By Paul F.P. Pogue, Angie's List Mold and rot are dangers that can develop anywhere in your house. But the bathroom, which generally contains more moisture than any other room in the house, is a particularly ripe target. Mold and rot can cause health problems and do serious damage to your house, so itâs best to take steps to prevent them. The first signs of mold are darkened wood, water stains on your ceilings and water marks around bath vents. When you detect mold in your bathroom, you should address it quickly, before it spreads further. Pay attention to exhaust fans and vent ducts, where condensation will frequently collect.