Good Afternoon everyone. So a few years ago I renovated my kitchen. A lot of plumbing work had to be moved around in the wall and ceiling which also affected the upstairs bathroom. During the plumbing work the back of the upstairs vanity was cut open and never sealed back off. Now every once in while when someone takes a shower upstairs a sewer smell comes from the open space left in the vanity. I am finding no moisture on the ceiling or floor where the main drain line comes through the kitchen wall but I am wondering what to do.