Blistering: describes paint that bubbles on the surface. It is an early sign that more serious problems, like peeling, may be forming.
Causes: Blistering can result from poor preparation or hasty application of primer or paint. The blisters are caused by trapped moisture as it forces its way through the surface.
Solution: Scrape and touch up localized blistering. For widespread damage, remove paint down to bare wood, then apply new primer and paint.
Peeling: occurs when paint disengages entirely from the surface, falling away in flakes.
Causes: Peeling is most often associated with persistent moisture problems, generally from a leak or a failed vapor barrier.
Solution: Identify and correct any moisture problems. If the peeling is localized, scrape and sand the damaged area only, then touch up with new primer and paint. If peeling is widespread, remove the old paint down to bare wood. Apply new primer and paint.
Alligatoring: is widespread flaking and cracking of surfaces, typically seen on old paint and surfaces with many built-up layers of paint.
Causes: alligatoring can be caused by excessive layers of paint, inadequate surface preparation, or insufficient drying time for a primer.
Solution: Repainting will not permanently cover significant alligatoring. Remove the old paint down to bare wood, then prime and repaint.
Detecting the Source of Moisture Beneath a Painted Surface
Localized blistering and peeling Indicates that moisture, usually from a leaky roof or gutter system, is trapped under the paint. Check roofing and gutter materials to find the source of the leak. Also look for leaking pipes inside the wall. Correct the moisture problem before you repaint.