Grout Cracking despite rakeing it out and doing it again

[Flintstone]

Almost certainly movement in the floor. How thick was the ply? Tiling onto any wood is best avoided. If you start as you mean to go on an refuse to tile onto ply, you will have a lot less issues. Cement board is far better. Can’t comment on what’s under the ply

 

[Weebisto]

Almost certainly movement in the floor. How thick was the ply? Tiling onto any wood is best avoided. If you start as you mean to go on an refuse to tile onto ply, you will have a lot less issues. Cement board is far better. Can’t comment on what’s under the ply

Really good advice thanks

 

[Ajax123]

Large joints heating on full bung.... recipe for drying shrinkage cracks

 

[Weebisto]

Large joints heating on full bung.... recipe for drying shrinkage cracks

Thanks for that @Ajax123 I'm fairly early on in terms of experience but it was one of the few variables that was different to anytime before and grout has always dried nicely up until now. And heating was on full bung as I lost 3lbs which helped the diet!

 

[Time's Ran Out]

Heating on full bung - that in itself should cause concern.

 

[Perry]

A heated floor?

 

[Tile Marble Granite]

Dont walk on it. It will not crack, lol

 

[Qwerty]

@Weebisto correct me if I'm wrong, but you dont seem to be having too much luck with tiling!? At the start of the month you posted this thread-
After a knock to confidence, back at it tiling a floor - https://www.tilersforums.com/threads/after-a-knock-to-confidence-back-at-it-tiling-a-floor.85106/#post-890700

and said in there .....

Back in the saddle this week with an ensuite floor that needs old adhesive removed, backer board installed and sealed then tiled. Using Mapei Keraquick with 100% coverage and will be working from a centre point and using tile levelling system.

Any words of wisdom? This one has to go well

Why did you chose to tile to wood when you knew backer board was the correct method. There was plenty of pointers for you by members in that post.

My advice to you is to know your limits and proceed with tiling with caution. You have had problems with a couple of jobs now and run the risk of doing your reputation more harm than good. This latest floor will keep failing (with movement) and you will have to take it all up and start again. But who will pay for this, you or the customer?

 

[Bathfix Bob]

[Distant sound of gunshot]

I know the last time i tiled on plywood floor it failed and that was 2010, I did tile an 18mm plywood countertop for a basin this year and due to thickness constrains I couldn't add another 6mm so i had to tile straight to the ply and i remember the grout cracked as soon as it dried with no weight on the countertop.

God knows what that was all about.

 

[macten]

What's Mapei latex sealer?

 

[GAZ5518]

Cracking probably due to either movement or delamination...I will always prime floor at least twice and then Bal rapid mat on any ply I come across failing that 6mm hard I backer or the like...
Flexible adhesives and grouts whilst a must, can only deal with a certain amount of deflection etc..
Once again ....as the others will tell you ...preparation is key...