Painting - re-painting interior concrete walls

all main level walls are made of sealed concrete- I purchased this home 4 years ago-the walls are bubbling; crackling off chunks of paint-several layers. How do I repair holes; obvious cracking off of years of different colored paints; and bubbling sections- to smooth walls-then re-paint (with semi-gloss?)

I felt devastated when my plaster walls started to do the same thing in my hallway a few days after I painted them.

Things to consider about the failure of paint when it bubbles and cracks and peels off of the walls: anything new happening? The paint was there when you moved in? New roof? Gutters OK? Did this just start out of the blue or was it there when you moved in?

These problems can be from two sources as come to mind. 1. Moisture intrusion through the walls. The would cause cracking and peeling by itself. Moreover, the moisture can react with the materials in the concrete causing the surface to detriorate and the paint to fail. Sources of moisture can include leaks in roofing and gutters. Water overflow from blocked gutters and downspouts. Water from leaking pipes in the wall or wall and floor overhead. Water overhead can come from bathrooms, tubs, sinks, and drain pains under appliances in the upper floors or attic.

2. Another potential problem is contamination of the walls. If you have not recently painted these walls, like in past 6 months, it seems unlikely.

Pull off the failing paint and look at the concrete surface beneath. Is there evidence of any powdery substance; damp, slick area; or mildew? Does the original seal appear to be intact? It looks like a thick coat of wax making the concrete somewhat shiny, unless it was sealed with something akin to UGL masonry seal which is usually white. In short, you should not be seeing bare concrete. Put a dab of water on the surface, if it soaks in right away, it tends to indicate that there is bare concrete present.

The reason for going through all of this is that there is no point in repainting until the source of the failure is discovered.

If you can rule out water as the source of the problem, that leaves contamination at the layer where the paint is failing. That was the problem here.

Once the problem is solved, scrape off all the paint that will come off. Clean the walls with TSP or spic and span, and rinse thoroughly. Prime the walls with Zinsser 123 or its equivalent. You can fill the depressed areas now with a thin coat of drywall compound and sand smooth with some 100 - 150 grit sandpaper. Prime over any repairs that have been made and paint with a top quality latex paint.

Finding the cause of the problem is the key.

Hope this helps.

thank you for your reply. i will try what you say; sounds like good advice!