Im in the middle of a renovation and the tiler has told me that Natural stone tiles 18x18 should not be installed on a cement board wall that has been primed. This application is for a shower/steam room. He has told me that i should rip down the cement board and replace with new unprimed boards. Any advice. The tile is planning on using Flextile 52. Please advice if the boards need to be replaced. The cement board has had the screws and joints covered with drywall cement and then the entire wall was painted with drywall primer sealer (latex).Thanks
from what ive heard, the mortar wont bond to paint properly
you will be fine. if you want take a steel brush and brush some of the primer if the tile guy is that persistant
Use Hardibacker and seal the seams with tape and thinset. Use thinset to set the tile using 1/4 spacers. I have used and recommend that you use a tile sealer to seal the slate prior to grouting and to use epoxy grout. The grout is more difficult to install but requires no sealers which need to be redone at least once a year in a shower and is well worth the initial time and effort. Be sure to read and follow the directions on the grout bags to ensure a uniform color and good grout set. MT C
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.
You can do it, but you shouldn't. Especially not in a shower. The primer will prevent the mastic/mortar/thinset from adhering to the cement board. Drywall compound should not be used in cement board for a tiling application, a fiberglass mesh tape and thinset to reinforce the joints, and the thinset will covewr the nails. Your best bet would be to do as the tiler says (I know that the cement board isn't cheap, but would you rather have the tile come crashing down on you in the middle of your shower?), though you may be able to remove enough of the primer and compound through muscle power. (buy a decent dust mask. silica dust and fiberglass are no fun to cough up) Another alternative, go over the offending cement board with another layer of 1/4 inch cement board, staggering your joints between the layers. Run this by your tiler, he may agree... if nothing else, the staggered joints will lessen the chance of the joints cracking.
