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J

Jonner

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Hi, my name is Jon

I have already had a look around the forum and it has already been really useful regarding tile onto an overlay underfloor heating system, but it has raised a few questions!

I will shortly be starting a floor tilling job onto an overlay (water based) underfloor heating system. The underfloor system is in conjunction with an Air Source Heat Pump (flow temperatures about 35deg C).

The PE-RT (polyethylene pipes are laid into a foil insulated polystyrene foam). From what I have read on the forum I am then planning to do the following:

  • Bond on a “backer board” using a flexible https://www.tilersforums.com/forums/tile-adhesive/ – I was planning on using 12mm thick minimum. Is thicker board better? Should the backer board be screwed down?)
  • Lay down a de-coupling membrane
  • Bond either stone or ceramic tiles to the backer board

Please could you advise if the steps I am proposing are correct and any materials you would recommend.

Any help/advice really appreciated, thank you.

Best Wishes

Jon
 
OP
F

Flintstone

What do you propose to use to bond the backer board to the foil? It’s come to light recently thay something in the aluminium breaks down cement based adhesives.
 
OP
J

Jonner

Hi ACT
Firstly many thanks for getting back to me. Thank you for highlighting this potential problem with the https://www.tilersforums.com/forums/tile-adhesive/ and the aluminium.
I am open to suggestions on what materials to use for this job so if you have any recommendations for https://www.tilersforums.com/forums/tile-adhesive/ that would be greatly appreciated.
Or could the aluminium foil simply be removed before bonding the backer board?
best wishes Jon
 
OP
F

Flintstone

Morning jon.
Personally I have never tiled onto one of these systems, I have managed to avoid so far and turned down a couple. Some on here will advise you better than I can.
 
OP
S

Spare Tool

Far as I'm aware its all in the priming and putting a barrier between the aluminum and Portland cement, Imo a good coat of eco prime and grip followed by 10mm of a flexible self leveler would be the way to prep this type of ufh
 
OP
J

Jonner

Hi Andy
Many thanks for your comments, really greatly appreciated.
When you mention priming the foam backed aluminium would something like Mapei Eco Prim Grip be the right thing?
You then mention a flexible leveling compound, would something like BAL - level max be the right things?
Would you propose the self leveling compound instead of the backer board? Or would the backer board be laid and bonded onto the self leveling compound?
Sorry for the additional questions.
Best Wishes
Jon
 
OP
S

Spare Tool

Personally id stick with the same manufacturer for primer and self leveler, I only use ultra and Tile Master so can't comment on the BAL, but both TM and Ultra make a prime and grip primer and slc suitable..
And yes the slc is instead of the cement boards, will disperse the heat better
 
Last edited by a moderator:
OP
O

Old Mod

Ok so this type of retro fit ufh installation is the most difficult to deal with from a tilers point of view.
Aluminium spreader plates and tile https://www.tilersforums.com/forums/tile-adhesive/ are not a match made in heaven, in fact there is a chemical reaction that takes place.
A couple of things first, what substrate are you laying your polystyrene boards to?
Is it a floating floor? (Chipboard laid on insulation with no fixings)
I cannot see in the literature a list of suitable finished floor coverings.
What I can see, is only images showing the finished floor as timber planks on top.
Is this suitable for tile, have you inquired?
I can not find any fitting instructions either, only a one day acquaint class.
If you have any links to any of the questions it'd be really helpful.
Thanks.
 
OP
J

Jonner

Hi 3 Fall
Firstly thank you for your time & help with this
The floor is a solid concrete floor, which has been "tanked" with a plastic liner (sheet) CDM membrane (manufactured by Oldroyd). This CDM liner is lapped up onto the walls by about 6inch. The polystyrene boards will be laid onto this.
I have mailed Hetta to understand what floor coverings can be used but from very initial dialogue with them understand "any flooring" can be used! If i get any answers from them i will let you know.
Only other piece of info is that this is being used with an Air source heat pump so flow temperatures will be about 35 deg C
Best Wishes
Jon
 
OP
O

Old Mod

Ok Jon, kool.
I would insist on a method statement from them in writing.
This is critical I'm afraid.
There's been a lot of social media chatter in the race forums about this and similar products.
Myself and a colleague of mine, investigated a massive failure earlier this year, which happened to be on this type of UFH.
Here is the thread I wrote, my colleague published elsewhere.

https://www.tilersforums.com/threads/retro-fit-ufh-hydrogen-gas-causes-floor-failure.83724/

You will see the importance of obtaining a method statement very quickly.
There have been developments by the company features in the thread, to eliviate this problem, but we'll wait and see what 'hettasystems' have to say first.
Good luck.
 

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