Mapei with UHeat Ecoboard Queries - Tile Advice

[Spiralsmile]

I have ordered Mapei Primer G to prime existing screed, Keraquick to bond eco boards to floor.

Now do I need to prime ecoboards with more Primer G or use SBR? I will the lay UFh cables and pour over some Mapei renovation screed to cover them.

Prime screed with primer G or SBR??

use keraquick to lay slate on...

Am i doing this right?! ( my bank holiday is already ruined!!!)

 

[One Day]

Don't prime them. They're uncoated.
Good luck screeding those!
Imagine a thin layer of levelling compound dried on a sponge?
That's what you're going to end up with.
I suggest you try not to walk or kneel on the floor as you tile.
Might be a good idea to get a decent sized piece of ply to kneel on as you work?

 

[Spiralsmile]

Impish,

As I understand these are closed cell boards which have a very low permability?

Thus they should be no worse than primed concrete for instance?

 

[One Day]

But they are very compressible - a thin layer of slc could quite easily break on compression and leave you with lots of small loose fragments and dust.
I've used them before. Once - and never again!
the job went off ok though ;-)

 

[Spiralsmile]

Ah I understand your reference to a sponge now,

They are however supposed to have a compressive strength of 300kPa which twice that of some celotex products designed especially for UFH
http://www.siginsulation.co.uk/Literature/FF4000 Product Datasheet.pdf

I wonderng if Uheat or others might have some opinions?

 

[One Day]

300kPa is roughly 42psi.
Sorry, I just can't see it.

 

[Spiralsmile]

Uheat would want to be pretty careful so if they are quoting a Britishand European standard for their compressive strength!

 

[SJPurdy]

The celotex product is not equivalent it is (as I understand it) not designed to be tiled directly, but is intended for insulation underneath a heated screed. I am guessing from the question that the uheat stuff is.