I'm in the process of remodeling my bathroom and am about to start tiling in the next few days, I noticed that the cement board has a small valley about 1/8 of an inch on a 3x5 durock cement board where the shower head and faucet are. Can I level out the cement board with modified thinset to have a flat surface to lay the tiles on? I drew a super quick illustration:
I suppose it's a bit comical but I hope it's clear what I'm trying to achieve, it's not drawn to scale. I guess my fear is that the modified thinset doesn't bond well to the cement board and the tile weakens and eventually falls. I appreciate any advice.
Last edited by SlimCharles; 09-25-2012 at 11:28 AM.
Reason: picture url
Anytime you install cement board (or equivalent) you should first check the studs with a 4 ft level. Check for plumb and to see if all the studs touch the level evenly. If not then your supposed to pad it out with shims. Figure out where the inconsistency is and adjust accordingly. Where you find a gap on the level, use the thin end of the shim. Screw it to the stud so the backer board will be flush.
You can remove the cement board and follow this process to achieve a non beveled surface. If you dont wish to do this then i recommend setting the tile with different size butters. Use different sized notched trowels to pad the edges out. I would never recommend this technique for a DIYer because it is very difficult if not impossible for anyone to achieve perfection.