Related for Sukkah 1:11
הָעוֹשֶׂה סֻכָּתוֹ כְּמִין צְרִיף, אוֹ שֶׁסְּמָכָהּ לְכֹתֶל, רַבִּי אֱלִיעֶזֶר פּוֹסֵל, מִפְּנֵי שֶׁאֵין לָהּ גָּג, וַחֲכָמִים מַכְשִׁירִין. מַחְצֶלֶת קָנִים גְּדוֹלָה, עֲשָׂאָהּ לִשְׁכִיבָה, מְקַבֶּלֶת טֻמְאָה וְאֵין מְסַכְּכִין בָּהּ. לְסִכּוּךְ, מְסַכְּכִין בָּהּ וְאֵינָהּ מְקַבֶּלֶת טֻמְאָה. רַבִּי אֱלִיעֶזֶר אוֹמֵר, אַחַת קְטַנָּה וְאַחַת גְּדוֹלָה, עֲשָׂאָהּ לִשְׁכִיבָה, מְקַבֶּלֶת טֻמְאָה וְאֵין מְסַכְּכִין בָּהּ. לְסִכּוּךְ, מְסַכְּכִין בָּהּ וְאֵינָהּ מְקַבֶּלֶת טֻמְאָה:
If one makes his succah in the shape of a cone, [so that it does not have a roof], or if he supports it on a wall, [inclining the tops of the reeds to the wall, the reeds slanting downwards to the ground], R. Eliezer rules it pasul because it lacks a roof. [It is not clear what is roof and what is wall. For a slanted tent is not called a tent, but only one which has a roof of (at least) a handbreadth.] And the sages rule it kasher. [The halachah is in accordance with R. Eliezer.] A large reed mat made for reclining acquires tumah and may not be used for schach. For schach, it may be used for schach and it does not acquire tumah. [With respect to a small mat, there is no difference of opinion, all agreeing that it is made for reclining and not for schach (roof covering). Where do they differ? With respect to a large mat. The first tanna holds that a large one is made for schach and a small one for reclining. And his words are to be understood thus: A large mat is made for schach, but if he expressly states that he is making it for reclining, it acquires tumah and may not be used as schach. "For schach, it may be used for schach": This is to be understood as follows: And a small mat is made for reclining; but if he expressly states that he is making it for schach, it may be used as schach.] R. Eliezer says: Both small and large are made [ab initio] for reclining. [Therefore,] it [even a large one] acquires tumah, and may not be used as schach. [But if he expressly stated that it is] to be used for schach, it may be used as schach and it does not acquire tumah. [The halachah is in accordance with R. Eliezer.]