Repairing bubbling (blown) plaster on an interior wall

Question

I have no idea what kind of wall this is. Both my walls that are near radiators have this bubbling plaster look. I have read that painting with temperature differences may cause the bubbling (such as painting in the winter and then the heater is turned on). It was recommended to paint in the summer when the windows can be left open to equilibrate the temperature as the paint dries.

Not sure what to do about the bottom. How do I repair this wall? It seems to be paint --> very thin layer of plaster --> concrete. Does the whole wall need to be taken down? Should I just scrape off the plaster and respackle? I was thinking of sanding down the bubbles, respackle, and repainting. Does the whole wall need to come off?

Bottom of wall

Top of wall

Answer 1

I suspect that it is caused by moisture migration through the plaster. I would definitely scrape off the damaged paint and sub material first. Check for moisture, better to use a moisture meter if possible. Look for other areas below the floor for any evidence of water infiltration. May have been a one time thing, but I would be looking for the root cause, which I think may be water. Once you are satisfied the area is dry, remove all loose or crumbly plaster down to a solid base. If the voids are deep, I would use a thinset, setting type filler first, then a Spackle or drywall compound to get a smooth finish.

Answer 2

I'd second Shirlock...that appears to be a moisture problem. Is the plaster bubbling, or just the paint?

Are those solid concrete walls? If not, I don't think that's concrete you're looking at, but traditional old-school plaster. Plaster was put on in two layers...scratch coat and finish coat.

If it's just the paint, and ALL layers of paint are pealing off as a whole, I'd say the issue is moisture. That can be a much different beast to remedy.