Smoke Detection: Smoke coming from the roof and floor usually indicates a possible fire hazard or venting issue, but in your case, it might be related to sewer gases escaping from a cracked pipe. Sewer Crack: Since you've discovered a visible crack in the sewer line under the floor, this could be allowing gases (and possibly waste) to escape into your building Camera Inspection: Yes, it is possible to inspect the sewer line using a sewer camera Locate the exact position of cracks or breaks. Identify any blockages, root intrusion, or misalignments. Assess the overall condition of the pipe.