Even if you install the correct type of drywall or plaster, you can still have a mold problem on the ceiling or walls of the bathroom if the insulation is not installed correctly. In the winter months, the moist air from the shower can condense on the walls or ceiling if there is inadequate or missing insulation.
Solution: Keep your bathroom dry
The best way to prevent moisture build up is to install a bath fan. A typical bath fan alone is not going to suffice it you took a 30 minute long shower and the bathroom is full of steam. You leave the bath fan running for at least 15 minutes after you exit the shower. A timer switch is a great way to make sure you leave the bath fan on and have it shut off in order to save energy. Manufacturers such as Panasonic have models that have a sensor and automatically come on when you enter the room and can be set to run for a short period after you leave so you don’t have to worry about using the switch or the timer switch.
If you have mold growth on either the drywall or paint, then covering up the mold is not the solution. In many cases the mold has taken a foothold in the drywall or ceiling tiles and will need to be removed and replaced. Using a professional mold remediation company is recommended since they know how to properly handle the contaminated material without spreading it to other parts of your home.