Daf Yomi - Sukkah 12 - Sukkah = S'chach

Rabbi Yochanan cites a source regarding the two halachos of s'chach. The possuk states that the s'chach should come from the excess of the granary and from winepress. These are things that grow from the ground and are not susceptible to tumah.

Rashi in the Mishna states that this halacha is only relevant to the s'chch and not to the walls. The Torah states that the sukkah should be made from these materials and the sukkah is referring to the s'chach. The requirements of three walls, which is also learned from this possuk is only from the extra words, however the word sukkah is defined by the s'chach. This is why bundles of straw cannot be used for s'chach but may be used for the walls.

A question can be asked on the Rambam as to why regarding the halacha of deriving pleasure from the sukkah are the walls included as well? This prohibition is also learned from the possuk chak hasukkos and that is why the Rosh rules that only the s'chach is forbidden and not the walls. What is the explanation in the Rambam?

There are acharonim that address this issue.