Q. If one has a plastic cover over the schach when it rains is it better to eat in the Suka or in the house?
Thanks

A. According to the opinion of HaGro (629: 5, see also Maase Rav 217) mentioned in the prior answer, that while it rains a suka in not considered a suka at all, there would be no point in sitting then inside the suka. However there are different points of view and some would consider sitting in the suka as the better option since according to the opinion of Rabenu Tam the plastic cover, albeit the fact that it is non kosher schach, it would become nullified by the kosher schach if it is within four tefochim of it. (Kuntres Ohr Yisroel p. 124, See also Shoshanas Yisroel, 8 note 32.) Emek Hatshuvo (2: 57) advises using a clear plastic shlack (cover) that lets the light of the sun pass.

Horav Shlomo Miller’s Shlita opinion is to follow the ruling of the Mishna Berura (629: 58) that recommends placing a sheet to protect oneself from the dripping rain. However a plastic tarp or cover that does not permit any water to pass would be seen as a house roof and would not be nullified to the schach.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a.