Siman 632

We maintain that invalid sakhak invalidates the entire sukkah in the middle at four tefachim, and from the side at four amot. And air invalidates the entire sukkah, whether in the middle or from the side, at three tefachim (17a). And the explanation of the matters: when there is a sukkah of three walls, and the fourth side is breached, and the invalid sakhak or the air begins from the start of the middle wall, and goes across the entire sukkah until the breached wall, and divides the sukkah into two parts, and each part remains with only two walls. Therefore, when the separation is less than three tefachim—it is like lavud, and is nothing. But three tefachim of air—it divides into two, and it is completely invalidated. And invalid sakhak does not divide except at four tefachim, as this is a significant place. But less than four—it is not significant enough to divide it. And that which air divides at three—is because the division is clearly recognizable. And necessarily, once it has left the status of lavud—it divides. But invalid sakhak, where the division is not recognizable—it does not divide except in a significant place: four tefachim.

Airspace that disqualifies at three tefachim — disqualifies whether it is in the middle of the sukkah or at the side. However, invalid sechach — does not disqualify at four tefachim except in the middle. But at the side — it does not disqualify until four amot, because we say: dofen akumah. That is to say: we see that this continuation of the invalid sechach placed on the roof, we consider it as if it is from the wall, except that the wall was bent over the roof. And this matter is not from logic, but is a halachah le-Moshe mi-Sinai, that we say regarding invalid sechach at the side dofen akumah up to a span of four amot. And regarding airspace it is impossible to say so, for there is nothing to establish as a wall.

That which we have said in the explanation of dofen akuma, that we consider the sechach as if it is part of the wall, and it was curved and bent – so wrote Rashi (17a), and so wrote the Rambam in the fifth chapter at the end of law 14, and this is his wording: We view it as if the wall was curved, and this invalid sechach is considered part of the body of the wall – and it is kosher. And this matter is a Halacha LeMoshe MiSinai. Thus far his words. But if so, it must be understood: since we consider it part of the wall, if so, the kosher sechach is very far from the wall? However, it appears in my humble opinion that the matter is thus: for so the Halacha was stated – that we consider the invalid sechach as if it is part of the wall and was curved, and afterwards we consider it as if the wall continues to curve and reaches the kosher sechach. And a proof for this matter is from that of the istaba, which will be explained in the next siman, when the sukkah is higher than twenty amot, and one built an istaba in it to diminish the height. And we say in the Gemara (4a) that if there is from the edge of the istaba to the wall less than four amot – it is kosher due to the reason of dofen akuma. And there, perforce, it is as if the wall was curved and came to the istaba, and as the Rambam wrote in the fourth chapter, law 14, and this is his wording: If one built an istaba in its middle… less than four amot – it is kosher, and it is as if the partition touches the istaba… Thus far his words; behold, it is explicitly like our words. (And that which Rashi there rejected this explanation – that is to say, not this alone, but both are necessary. And also regarding the istaba one can say so, see there. And examine closely and you will find it simple.)

Some say that we do not say dofen akuma except with partitions that reach the s'khakh. But if the partitions do not reach the s'khakh – we do not say dofen akuma (Ran and Kesef Mishneh there). And the reason appears to be that wherever air intervenes, even in height – there is no place for the partition to join it, and how can we say that the invalid s'khakh is part of the partition and has become curved? For it does not reach the partition that is at the side, because of the intervening air. But the Tur wrote that we say dofen akuma even if the partition is only ten tefachim, and the roof is much higher than it, for we view the partition as if it rises upward, and then we say dofen akuma. Thus far his words. That is to say: that we view this itself as if the partition rises upward. And if it is difficult: if so, let us say dofen akuma even with air? For it is not so, as specifically regarding the air of the partitions that is above the minimum height for the fitness of a sukkah, which is not necessary – one can say this, but not regarding air on the roof, which is the primary place of the fitness of the sukkah. And regarding the law, one should be stringent. (And so wrote the Bach, and the Magen Avraham subsection 1. And the Taz subsection 1 lengthened to question those who are stringent. And according to what I have written, it works out well. Examine it and you will find it simple.)

And know: that regarding pasul sechach of less than four tefachim – it is permitted to sleep under it, for it is nullified relative to the entire sukkah. However, from the side, where it invalidates at four amot, and with less it is kosher – one should not sleep under it when its width is four tefachim, for it is a significant place. And regarding an air space even of less than three, which does not invalidate the sukkah – nevertheless, one should not sleep under it, even though less than three also joins for the koshering of the sukkah, as will be explained. Nevertheless, one is not to sleep under it when it runs across the entire sukkah, for it is very noticeable; or even if it does not run across the entire sukkah, but rather it has a length in which a person can sleep against it his head and the majority of his body. But otherwise – it is permitted, for you have no sukkah that does not have small holes. Rather, when there is an air space of a proper length – one should not sleep under it, nor eat nor sit under it. And it is not similar to pasul sechach, because it is very noticeable.

And that which we distinguished between airspace and pasul sechach, and between the middle and from the side – this is all in a large sukkah. But in a small sukkah, which has only the minimum size of a sukkah of seven tefachim – there is no distinction between airspace and pasul sechach, nor between the middle and from the side. Rather, in all cases, less than three – it is kosher, and it joins to the minimum requirement of the sukkah, and one may sleep under it, for it is considered as lavud. And three tefachim is pasul. And the reason is simple: for since it is small, it is impossible to have pasul sechach in it up to the measure of four tefachim. For if so, the majority of it would be pasul, and one must necessarily go according to the measure of lavud. And anything that has departed from the law of lavud – it is pasul in every matter and in every place.

Dofen akuma, which was stated as a halacha regarding four amot—this applies whether to one wall or to all the walls. Therefore, a house whose roof was breached in the middle, and one placed s'chach in the place of the breach, and there remained from the ceiling around it between the kosher s'chach and the walls less than four amot—it is kosher. However, one may not sleep under it as long as it has four tefachim. And if in one place there are four, and in another place less—it is permitted to sleep in the place of the less.

This which has been explained, that פסול סכך disqualifies in the middle with four tefachim, and air disqualifies with three, is as I have written: when the sukkah has only three walls. And it begins at the middle wall and runs across the entire sukkah until the breached side. For now the disqualification or the air separates between kosher סכך and kosher סכך, and there remains on each side only two walls. But if it begins from the wall on the side and runs until the second wall opposite it, if there remains of the kosher part toward the middle wall the minimum for a kosher sukkah, which is seven tefachim—it is kosher, for it has three walls. And the side beyond the opening, which is toward the breached side, if the separation is with three tefachim of air—it is disqualified in any case, as I have written. But if פסול סכך separates with four tefachim, and by the opening there still remains the minimum for a kosher sukkah, if there is from the kosher side until the middle wall enough to say דופן עקומה, which is less than four amot—the entire sukkah is kosher: the inner side has three walls, and the outer side is rendered kosher by means of דופן עקומה, for we view the middle wall as if it stands next to the outer side. And one should not say: since we take the wall from there, how can the inner side be kosher? For in truth we do not take it from there, we only view it as if it stands there, and automatically the whole thing is kosher (Tur). And it is simple that if the third wall is only seven tefachim, and there are four tefachim of פסול סכך after the seven tefachim toward the breached wall—only the inner side is kosher. But the outer side—it has only two walls (ibid.), the long wall and the middle one, and it is disqualified.

All of this is when the air or the invalid material extends across the entire sukkah. However, if in the middle of the sukkah there is air of three by three, or invalid s'chach of four by four, and on the sides the valid s'chach is connected to one another, if there is from the air or from the invalid material the valid measure of a sukkah until the middle wall – everything is valid. For that which is on the sides – it is obvious that it is valid, for it is connected to the valid measure of a sukkah. And likewise, that which extends from the sides toward the side of the entrance – it is connected. And even the valid measure that is after the invalid material, or after the air toward the side of the entrance, whose connection is only by way of the sides – nevertheless, ultimately it is connected to the valid measure of a sukkah. And it is no worse than a branch extending from the sukkah, which is judged as the sukkah, as I wrote in the previous siman. And only under the air and under the invalid material alone – it is invalid to sleep there, as I wrote. And in truth, even if there is not from the air or from the invalid material the valid measure of a sukkah until the middle wall – we also have no concern with it, for the entire sukkah joins together for the valid measure of a sukkah, since they are connected from the sides (ibid.).

If there is invalid sechach of less than four tefachim, and next to it is airspace of less than three tefachim—they do not combine with one another to invalidate the sukkah. Therefore, if there is airspace of three tefachim—one may diminish it with invalid sechach, and it is valid. And this is specifically in a large sukkah. However, in a small sukkah that has only seven by seven—they combine with one another to invalidate. And this is not because of combination, but because of a deficiency in the required measure. And if there is invalid sechach of two tefachim, and afterwards airspace of less than three tefachim, and afterwards more invalid sechach of two tefachim—the Rosh, of blessed memory, is in doubt whether the two invalid sections combine to invalidate the sukkah. Do we say: since airspace separates between them—they do not combine? Or perhaps: since there are not seven in the airspace—they combine. And this is not due to the principle of lavud, for we do not say lavud to be stringent. For if they said lavud to be stringent—it would be sufficient to have a tefach of invalid sechach from here, and a tefach from here, and between them two tefachim of airspace, and through lavud it would become four tefachim of invalid sechach. Rather, certainly we do not say lavud to be stringent. And even the one who holds that we do say lavud to be stringent—we only say it so that they are considered as if both are adjacent to one another, but not that the airspace should combine (see Magen Avraham subsection 5, and above siman 502 subsection 9). Rather, here the doubt is that since it is not a significant area—it is not significant enough to separate, and it is as if they are joined, and it is invalid sechach of four tefachim. And we follow the stringent view, for this is a doubt regarding a Torah law.

It is stated in the Gemara (14b) that regarding that which we say that pasul schach invalidates at four tefachim—even if the entire four tefachim are not within the sukkah, such as if one placed pasul schach on the sukkah near a breached wall. For it is impossible to say there the law of dofen akumah, since there is no wall there, and he brought three tefachim into the sukkah and one tefach outside the sukkah—it is like a beam extending from the sukkah and is judged as the sukkah, and the three tefachim are considered as pasul schach. And it is forbidden to sleep under it, because the tefach that is outside is considered as if it is inside. And if it is a small sukkah—the entire sukkah is invalidated, for it is like a small sukkah that has four of pasul schach, which is entirely invalidated, as has been explained. And according to this, even if it is not on the breached side, but rather on the side of the wall, where one could say dofen akumah—nevertheless, in a small sukkah the required measure is lacking (Maharsha ibid.).

And according to this, one must be careful with our constructed sukkot, where until the place of the roof opening there is a bit of building, which is like invalid sechach. And it is true that it is less than four tefachim, but in most of them, some of it also protrudes outside the wall to the exterior of the sukkah, and together it would be four tefachim. And if so, it is forbidden to sleep under it. And there is one who says that since there is a wall between them—they do not join together. Therefore, if there are not four tefachim of invalid sechach within the sukkah—it is permitted to sleep under it (Magen Avraham end of subsection 1). And one should be stringent like the first opinion. (Also the Chemed Moshe disagrees with the Magen Avraham. And the Pri Megadim as well is like one who is uncertain in this, and inclines to be stringent, see there.)

And know that this which we say, dofen akuma up to four amot—this is in the horizontal span. But in a sloped roof, even if there are four amot or more in its slope, if there are not four amot in the horizontal span—we say dofen akuma (Magen Avraham subsection 2). And regarding that which we say that in a small sukkah of seven tefachim—any three tefachim invalidates the sukkah: it is not specifically seven tefachim, but rather any that is less than ten tefachim—three tefachim invalidates, since there will not remain seven tefachim, the minimum measure of a sukkah (ibid. subsection 3). (And regarding what the Magen Avraham wrote in subsection 2, that if the roof is curved above, going in a slope, and it does not have four amot in the horizontal span, and only in its slope below there is a beam within less than three tefachim, that if it joins with it there would be four amot, and we do not say dofen akuma—nevertheless, since on the side of the height it is three tefachim distant, and if so one must say chabut and lavud. And we do not say so to be stringent, see there. And this is according to his view in siman 502, that we say lavud to be stringent, as I wrote in section 10. But according to those who say that we do not say lavud to be stringent, even without chabut we do not say lavud. And similarly wrote the Ran, of blessed memory, regarding the dispute of Rav Aha and Ravina 18a, that we do not say lavud and dofen akuma together, see there and in the Machatzit HaShekel subsection 2.)