Why have the tiles cracked?

[Dave]

Substrate problem. If your floor is wooden floorboards I wouldn't tile the floor unless it's been cross lined with not less than 10mm ply screwed (not nailed) down with screws every 15cm minimum. Boards beneath need to be thoroughly fixed on the rafters too. Anything less the adhesive will crumble away due to deflection issues (as above) and the tiles will crack. In short...wood is flexible and tiles are not so you need to make the wood thick and strong to stop the bending. This will make your bathroom floor 20 to 25mm higher than the board level and many people don't like that.

Morning steve. It’s now not advisable to tile too plywood now , a change to bs5385 around 3 yrs ago i think now. Too much inferior Chinese plywood lol.

 

[benchwarmer]

Substrate problem. If your floor is wooden floorboards I wouldn't tile the floor unless it's been cross lined with not less than 10mm ply screwed (not nailed) down with screws every 15cm minimum. Boards beneath need to be thoroughly fixed on the rafters too. Anything less the adhesive will crumble away due to deflection issues (as above) and the tiles will crack. In short...wood is flexible and tiles are not so you need to make the wood thick and strong to stop the bending. This will make your bathroom floor 20 to 25mm higher than the board level and many people don't like that.

10 mm ply will still expand and contract,as you've just said "wood is flexible" so why cover it with more wood? Wow!!! It's not all flexibility, it's expansion and contraction, that's why tilers don't use it! This guys floor is completely nackered because of substandard multi traders following substandard advice, and the argument of "well I've never had a problem “is mainly due to the fact that people will not allow monkeys back into their homes and would rather go elsewhere. Please stop posting now before you ruin any more homes mate 👍🏻and leave the tiling to the tilers.

 

[Jon_Hall]

Morning steve. It’s now not advisable to tile too plywood now , a change to bs5385 around 3 yrs ago i think now. Too much inferior Chinese plywood lol.

Hi Dave the part of BS5385 you're referring to is, that plywood not recognised as suitable substrate for wall tiling, hopefully it will be the same for floors too, in the not to distant future. However I totally agree that there are far better options for suspended floors, that are more rigid and not subject to thermal movement.

 

[Dave]

Hi Dave the part of BS5385 you're referring to is, that plywood not recognised as suitable substrate for wall tiling, hopefully it will be the same for floors too, in the not to distant future. However I totally agree that there are far better options for suspended floors, that are more rigid and not subject to thermal movement.

I haven’t used ply for many many years Jon. Too much to go wrong. Did think it included floors lol. But must admit it should include both.