Q. Can one make a suka by placing schach on top of an opening on the roof of an igloo?
A. Shulchan Aruch (O.H. 634: 2) rules that a sukka could be circular as an igloo is as long as it has the right size (contain a square of seven by seven tefachim area). Therefore, the circular igloo shape should not be an issue.
However, the fact it is made of snow or ice walls is detrimental and renders it unsuitable for a sukka.
A mechitza made of ice and snow, is not considered a wall for tumah purposes (Ohalos 8: 5). Poskim also maintain that proper mechitzos and fences of an eiruv surrounding a city that were covered by a high snow accumulation, do not disqualify the eiruv, since the snow is only temporal. (Noda Basheorim 2: 5, Zekan Aharon 2: 20, Sheilas Yaavetz 7, et al.).
Similarly, Shaarei Teshuva and Beer Heitev (626 :1) quoting Ginas Verodim rule that one may use a sukka covered with snow.
Therefore, Horav Shlomo Miller’s Shlit’a opinion is that an igloo or any other structure that is made by using ice or snow walls, should not be used for a sukka.
See question 2035 regarding placing a mezuza on an igloo.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit’a