text:  Well, as I take each step, I'm trying to go and see if I'm doing everything correct. Could there be anything else that I'm missing, or am I assuming that the smell is coming from under the house up into the first floor? Well, I mean, the only other typical source of smells in houses is plumbing smells. So sometimes you get biogas in the drains of your sinks or your tubs. That can cause an odor. But if you clean those out with, like, an oxygenated bleach, that will keep that under control.