Glass walls for the sukkah are kosher, but those who dwell therein still shouldn’t throw stones. TB Sukkah 7

Today’s daf TB Sukkah 7 teaches an important halakha. What makes a sukkah a sukkah is the sakhakh, the roof. We shall learn later that kosher sakhakh must have grown from the ground and now is detached. We layer the sakhakh on top of the sukkah to form the roof. The Mishnah teaches us “And a sukka whose sunlight, i.e., the sunlight that passes through the roofing, is greater than its shade, is unfit.” (Sefaria.org translation)

The Gemara defines where the shade is necessary. “The Sages taught in a baraita that in the statement: Whose sunlight is greater than its shade, the reference is to sunlight that passes through due to sparse roofing, and not to the sunlight entering due to gaps in the walls. It is possible for a sukka to have more sunlight than shade due to sunlight passing through the sides and not the roofing, in which case the sukka is fit. Rabbi Yoshiya says: If the sunlight exceeds the shade the sukka is unfit, even if the sunlight is due to gaps in the walls.

“Rav Yeimar bar Shelemya said in the name of Abaye: What is the rationale for the statement of Rabbi Yoshiya? It is as it is written: “And you shall screen [vesakkota] the Ark with the curtain” (Exodus 40:3). The curtain is a partition and not a covering over the Ark, and nevertheless, the Merciful One calls it roofing [sekhakha]. Apparently, we require the purpose of a partition to be similar to the purpose of roofing; just as the roofing must be mostly impermeable by sunlight, so must the partition.

And how do the Rabbis, who disagree with Rabbi Yoshiya, interpret the term: And you shall screen [vesakkota]? That term teaches that we should bend the top of the curtain a bit so that it appears as roofing over the Ark.” (Sefaria.org translation)

The halakha follows the sages. (Shulkan Arukh, Orekh Hayim, 630:1) Based on this ruling, a person may build a sukkah using translucent or transparent walls and not worry whether the entering sunlight from the walls would invalidate the sukkah. Alternately, if a person’s walls don’t go up to the roof for ventilation purposes and sunlight shines through this small gap of no more than 3 handbreadth, you still have a kosher sukkah.