Which adhesive and grout should I use for tiles over UFH???

[Strawberry57]

Hi there,

Can anyone advise me on which adhesive and grout to use over a wet underfloor heating system? There are 6mm plyboards over the pipes and we are laying 9mm porcelain tiles.
I wanted to use a grey coloured grout, do the tiles need sealing before using a coloured grout? (the assistant in Topps told me the coloured one tend to soak into the tiles)
Any help is appreciated

 

[Gazzer]

6mm ply is not good enough.

 

[Strawberry57]

Why?

 

[Gazzer]

6mm ply is way too thin. It should be 15mm minimum and screwed to floor every 200mm .....but really need to know more about your situation.

 

[Strawberry57]

oh okay. The UFH is Polypipe (overlay). There is no requirement for ply over the overlay, it is solid enough to lay tiles directly onto but my Polypipe installer recommended a thin ply to protect the UFH should we wish to change the floor tiles in the future.
We are ready to lay the tiles and I am buying adhesive and grout tomorrow. I know it needs to be a flexible adhesive but that's about it. Are they all the same??? Is coloured grout okay???
Sorry for all the questions but just want to make sure I purchase the most effective adhesive and grout

 

[Andy Allen]

6mm plyboard over pipes????

to thin to lay tiles to...

 

[Strawberry57]

The overlay heating system is 18mm it does not require ply over the top. The base itself is enough to lay the tiles on. The ply was put down to prevent damage to the system should we want to change the tiles in the future. We sought advice from Polypipe and had a recommended and experienced installer lay the system. It has been screwed dowtheory screws 20 cm apart.

 

[Tony73]

as above, 6mm ply not good. And you will have to use flexible tile adhesive and flexi grout

 

[bugs183]

Is this the system that sits on top of the floor and uses loose laid thermal boards with the u/f/h pipe clipped into them,ply boards are laid loose on top ,and then you are 'supposed' to be able to tile straight on top???

 

[Strawberry57]

Possibly, it's called overlay. Think the thermal boards are fixed though. There is a thin run for the pipe to sit into. The ply boards are screwed down on top but that was our choice you can tile straight onto the overlay.
Are my replies showing as I can not see them in the thread?

 

[bugs183]

I really am not a fan of these systems at all for tiling. They promise everything but are very flawed, awful advise given by the technical departments about methods of tiling them.
If i was going to tile it (and i would be reluctant) i would insist on laying the thermal boards that hold the pipes to the floor with flexible tile adhesive and screwing at minimum 200mm centres. Then i'd pour levelling over the whole floor to bond everything together, and then lay ditra Mat on top then tile. Minimum.
Do away with the 6mm plywood, it's a waste of time and WILL fail, the only reason you'll be wanting to replace the tiles is because if you tile on to 6mm ply loose laid on this system is because it will crack everywhere.
These systems move around way to much, one manufacturer says you can loose lay 6mm ply straight on top and tile this, no no no!
If any of these boards are moving you will have problems.

 

[nybor62]

totally agree with bugs , the method you are wanting to use is a recipe for disaster imho

 

[Strawberry57]

What's ditra mat?

 

[afright]

Ditra is a uncoupling matt made by Schluter giving you stress relief ,please listen to advice given on here,after all experience does count for a lot.

 

[bugs183]

Hiya Strawberry, here is Ditra from the Schluter site.
Schlüter-DITRA - Schlüter-Systems

It's completely up to you how you approach tiling your floor, but i really wouldn't skimp i'd 100% level and use ditra matting. It's really not worth the agro of replacing the floor.