Hello,
I have what I believe is a plastered chimney breast with old wallpaper remnants. I'm considering buying adhesive and putting up a 90mm fire-resistant gypsum board over it, then regular gypsum board on the sides (after removing the awful masonite). I briefly spoke with a chimney sweep today who claimed that regular gypsum is just as good; can that really be true? When I light a fire—which I do daily—I can hold my hand against it without burning myself.
Then I'm thinking of sealing the existing plaster with tile adhesive, or is it better to buy real plaster (gypsum plaster?) instead? I've never used it before, but as they say, there's a first time for everything.
I'm a bit worried that the plastered wall isn't completely even, partly because the masonite that was there before wasn't entirely smooth. Do you think this is difficult to fix and/or would it take a long time if I hired someone to do it?