Paint Incompatibility
This refers to the loss of adhesion that may occur when a water-based topcoat is applied over several coats of old, solvent-based paint.
POSSIBLE CAUSES
Using water-based paint over more than three or four coats of solvent-based paint may cause the old paint to lift off the substrate.
SOLUTION
Repaint the surface using another coat of solvent-based paint. Or, preferably, remove the existing paint and prepare the surface by cleaning, sanding, and spot-priming where necessary. Then paint the surface with a top quality water-based exterior paint.