Symptoms
- Black, green, or dark spots on the wall surface
- Musty smell in the room
- Spots often near windows, bathrooms, or exterior corners
Likely causes
- CommonCondensation on a cold wall surfacePoor insulation or ventilation can let moisture condense and grow surface mold.
- CommonHigh humidity in the roomBathrooms and kitchens without enough ventilation are prone to surface mold.
- PossibleHidden leak feeding the moldMold that keeps returning in the same spot despite cleaning often means moisture is still getting in.
What to do
- Identify whether the spot is on the surface (paint) or has soaked into the drywall itself.
- Ventilate the room well, opening a window or running a fan.
- Clean small surface mold with a solution of water and mild detergent, or a diluted bleach solution on non-porous painted surfaces.
- Let the area dry completely.
- Improve ventilation in the room, such as running a bathroom fan longer or using a dehumidifier.
- Repaint with a mold-resistant paint if the area is prone to humidity.
- Monitor the spot over the following weeks to see if it returns.
Tools and parts
- Scrub brush or sponge
- Spray bottle
- Dehumidifier (optional)
Mold-resistant paintSearch: “mold resistant bathroom paint”
When to call a pro
Call a mold remediation specialist if mold covers a large area, keeps returning, or if anyone in the home has respiratory sensitivities.
Safety
Use caution
Wear gloves and a mask when cleaning mold, ventilate the area, and never mix bleach with ammonia-based cleaners.