I live with two roommates in a flat. One of them smokes. Of course, he has to smoke indoors as well, as if the whole place is his (we got two balconies btw) . Can't describe when I get home after a long day in uni to come back to a flat that smells like a smoking friendly bar.
I feel like this should've been discussed before moving in together. Still not too late to talk though - if he's even a little bit considerate, he'll agree to only smoke outside.