(Mishnah): An old Sukah - Beis Shamai say that it is invalid and Beis Hillel say that it is valid.

What is considered old? If he built it more than thirty days before the festival; but if he built it as a Sukah for the festival, even if he built it at the beginning of the year it is valid.

(Gemara - Beraisa): (Even according to Beis Hillel who say that an old Sukah is valid, ideally) he must make an addition to the Sukah (to show that he built it for the festival).

Chevraya said that he must add a Tefach; R. Yosa said that he can add any minimal amount.

According to R. Yosa, he must add that amount to the entire length or breadth of the Sukah.

The same discussion applies to an old Matzah, that Beis Shamai say that it is invalid and Beis Hillel say that it is valid.

R. Yosa: All agree that an old Matzah is invalid - if he did not bake it for Pesach, he will certainly not be careful about preventing it from becoming Chametz.

A shepherd's Sukah (that he builds to protect him from the sun when working) and a potter's Sukah (where he makes his pottery to sell) are valid.

A Cusi's Sukah - if it is build correctly, it is valid; if not, it is invalid. (We do not rely on the testimony of the Cusi if he says that it is built correctly. The Cusis converted under duress and their conversion status was doubtful.)

One who builds a Sukah for himself should recite the blessing - "Blessed...who commanded us to make a Sukah".

If he builds it for others he should say "...[who commanded us] to make a Sukah for His name".

When he enters to dwell in it, he should recite the blessing - "...who commanded us to dwell in a Sukah".

Once he has recited the blessing on it on the first night of Sukah, he does not need to recite the blessing again (as the entire festival is considered one day).

Chanin bar Ba quoting Rav: The blessing of "Shehecheyanu" should also be recited at the time of building the Sukah.

Query: If a person did make the blessing of "Shehecheyanu" at the time of building, must he recite it again when nightfall arrives and he enters the Sukah to recite Kidush on a cup of wine?

Answer: Rav Hoshiya/ R. Ila/ R. Zevida all require him to recite the blessing again.

R. Chiya bar Ada quoted this ruling in the name of others - R. Zeira/ R. Yitschak bar Nachman quoting R. Hoshiya/ R. Yehuda bar Pazi quoting R. Chamah the father of R. Oshiya - after nightfall, he must recite the blessing again.