My Sukkah has a Schach mat made of wooden slats and is tied to the sukkah with nylon. Is this kosher Lechatchilah?
The Ma’amid (what the Schach rests on or what’s holding down the Schach) should Lechatchilah be from something that is Kosher for Schach. Nylon, however, is Mekabel Tumah and therefore invalid for Schach. Therefore, it should not be used Lechatchilah as a Ma’amid.
However the Halachah of Ma’amid being kosher for Schach is only a Lechatchilah. If it was already made like that, one can eat in the Sukkah even if another Sukkah is readily available.
However, if one puts 2x4s of wood on top holding down the Schach and the mat will stay even without the nylon, it can be placed like that even Lechatchilah.
.ראה שוע”ר סי’ תרכט סעי’ ז-ט והנסמן בפסק”ת שם ס”ו