Cracking or peeling paint in a bathroom signals that moisture levels have risen out of control. Simply repainting without making changes will not solve the problem, but starting over with clean, well-primed walls and repainting correctly will. The problem will not return as readily if you then control the excess moisture and keep a watch on the humidity level.
Bathrooms contain more moisture than any other room, making it important to properly ventilate and control excess moisture with an exhaust fan. The moisture and dirt and soap buildup from showers and baths can seep into the paint and break its bond with the wall, causing peeling and cracking. To keep moisture from building up, aim to maintain your home’s relative humidity -- or balance of temperature and moisture -- below 50 percent, most importantly in the bathrooms. You can buy a simple humidity meter for a few dollars at a hardware store to keep track of the level. Installing and running the right size ventilation fan in every bathroom can help remove much of the moisture that can cause paint to peel.
Even if the walls appear clean, take time to prepare them correctly before painting. Remove all visible flaking paint, and sand down walls where the paint flaked to avoid uneven spots in the new paint job. If you leave any dirt or oily residue, you can almost count on peeling paint -- because the new paint cannot adhere properly on a soiled surface. To properly clean the walls, use a powerful cleaner containing trisodium phosphate, and completely rinse it before letting the surface dry. Glossy paint on the walls requires sanding or treatment with a deglossing product before repainting.
To give your bathroom walls the best shot at looking good for years, stall the effects of time by properly priming the walls before painting them. A top-quality primer will prevent paint from hardening, which causes cracks and peeling. Examine the drywall to see if it needs patching before applying primer. If you cover areas of damage, a primer designed to repel stains works best. While paints formulated especially for bathrooms exist, regular glossy varieties do as good a job repelling future moisture.
Realize that all paint eventually fails and will need touch-ups or repainting. To ensure top quality, do not use old paint stored since an earlier use, especially in a shed or garage where it could have frozen and thawed, which hurts the quality. Watch for walls with several coats of paint, which in itself can cause peeling. Strip the paint if thick layers threaten success of your planned paint job.