Newbie Looking For Advice on Expansion Gaps With UFH System

[Uheat - Jake]

Thank you Jake your answer is totally appreciated.

I don’t blame you for your stance on these panels, I completely agree and would never tile to them myself, of which I’m sure you know from my previous posts.

If I can push my luck a little further please, how would you deal with a change of substrate, do you use your gypsum boards as a decoupler and just span the joint?
Or are my fears of crossing from one to another warranted?
Thanks Jake.

With our Gypsum the boards would be fixed down to the timber however leaving a expansion would be fine to do if they're was any concerns by installer. Our boards don't have decoupling properties so we recommend if an installer is going to use one then put a skin of Flexible SLC over our panels before laying the decoupling membrane and then tiles.

@Nic B No problem, happy we could help. If you're worried about cracking of tiles using the EPS then you could use a screed board over the top of the panels which would offer a solid base for the tiles. However these are 20mm in thickness, which would be added to your floor height.

 

[Nic B]

@Uheat - Jake thanks again. I was reading about those and considered them, unfortunately floor height is already set and bifold doors etc installed so any additional height is obviously going to cause us a hug problem, over and above the fact that we are already massively over budget and borrowed up to our eye balls!

First proper building project I have ever done and I now understand how it spirals out of control so quickly!

 

[Nic B]

So I decided to drop a quick email to Wundafloor technical regarding the application, crossing substrates and the need for expansion gaps, below is the response I got -

Our first consideration is the transition between the concrete/floorboards section. We would hope to see it flat, stable and level.



Secondly, regardless of tile dimension the adhesive being used is highly deformable thus taking movement & expansion into account, either C2 E S2 or C2 FT S2. This has always been sufficient in the case of large format tiles over large areas and we are unaware of any further expansion gaps being necessary.



We’d advise consulting with your tiler on this matter, as they may wish to recommend further decoupling/anti-fracture strategies etc. As far as we’re concerned though, we’re quite happy to see tiles of those dimension bonded directly to the panel using a highly deformable C2 E/FT S2 adhesive.

Considering what I have read on this forum, I would be surprised if they were unaware of any issues!

Not sure if the above is useful, but thought I would share it with you all anyway.

Catch 22, don't follow their instructions and there is no arguement from my side, follow their instructions and it goes wrong and it becomes he said she said and trying to prove it was done right. Seems like I am damned if I do or damned if I dont...

Once again, thank you for all of your assistance with this.

Cheers,

Nic