I have a large back porch that is roof covered, I store my GS under it and roll it out onto the uncovered area to cook. However, in the rain, or snow, I often fire up the pit and keep it under the porch roof. That is not very often. No problems so far, and very little soot, since the prevailing winds usually carry the smoke away. I will take a closer look at the ceiling after the comments from others.
Would be nice if you had a pad to roll yours out on for the low slow cooks.