Installing slate over painted block fireplace
Help!! When our housing tract was built in '64, the fireplaces were built of concrete blocks (like fences) and were painted and have been painted several times over by several homeowners. Our neighbors hired a contractor who chipped the paint off and installed slate tiles. This was a very expensive, messy process, and the surface isn't as flat and smooth as I'd like to see considering the expense/mess. I'm wondering about the alternative of plywood or backerboard installed directly over the existing painted block and installing the slate on that. Which of these would be preferable? Would it matter (plywood is cheaper and lighter)? I could save myself tons of money and mess doing it this way myself, but would like some advice on whether either of these bases would be sufficient, and which would be best.