What should I use to fill gaps between plywood?

[pharmjoi08]

I had my bathrooms tiled a few years ago by someone who didn't do a great job, anyway I noticed I had three cracked tiles with a hairline crack all the way down.

I've taken the tiles up and realised there's a gap between the plywood that matches the crack (see photo). Is there anything I can use to fill that gap before replacing these tiles?

 

[JP_]

Are the two boards level? I'd assume the crack in the tiles would be because the boards are no level, not because of the gap.
Reboarding might be the only option.

 

[pharmjoi08]

Are the two boards level? I'd assume the crack in the tiles would be because the boards are no level, not because of the gap.
Reboarding might be the only option.

They are level, gap seems to be the culprit

 

[Captain Nemesis]

Cant you see what a state those boards are in?

I had my bathrooms tiled a few years ago by someone who didn't do a great job

Including not using the right material to tile onto.

Is there anything I can use to fill that gap before replacing these tiles?

I wouldnt just replace them.

Removing the rest of them and reboarding with proper backer board would be favourite.

 

[pharmjoi08]

Cant you see what a state those boards are in?


Including not using the right material to tile onto.



I wouldnt just replace them.

Removing the rest of them and reboarding with proper backer board would be favourite.

Yes that would be the perfect option but would entail retiling 3 bathrooms. Not something I feel particularly keen to do right now...

 

[foxhole]

I had my bathrooms tiled a few years ago by someone who didn't do a great job, anyway I noticed I had three cracked tiles with a hairline crack all the way down.

I've taken the tiles up and realised there's a gap between the plywood that matches the crack (see photo). Is there anything I can use to fill that gap before replacing these tiles?

The ply is getting wet causing movement as it swells, cracking the tiles, repair and it will happen again.

 

[Lower]

They are level, gap seems to be the culprit

The two pieces of ply are moving relative to each other, hence the crack.

A proper fix would be to replace the ply with a proper rigid tile substrate, but that would mean replacing the ply. You might get a way with a flexible tile adhesive but its always going to be a weak spot.