Prepping your walls and ceiling before painting is an extremely important step to ensure your bathroom looks its best. Properly done prep work will ensure that your paint does not bubble, become mouldy or mildewy over time. Fortunately, this work can be done in just an afternoon, but it is important to have proper ventilation in the bathroom before you begin. Taking a few minutes to open all the windows and doors will help the paint dry quicker and prevent you from inhaling paint chemicals.
Examine the integrity of your walls and ceiling. Look for cracks, holes, bubbling paint or other signs of damage.
Use bleach diluted with water (about 1 tablespoon per 4.5 litres) to wash your walls. If you see any signs of mould or mildew, use a stronger bleach solution or pure bleach to remove it. The bleach will kill the mould and other bacteria. Be careful when using this solution on the ceiling. Wear goggles and a face mask to avoid injuring yourself.
Use a paint scraper to remove thick layers of paint from cement walls or bubbling paint. Bubbles under the paint are signs of trapped moisture and in some cases can indicate a leak. They are particularly worrying if seen on exterior walls and roofs because they may indicate the ceiling is giving way, so contact a professional repairman if you observe these issues. Use the scraper to remove all of the paint from the walls and ceilings. If the paint is smooth and shows no signs of damage, do not scrape it off.
Sand the walls that are not damaged by water or mould. Also sand areas with cracked paint or holes in the walls. Sand until the wall is smooth.
Fill the holes in the walls and cracks in the ceiling (after ensuring they do not indicate structural damage) using a filler or plaster. Sand the filler smooth after it has dried. The drying time will vary depending on the brand, so check your product's packaging.
Paint the walls with a coat of primer after you have cleaned and smoothed all the walls. Look for a primer made specifically for bathrooms because these are made specifically for damp environments. Your bathroom is now ready to be painted.