There's a musty smell in the bathroom that's been getting worse, and I finally found the source—black mold is spreading behind the drywall right where the shower pipe enters the wall. The leak from the plumbing fitting has been slowly soaking the sheetrock, and now there's a damp patch with fuzzy growth creeping along the bottom edge. I need to cut out the damaged section, fix the pipe joint, and replace the drywall before the mold travels further. mold behind drywall near plumbing 39