We have a really bad sewage smell coming from a pipe in the basement, we were installing some new base board and had to go around a large metal pipe, about 6 inches in diameter, it smells REALLY bad. There is no dampness or water so I don't think it is cracked. Any ideas what could be going on? Thanks
awjw13

The pipe you uncovered is the main stack vent. This pipe should exit through the roof. Check in the attic to see that it does not terminate in the attic instead. Also check the upstairs toiulet. It could be leaking each time it was flushed into the subfloor and the odor from it stay in the chase the stack vent's in. It's for certain you have a leak or a open vent on this line. You just have to track it down. Good luck, Tom