Grout cracked few weeks after installation

[IHG_MAY]

In about 2-3 weeks after we got our bathroom fitted we noticed that the grout cracked along one of the walls over its entire length. The floor and other walls were done with the same tiles and grout but this joint is the only one that developed a crack. Attaching the pictures.

We had to replace the wall plasterboard as part of these works as it was too thin. The fitter put large 2.4m high pieces of plasterboard on the top part of the wall and a 30cm pieces on the bottom part. He then tiled the top part, then tiled the bottom part in a few days afterwards and then grouted entire bathroom. He didn't use any mesh or anything to cover the plasterboard joint.

The plasterboard joint is exactly behind this grout joint, so basically it looks like this ('x' ‐ tile, 'v' - half tile, '-' - plasterboard joint)

XXXX
XXXX
XXXX
XXXX
---------
VVVV

Do you think this is the reason why the grout cracked? Seems very plausible to me.

I haven't raised this with the fitter yet, what solution should I ask for? Remove the cracked grout and then re-grout? Is it likely to develop a crack again? Should he use caulk or Silicon instead? I'm concerned about the colour difference though.

 

[Dave]

Hard to tell from the pics , are those cracking joints around the same area as the board joints

 

[IHG_MAY]

Hard to tell from the pics , are those cracking joints around the same area as the board joints

Yes, the board joint is right behind the cracking joint

 

[Dave]

Yes, the board joint is right behind the cracking joint

Ok , you will have to remove tiles and sort the substrate.

 

[IHG_MAY]

Should the tiles be removed from both sides of the crack, or one side is enough (e.g. just below it)?

Also, could you please elaborate how the substrate should be sorted?

Thanks

 

[Phone-a-tiler]

Should the tiles be removed from both sides of the crack, or one side is enough (e.g. just below it)?

Also, could you please elaborate how the substrate should be sorted?

Thanks

Daves reply is correct. If wall sheets are fixed correctly then taping joints usually prevents this problem. Adding a flexible additive to new grout mix and raking out the old grout may work as removing tiles will probably damage the plasterboard and open up more problems.