May one eat under an area in the Sukkah that is not covered [is open to the sky]?

If the area is less than 3×3 Tefach it is permitted to eat under the area. If the uncovered area stretches from wall to wall, then if it is three Tefach wide, the Sukkah is considered split in half and is possibly invalid if it will lack three walls due to this. If the uncovered area is adjacent to the walls then if it is three Tefach wide, the adjacent wall is invalidated. This can possibly invalidate the entire Sukkah if the Kosher Sechach will not remain with 3 Kosher walls.

 

May one eat under an area in the Sukkah that contains invalid Sechach over it?

If the invalid Sechach passes from one end of the Sukkah to another: If the invalid Sechach is 4 Tefach [32 cm] wide, and passes from one end of the Sukkah to another, it is considered as if the Sukkah is split in half. Thus if the Sukkah has three walls it is possible for the entire Sukkah to be invalid. If the Sechach is less than 4 Tefach wide the entire Sukkah is Kosher and one may even eat under the non-Kosher Sechach. However some rule that if the non-Kosher is 3 Tefach wide one may not eat under it. Practically one is to initially be stringent and not eat under that area. If the Sechach is less than 3 Tefach wide one may eat under the non-Kosher Sechach according to all opinions.

If the invalid Sechach does not pass from one end to other: If the invalid Sechach is 4 x4 Tefach [32×32 cm] wide then one may not eat under that area. If the area is less than 4×4 it is valid to eat and sleep under it.

If the invalid Sechach is adjacent to the walls of the Sukkah: If the invalid Sechach is less than 4 Tefach wide one may even eat under it although practically one is to be stringent if it is 3 Tefach wide. If the invalid Sechach is more than 4 Tefach wide but less than 4 Amos the Sukkah remains Kosher as we apply the rule of Dofen Akuma. Nevertheless one may not eat under the non-Kosher Sechach. If it is more than 4 Amos wide the wall that is adjacent to the invalid Sechach is considered non-existent and can possibly invalidate the entire Sukkah if the Kosher Sechach will not remain with 3 Kosher walls. [Some Poskim[1] rule that in order to apply the rule of Dofen Akum the wall must reach the invalid Sechach. If the wall is distanced from the invalid Sechach then it is disputed if we apply the rule of Dofen Akuma.[2]]

---

[1] M”B 632/4

[2] M”B rules that if it is within 3 Tefach it is valid. Rabbi Akiva Eigar 12; See Piskeiy 632/3