What adhesive and spacers?

[crisco 78]

hi guys
can anyone advise me on type of adhesive
ive got liquid pumped screed + wet UFH, i will be laying 1200*600 porcelain which is about 135m2:mad2:
i was thinking KERAFLEX MAXI , floor primed with PRIMER G(2 coats?)
and 2mm spacers?????
any suggestions
cheers
chris

 

[White Room]

Which liquid pumped screed was it.......this is probably one for Ajax.

 

[mattle40]

Fingers crossed its not a gypsum one eh

 

[DHTiling]

You really need to source the screed type and length of time it's been down first.

 

[crisco 78]

HI
what if it is gypsum one?
its been laid over a year ago, some small cracks appeared as well
am i still on the right way or not
cheers

 

[crisco 78]

what was this mapei tape for cracks
mape....???

 

[mattle40]

Anhydrite screeds are gypsum, and are notoriously problematic, if it is identified as Anhydrite and thoroughly dry then there is no problem really but I know of a few failures due to improper prep or the fitter not knowing it was Anhydrite.
(although its not as bad these days as I think a lot more fitters are aware)
As soon as I hear "pumped" I think Anhydrite

They develop a layer of latents on the top as they dry,
This needs to come off before tiling, then primed thoroughly as gypsum and cement don't mix well!

Just something to think on ;-)

 

[Dontiler]

hello
is it's gypsum based screed I would sand of laitance in the first place before applying primer, with primer you are using I would be better of using gypsum based adhesive, as cement based adhesive reacts with gypsum screed, if you still planing to use cement base adhesive then would recommend to use epoxy based primer, also would increase tile spacers, minimum 3 mm, if screed have some small cracks would definitely recommend of using decoupling membrane, also in big are as yours would make few expansion joints, movement joints should be used to divide the tiled area into fewer areas of no more than 40 sq/metres
good luck with your project

 

[crisco 78]

so what brand would you recommend then
does mapei do them gypsum based as i had 40 bags of keraflex maxi s1 delivered today
is that still alright

 

[Dontiler]

If you bought adhesive already, then just buy Ditra matting, keraflex maxi will be fine for you application, it's just really long drying adhesive thats all
good luck

 

[crisco 78]

fingers crossed
cheers guys

 

[Finianlucian]

Hi Chris. If you're still on the forum, I'd be interested to know how you got on? I'm about do an almost identical job to the one you described above. This post was from 2012 so it would be great to know whether you used Ditra or not and if you had any problems since.