Plaster and backer board ceiling
So, I have a 1929 home and I'm ready to work on the ceilings that haven't been updated. Typical texturing, patches and cracks. It looks pretty bad. I watched some videos online about spraying with water and then scraping/peeling off. Well, I tried a section where there was already considerable cracking and sagging of ceiling material but it didn't seem to be the same material as in the videos at all. I seem to have plaster celings over concret backer board. Does this sound right? Why would the ceilings have such heavy material up there! IF it is what I described, what do I remove? Just the plaster? What do I put back over it and how?