a valid Sukah. If the invalid Sechach is toward the sides of the Sukah, then the Sukah is valid even if the invalid Sechach is up to 4 Amos wide (because of "Dofen Akumah"), but it does not join to make the Shi'ur of a Sukah, and nor is it permitted to sleep beneath it. (Some Amora'im maintain that the Shi'ur of 4 Amos applies even if the invalid Sechach is in middle of the Sukah -- Daf 17a,b.)

(2) This is because of "Lavud."

(3) There is an opinion in the Gemara (18a) that "Lavud" does not work in the middle. According to that opinion, open space less than 3 Tefachim does not join to make the Shi'ur of a Sukah, nor may one sleep under it, unless it was at the sides of the Sukah's roof. If it divides the Sukah such that on either side (or on both sides) there is not a large enough Shi'ur, the Sukah is Pasul. (This applies only when a strip of open space extends through the middle of the Sukah, from one side to the other.) The Halachah does not follow this opinion.

(4) This is evident from the case of using metal poles as beams to support the Sechach (15a), where we see that if there are spaces between them, the Sukah is valid, even though it is not possible to ensure that one sleeps only underneath the valid Sechach (TOSFOS DH Lo Yehei). Also, according to Tosfos, in a small Sukah one may not sleep beneath the invalid Sechach. Tosfos is in question about this point, though, and the Halachah does not follow that opinion.

(5) This is the way RASHI rules. (According to TOSFOS (DH Lo Yehei), though, it is also permitted to sleep under the open space. The Halachah does not follow this view.) According to the RAN, it is only prohibited to sleep underneath the open space if one's head and most of his body are underneath it. The TAZ writes that the reason open space in the Sechach is more stringent than invalid Sechach is because it is more noticeable (see Mishnah Berurah 632:10).

(6) This is clear from the Gemara earlier (17b). (However, RABEINU CHANANEL there argues and holds that invalid Sechach does join to complete the Shi'ur, unless it is more than 3.5 Tefachim, in which case there is more invalid than valid Sechach. See Insights there.)

(7) This is because it is no longer in the category of "Lavud." (8) This is according to RASHI (18a, DH sh'Ein Bah). However, the RA'AVAD (on the Rif) argues and prohibits sleeping beneath invalid Sechach when it is 3 Tefachim.