PRIMING a screeded floor for TILES

[SavanP]

Hi all,

We have had 70 sqm of Belitex top floor screed C layed.
http://www.tarmac.com/solutions/readymix/topflow-s...

This screed has sufficiently dried and cured - it is ready for tiles.

The dilemna is now how to seal the floor, if at all, before the tiles are layed with flexible adhesive. The entire floor is underfloor heated and we are using porcelain tiles, however does the screed need a coat of PVA first?

Researching the internet, speaking to the concrete people and asking a chemical company has had differing opinions. Shall I use PVA, SBR or none before tiling?

[paulrockliffe]

The thought that it needs sealing wouldn't even cross my mind. I can't think of a single reason why it would, or how a coat of PVA is going to do anything once you've covered it in tile adhesive.

[SavanP]

The opinion of the chemical company is that nothing should be done, except for a damn good clean.

The reason behind the primer is to seal the dust that could ask as a layer to stop adhesion to the screed. However this screed is solid and doesn't seem to wear, so I am tempted by this idea.

[chippy348]

You really need to go on the advice of the adhesive that you are going to be using to stock the tiles down with.

Do you know what brand / type of adhesive you are going to use ?

[Jonesy23]

Depends on the screed but I wouldn't go for PVA, I'd got for whatever primer matches the adhesive.

From my experience the primer helps bind the top layer of the screed so no dust or whatever, made the surface much less water absorbent and in theory at least it should help limit reactions between materials.

[SavanP]

I am now torn between nothing but a clean and using a primer!

Too many differing opinions.

[Spudler]

SavanP said:

I am now torn between nothing but a clean and using a primer!

Too many differing opinions.

If in doubt, prime away!

[wolfracesonic]

SavanP said:

I am now torn between nothing but a clean and using a primer!

Too many differing opinions.

Here's another opinion: Send an Email to the technical department of your adhesive manufacture telling them what your screed is and does it need priming/which of their products they recommend. Should take 5 minutes, definitely quicker than ripping up 70sqm of de-bonded tiles.

[Neil - YVM]

wolfracesonic said:

SavanP said:

I am now torn between nothing but a clean and using a primer!

Too many differing opinions.

Here's another opinion: Send an Email to the technical department of your adhesive manufacture telling them what your screed is and does it need priming/which of their products they recommend. Should take 5 minutes, definitely quicker than ripping up 70sqm of de-bonded tiles.

Or simply read the instructions on the back of the adhesive.


Oh and never, ever PVA prior to tiling.