There are a lot of ways that a ceramic tub surround wall tile can get cracked. But, if the crack runs along the entire length of the longest tub surround wall, then there’s only one explanation — whoever installed the original tub surround used concrete backerboard (good) but jammed the backerboard seams so tightly together that they couldn’t expand or contract without cracking the tile above (bad).
Whether it’s a single tile or a whole row, here’s the thing about cracking out and replacing cracked ceramic tiles — the process generally creates still more cracked and chipped tiles.
Ceramic tiles are very brittle. And, with tight grout lies between tiles, any stress that’s put on one tile gets easily transmitted to all the adjacent tiles. So, here’s what generally happens when you try to remove just one row of ceramic wall tiles in a tub surround.
First, it’s a good idea to use masking tape to try and isolate the stresses:
As you can see in the picture, it’s also a good idea to really thoroughly mask off the tub itself and any ceramic fixtures (like wall-mounted soap dishes) that could be dinged or chipped by falling tiles. You don’t want your ‘fix’ to create more problems.
Second, you’ll want to remove the cracked tiles by cracking them more. Smashing the cracked tiles to bits before chipping them out of the wall will reduce the stress on the surrounding tiles.
But, only so much. Here’s a better than average result from removing ‘just’ one row of cracked tile on a ceramic tile tub surround:
It’s kinda like pulling a single thread on an old sweater — likely result is more threads coming out than you expected. But that’s okay. Just get more replacement tile than you think you’ll need, and that’ll be just about enough.
Then, you can install the replacement tile (this time using modified thinset to ensure that the surface tiles won’t crack even though the backerboard seam is too tight):
Then, using a few tricks of the trade to blend the new grout seamlessly with the old, you can get a completely seamless result!
Can you spot the repair? Of course not. Yay tricks of the trade!