Tiling on underfloor heating warm panel

[Old Mod]

As Julian said above, just screw boards down to floorboards every 300 mm
These retro fit systems are often loose laid but boards glued together.
Typically the combined weight of boards pipes water and tiles is enormous, and movement isn’t expected, but always possible, hence mechanically fixing boards down.
From there, there are two recognised routes.
Either Ditra 25 and tile or
Pressurise system to 6 bar cold, cover with self leveller to 5mm over pipes, when leveller is cured release pressure and this will give small amount of space for pipes to expand and contract during heating.
Then cover with a 1mm antifracture Mat, such as time master and tile.
Tilemaster will spec tiling direct to the board with their ultimate S2 adhesive, but they prefer latex and antifracture mat.
Just make sure you use recommended primer on top of boards before any work commences.
And prime the leveller before tiling if you take that route.
They’re not a real concern if correct procedure is carried out.
The ones to watch are the polystyrene foam boards with aluminium foil on top, they’re bad news and originally designed for laminate, not tiles.

 

[Jon]

Thanks for all your responses. The way to move forward for me seems to be fixing the boards down to the 18mm ply. As the floor is level already I will probably not use self levelling compound on top if not necessary.

The manufacturing instructions then say:

“The boards must first be primed using Prime IT MSP. The tiles can then be secured on top using a suitable S2 flexible tile adhesive.

This seems to be consistent with what is recommended here. Would it make sense to put an antifracture mat on the boards before tiling?

Finally, I realise I am in well over my head trying to tile this myself so if anyone is or know a good tiler that fancies quoting for the job please let me know. We’re in London N16. Apologies if this is considered bad manners on the forum.

Many thanks again for all the answers!

 

[Old Mod]

It’s not bad manners Jon you’re fine.
If you would like to try and find someone suitable please start a new thread in the

FIND A TILER section.

Thank you.
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Incidentally the leveller is not actually for the purpose of levelling the floor.
It’s prime purpose is to fully encapsulate the pipework, whether it be adhesive or leveller, it must be done, and to allow for a good even transfer of heat between pipes and finished floor.
Also be aware that the first time heat is put thro the pipework when the floor is tiled, it must be taken thro the proper warm up and cool down process first, before normal use.
The purpose of this is to reduce the risk of thermal shock in the adhesive.
And if in the future it’s ever turned off and on, thro summer months for example, it must be turned off and on over a few days, slowly reducing or increasing heat. 2-3 days would be sufficient.
Thermal shock can happen at any time there is a fast change of temperature.
Like putting boiling hot drink on cold granite can crack a cup.
Nothing to worry about, just something to be aware of.

 

[Jon]

Thanks for the clarification - that makes complete sense.

I suppose it does not make sense to use an antifracture mat if not using self levelling compound then? Is that right?

I'll post in the find a tiler section shortly. Thanks for pointing me there.

 

[J Sid]

You could use bal single part fast flex, it's S2 and works as an uncoupling.