Question: (Why is a Sukah taller than 20 Amos invalid? A Sukah is supposed to be a person's abode for seven days and) surely a house taller than 20 Amos is obligated to have a fence around the roof and is obligated in Mezuzah!

Answer: A house is roofed (so it is considered a house even if taller than 20 Amos) but a Sukah is not (as it only has Schach).

Rejection: But we find that Schach is called roofing, as the Mishnah teaches - If one distanced the Schach from the walls three Tefachim, the Sukah is invalid (as we apply the concept of Lavud to consider the area closed up - and Lavud is a concept that relates to houses)!

Answer: Rather, a house is closed on all four sides but a Sukah is not.

Question: A pavilion that is open on all four sides to a public domain - R. Ila quoting Rav and R. Yochanan both said that one may carrying underneath it. (It is treated like a house even though there are no walls.)

Question: If so, why is a Sukah different from a house (that above 20 Amos is invalid)?

Answer (R. Abahu quoting R. Yochanan): The Torah says (Vayikra 23, four2), "You shall dwell in Sukos" - until 20 Amos, a person sits in the shade of the Sukah (Schach); above 20 Amos he sits in the shade of the walls.

R. Yona: A Sukah taller than 20 Amos is invalid only if the Schach is more than 20 Amos above the walls, but if the Schach is within 20 Amos of the walls, even if it is more than 20 Amos from the ground, it is valid. (This disagrees with R. Abahu's version of R. Yochanan who said that the reason that over 20 Amos is invalid is because the shade is coming from the walls.)

Question (R. Yosa to R. Yona): According to you, that it depends on the walls, the Mishnah should teach - "A Sukah (Schach) that is put more than 20 Amos above the walls is invalid"?

R. Ba quoting Rav: A Sukah taller than 20 Amos is invalid only if the Sukah is large enough to hold only his head, most of his body and his table; but if it is larger, it is valid.

R. Yaakov bar Acha quoting R. Yoshiya: A Sukah taller than 20 Amos is invalid only if the walls do not reach the Schach, but if they do, it is valid.

Question: There is a Beraisa that disagrees with R. Ba who quoted Rav (d) -

R. Yehuda says - There was a story of the Sukah of Queen Heleni in Lod that was taller than 20 Amos and the Chachamim came and left and did object to it. (This proves that a Sukah taller than 20 Amos is valid!)

The Rabbanan replied - She was a woman and a woman is not commanded in Mitzvos.

R. Yehuda replied - That does not prove anything as she had seven learned sons!

Conclusion of question: Could you suggest that Queen Heleni's Sukah only held a person's head, most of his body and his table?! (She certainly had her children or servants with her - so if it was a large Sukah, according to R. Ba, even the Rabbanan should agree that it was valid!)

Question (against R. Yoshiya): Furthermore, would a queen sit in a Sukah where the walls do not reach the Schach?

Answer (for R. Yoshiya): Wealthy people do sit in such a Sukah so that the cool air and ventilation will enter.