Place tiles over uneven bathroom walls

I'm currently in the process of renovating my bathroom and putting tiles around the tub area. After installing cement boards on the walls I apply a think set suggested by the staff at the home improvement store. unfortunately, I found out the hard way that they suggested the wrong mixture after noticing that the tiles were about to fall off. I had to remove all the tiles from the walls (which was not so bad) but now I have an uneven surface to put the tiles on. I was told to even the area with the new adhesive. Does anyone know if this is a common approach? will this cause any issues in the future. I'm looking to other alternatives before i go ahead and replace the cement board.

 

What product did you use? If in fact a big box employee suggested a product that was not suited to the application and that's causing you problems complain to the store manager. If you have a legitimate gripe you may be able to get new tile, thinset and backer board out of them.

If I were doing the work I would probably just rip off the backer board and start over. Easier then trying to smooth hardened thinset.

 

Thanks cwbuff - I will take your advice and replace the backer instead of spending to much time trying to even the surface. I will also go after the store and try to get a refund for the damage products.