Why does mildew grow in caulk, grout and on the ceiling?
Mildew grows in grout because it is a porous surface that is constantly wet. Mildew is also often found on bathroom ceilings because of poor ventilation and a ready supply of food and moisture. In addition, mildew can grow behind caulk if its airtight seal has been broken. Unfortunately once mildew moves behind the caulk, it is hard to penetrate with a cleaner and may require removal and a fresh caulk application. If fresh caulk is applied, the area should first be prepared with a bleach solution.
