Water UFH Decoupling membrane needed? - Tile Advice

[Brody29]

I have 2 rooms to tile with ceramic tiles 15 x 60 cm tiles. There is a sand and cement screed of about 90mm thick with ufh heating pipes set within. One room is approx 5x5 metres , the other joins this room and is a hall at 1.2 x 4 metres, there is an expansion joint between the 2.
Would this require a membrane and is there anything else you can recommend i may need?
Many thanks
Mark

 

[macten]

No need for a membrane - just carry the expansion joint through the tile.

 

[J Sid]

and around room perimeter of each room

 

[Brody29]

Thanks guys , there is a 25mm celotex upstand around the slab, so if I add an expansion joint Between rooms and around perimeter, that should allow for movement all around.
Am I right in assuming I just need a watered down pva solution on the screed, and then can just spread adhesive straight on once dry? Do I need any special adhesive due to ufh?
Many thanks for advice

 

[J Sid]

no, no , no and no pva

 

[Brody29]

Hi Julian , why would you not apply pva solution ? The house is a new build and the slab is quite dusty.

 

[Flintstone]

Use acrylic primer not Pva.

 

[White Room]

Sbr is still good primer....

 

[Time's Ran Out]

Ah but is it sand/cement screed?

 

[Brody29]

Hi John , yes it is sand and cement screed.

 

[Uheat - Jake]

Seen the mention of Primer so thought I'd leave this here, very popular product...

Thermal Primer - 1 Litre (10m2) - http://www.uheat.co.uk/thermal-primer-1-litre-10m2/