Is there a bubble-like bumps on your wall?
What is it?
These bubble-like appearances are caused by blistering, which happens when certain areas lose adhesion, forcing the paint film to lift from the surface.
Possible Causes:
Due to trapped moisture or gases in paint film (more likely in enamels).
Painting under direct sunlight or on surfaces that are too warm. This is especially true if the coating you’re using is dark in colour and solvent-based.
Applying an oil-based finish on a wet or moist surface.
Exposing water-based finishes to dew, high humidity or rain immediately after the paint has dried. This becomes a greater issue if the surface has not been properly prepared at first, or if the quality of paint is poor.
Solutions:
Scrape and sand blisters till they go away and then repaint it.
Remove sources of moisture. Repair loose caulk and install vents and exhaust fans wherever possible.
Prime and paint the wall with a high quality water-based exterior paint.
