I'm installing a stone back splash behind my bathroom sink - 16 SF. The wall is currently painted and I want to make sure that the stone and thinset adhere properly. Should I sand the wall with 80 grit sandpaper and apply the thinset/stone or should I put 1/2 or 1/4 plywood down for better adhesion? Perhaps cement board?
Ideal way is to do a cement board as a backer board but since its in a non wet area,( not exposed to direct water) you really don t have to.Roughing the area up is always a good idea and won t hurt a thing. I d never do a wood backer in a moist and humid environment, It can expand from moisture and break the bond. Any questions you can e amil me through my avatar and check my qualifications there. GL
May 11, 2017
Your tile man is right. The primer may fail and then your tiles will come crashing down. Which costs more, the cement backerboard or the tiles? Why did you paint it? And why did you use drywall compound on the patches? The paint is not compatible with cement, and the drywall compound is just some ground minerals and water or a little vinyl admix. If you can carefully remove the cement board, you may be able to reuse them by flipping them over. Use a stiff scraper and get the compound off the joints, and then the tip of a screwdriver to open the screw heads so you can remove them.
May 11, 2017