Advice on tiling onto "overlay" underfloor heating - TilersForums.com

[Old Mod]

There are other overlay systems that are much safer to use Jon, Polypipe being one, or other similar types. These are installed in to inert gypsum or cement based boards and are far more suited to your application.
You may also consider Bekotec therm from schluter, it’s a very low profile ufh system fitted in just 35mm of screed (I think it’s 35mm) which can be run hot or cold. I must admit I don’t know off top of my head if it’s suitable with your heat source. But knowing schluter, I’d be surprised if it wasn’t.

 

[Jonner]

Hi Marc
Many thanks for these comments.
We are actually now considering the attached as our favorite option, following further discussion with our heat pump installer.
Any experience or comments?
Cheers Jon

 

[Jonner]

It looks very similar to the Schluter system too )

 

[Old Mod]

The schluter system has a sand and cement screed applied to the top.
Are using the plastic or gypsum boards Jon?

 

[Flintstone]

Schluter system looks very impressive. You can use it on top of various sub floors and it’s only 25mm total build up

 

[Old Mod]

Schluter system looks very impressive. You can use it on top of various sub floors and it’s only 25mm total build up

Oh 25 is it Andy, thought it was 35.

I don’t think I’m grasping this system, does it use both the plastic and gypsum boards, or is it either or?

 

[Jonner]

From the download i send of the Low Pro 10 it looks like it uses gypsum (or similar) boards for the straight sections and includes the curve detail for one of the ends and then you use the plastic castilation panels to make the other curve end.

Not sure if we need to put additional insulation down on the floor first?

 

[Old Mod]

Oh ok, a little odd, but ok.
So first thing to note, gypsum boards.
Gypsum and cement don’t mix well. Make sure the gypsum boards are well primed, not with pva! But an acrylic or an sbr based primer. Minimum 2 coats.
Pressurise system as suggested and leave at around 5-6 bar if possible. Latex over pipes regardless of what instructions say. It will eliminate voids beneath your tiles and afford a better transfer of heat to your tiles. You can use an anti fracture mat as opposed to a full decoupler. Few differences but in essence an anti fracture mat is only 1mm thick as opposed to 4-5 with a decoupler. Let any decoupler or anti fracture mat cure overnight. Do not tile it straight away as suggested. Then tile.
Do not use suggested adhesive unless a professional tiler is doing the job. You WILL throw away more than you use if you are doing the Tiling. It’s one of the most difficult adhesives out there

 

[Jonner]

Thanks again Marc
on page 5 they mention "schnellgrund" primer to seal the gypsum
I will look onto acrylic or sbr primers as i will be doing this bit once pipe is laid

As i am doing the tiling was thinking of going for de-coupler (belt and braces). Did not realise that the decouple had to be "bonded". I guess with a felxible tile adhesive?
Please could you suggest an adhesive that i might have some success with, as yes i am planning on tiling
Cheers Jon

 

[Old Mod]

What is your tile choice Jon, I apologise if it’s been mentioned already.