Schluter and anhydrate screeds .

[Dumbo]

Does anybody know the answer to this.
Schluter claim with ditra matting you can tile an anhydrate screed up to 2% moisture by volume . Question is does anybody know what that is as an rh figure .
Thanks in advance for any help and wee wee taking

 

[Qwerty]

Good question...... @Ajax123 ?

 

[One Day]

I think (from memory) that's 80% rh.



(might be 85% though!)

 

[Dumbo]

Good question...... @Ajax123 ?

It's one that schluter couldn't answer

 

[hmtiling]

With what adhesive? Anhyfix is good from 85%rh anyway. Most cement based adhesive is 75%rh maximum. Not sure what is being claimed here or am I missing something (very possible)

 

[Ajax123]

Does anybody know the answer to this.
Schluter claim with ditra matting you can tile an anhydrate screed up to 2% moisture by volume . Question is does anybody know what that is as an rh figure .
Thanks in advance for any help and wee wee taking

1.5% moisture by weight is 92% rh. The only system I know of guaranteed to work at higher than this is Norcross progyp base which is ok at 95%. GYPSOL screeds will achieve this after about 7days.

 

[Old Mod]

1.5% moisture by weight is 92% rh. The only system I know of guaranteed to work at higher than this is Norcross progyp base which is ok at 95%. GYPSOL screeds will achieve this after about 7days.

Ooow oooow is that a secret formula Alan?

 

[Dumbo]

Gypsum based screeds
According to the applicable standards, the residual moisture of gypsum based screeds should not exceed 0.5% (percentage by volume) prior to the installation of tiles. With the application of Schlüter®-DITRA 25, tile coverings can be installed as soon as the residual moisture is below 2.0% (percentage by volume).
This copy and paste from schluter

 

[Ajax123]

Gypsum based screeds
According to the applicable standards, the residual moisture of gypsum based screeds should not exceed 0.5% (percentage by volume) prior to the installation of tiles. With the application of Schlüter®-DITRA 25, tile coverings can be installed as soon as the residual moisture is below 2.0% (percentage by volume).
This copy and paste from schluter

But what is their recommendation of what to stick it down with at 2%?... I suspect they have not got one as they seem to have a relationship with Bal and Ardex who have nothing that I am aware of to stick to anhydrite at such high levels of moisture.

I am really only interested in what happens to the screed. We have tested it up to 1.5% moisture or 92% RH with moisture control systems and Norcross have tested up to 95% RH on their system.

Ooow oooow is that a secret formula Alan?

If I told you the formula I would have to shoot you... lol... no its simply based on testing in controlled conditions using different methods of measurement back to back....

 

[Old Mod]

If I told you the formula I would have to shoot you... lol... no its simply based on testing in controlled conditions using different methods of measurement back to back....

Haha fair enough Alan,
Funnily enough, I’ve just emailed you.