Cracking grout

[DinkyD]

I had my kitchen floor 'professionally' tiled but the grout is cracking and has come loose in loads of places. The workman used powdered grout mixed with water and although I have tried to refill the gaps myself, mixing the grout accoding to the instructions on the packet, the same keeps happening. What has gone wrong and how can I fill the gaps now? I would be grateful for any advice.

 

[gcol]

Welcome to the forum.
I'm assuming here that the subfloor was floorboards here. It could be a few things - this is what might have gone wrong in order or likelyhood:

1. Tiler did not overboard the floorboards.
2. If the tiler did overboard the floorboards, he did it incorrectly or used the wrong thickness of ply.
3. Tiler did not use flexible grout.
4. Dodgy batch of grout.

Have you spoken to the tiler?

Have a look at the sticky for what preparation the tiler should have done to before tiling.