preparation for bathroom floors with wet UFH

[andyq]

3 bathroom floors, all with wet UFH, currently have movement in them. Two of them have walk-in shower areas, grout has broken in many places, tiles have lost alignment, tiles move and some are so loose it wouldn't take much effort to get them up.
After the existing tiles are taken up what is the best way to prep the floors to avoid this happening again?
are we talking 22mm or 25mm marine ply on top of the wet UFH, then Ditra matting or some other decoupling membrane
before I fix in flexible addi?
Are there any grouts that are more flexible than others?

The sub floor under the UFH is timber

your advice is appreciated

andy

 

[White Room]

What sort of floor is under the tiles, chipboard etc...

 

[andyq]

I think its chipboard, I wont know for sure until I take a few up or speak to the builder tommorrow

 

[J Sid]

What is surrounding the wet ufh pipes? Any pics?

 

[andyq]

give me a few mins and ill get some photos up

 

[andyq]

got some more but you probable get the idea

 

[White Room]

I think your going to have to rip up and then evaluate the situation....

 

[andyq]

thanks for the replys, Ill speak to the builder tomorrow and find out exactly what he did

 

[Qwerty]

Not good. Looks as if laid straight onto chipboard. I can see the only way being a full rip out.
Sorry this has happened to you, not nice.

 

[White Room]

How long has the floor been down...

 

[andyq]

no it didn't happen to me, a builder i've just done a couple of jobs for, asked me to go and put a bit of grout on the floors!! I've told him grout is not going to fix this, it needs ripping up and starting again
I think when they have fixed the ply onto the UFH they haven't fixed it properly, maybe too few screws in case they hit the wet UFH pipes
I think the floors have been down about 12 months
I might be the one who gets the job to rip it up and redo, just wanted advice on how to prep it properly. I was thinking ditra matting ontop of new 25mm ply

 

[White Room]

Sounds like a thin ply may be the problem...if I know some builders.

 

[Ajax123]

Ply? Wet UFH? Sounds like a run screaming to the hills situation to me. Probably a much bigger job than you are anticipating I think...

 

[andyq]

yeah well whatever it is its got to be put right, I should know more tomorrow
How should a floor be prepared for tiling when its got wet UFH?

 

[Ajax123]

yeah well whatever it is its got to be put right, I should know more tomorrow
How should a floor be prepared for tiling when its got wet UFH?

You are no doubt right. I don't think you will know how much work till you take up the existing. So I guess optimism is the key.