Invalid Schach — Above the Balcony

Hello, honorable Rabbi.

I am planning to build a sukkah on a balcony. Above the entire balcony there are Suntuf panels (invalid schach), and I moved them to the left side, stacked one on top of another. Now about two-thirds of the balcony is open to the sky, and on the left third the Suntuf panels remain. The width of the area beneath the Suntuf panels is less than four amot, but the invalid schach also continues beyond the area of the sukkah, and together it is more than four amot.

I saw in Mishnah Berurah siman 632, and likewise in Piskei Teshuvot there, section 5, that in such a case we do not apply dofen akumah if the invalid schach continues outside the sukkah, similar to the case of rods that he turned over. I also saw there that if there is a wall beneath the invalid schach, there are opinions that the wall must reach the schach, and that a wall of ten tefachim with the principle of gud achit is not sufficient.

On my balcony, the left wall is a railing ten tefachim high, and it does not reach the schach. Therefore, I am planning to make a new wall between the area open to the sky and the area beneath the Suntuf panels. I wanted to position the wall slightly under the Suntuf panels, in order to gain a few more centimeters for the sukkah area, and not exactly at the line where the invalid schach begins.

In such a case, am I obligated to make a full wall that reaches the schach? Is it possible to make a wall from several boards along its length in a manner of lavud? And if the wall extends less than 24 cm under the invalid schach, is it sufficient to make a wall only ten tefachim high?

Hello and blessings 

The discussion regarding invalid schach that extends outside the sukkah applies only in a case where one wants to divide the schach so that it will be less than four amot and be effective through the law of dofen akumah. However, when the invalid schach is truly situated outside the walls of the sukkah, there is no problem at all with the fact that it continues. 

If you extend the wall up to the schach itself, it will certainly be effective. In such a case, it is possible to distance the wall by up to three tefachim so that you will be able to sit beneath it.  

Lavud between the walls is effective. But there are opinions that the walls must be attached to the schach, and that one should not rely there on lavud for the connection. 

Shulchan Aruch, Orach Chaim, siman 632

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