Hello, I have a 15 foot wall that bears over the fireplace. My wife and I are going to replace the old tile around fireplace with slate. We've considered placing slate all the way up to the ceiling. Is this feasible,safe? My next question is whether slate can be adhere to drywall that has already been textured and painted? The stack has flat paint on it already. Can I just put mastic on the painted wall? Any input will be useful. BTW I am new to this forum and this is my first post so hello to everyone! Thanks. Ive attached the pic of fireplace and 15 foot wall stack.