I am finishing the basement in my 1926 house and planning to frame a proper wall against the concrete foundation - studs, insulation, moisture barrier, etc.
The previous owners had painted over the concrete foundation, and I noticed a fair bit of efflorescence coming through the paint, so before I framed I planned to scrape off the efflorescence where I saw it, treat it with a cleaner for efflorescence, paint it over with dry lock, and then do my framing.
As I scraped it, chunks of the wall peeled off fairly easily - I can't tell if it was just a thin layer of drywall or concrete backerboard, or actual concrete / plaster bonded to the paint (you can see it in the photo). The discoloration in the wall and removed chunks worried me a little, as well as the fact that some of the darker chunks that you can see in the photo were pretty soft, almost like wet cement / dirt, so I'm wondering if I need to do more than just what I mentioned above. Should I be scraping clear the whole wall? Is additional masonry work needed first? Any advice would be helpful.