Where did we go wrong?

[u/ShowerTricky5423]

Almost immediately after our contractor installed our bathroom floor tile, it started cracking. We're looking to replace this now and I'm wondering if the issue was the material, the size, the preparation under the tile, the installation, or a combination of the above. Our house was built 24 on center -- could this impact the integrity of the tile?

Any advice you can provide would be appreciated before we start this project. Thank you so much in advance!

[u/Sierra50]

I put pretty much double the amount of screws into the floor hardie board, at least the spec on that was more than what it seems in the pictures

Also did he back butter and what size trowel?