Bag shaped blisters ranging from 0.5cm to 1m in diameter. Blisters can be intact or perished and flaking. If not dried out the blisters can be found to be filled with water/liquid.
Possible Causes
Excessive moisture ingress at back of paint film.
Painting too soon before the masonry structure has dried.
Water based paint exposed to rain; high humidity or dew shortly after the coating has dried.
Poor structural design aspect related to moisture barriers.
How Can I Fix This Problem
Remove all loose and flaking paint.
Establish cause of moisture ingress and rectify.
Allow structure to dry out before repainting.
In the event that the moisture source cannot be removed an ultra high PVC topcoat may have to be used.