Ceramic tiles on a new concrete floor

[Alcazar]

I'm almost at the stage where I'll need to think about tiling the floors in the extension.

It has a concrete floor, which is a little dusty.

Do I need to seal it with anything before tiling?

And is it OK to tile straight onto the top of the cement surface (after sealing?), or will it need levelling compound first?

TIA, Alcazar

[AllezAllezAllez]

I've tiled straight onto bare concrete on two floors and had no problem with damp or fracturing.  On one of the floors, which is sufficiently above ground level I painted on a blue liquid sealing agent made by Lanko because I suspected that there was no membrane laid beneath the concrete.  The same product is used to seal plasterboard in showers etc.

The other floor which did have a membrane, I just laid the tiles direct after giving it good sweeping and vacuum clean.

Some people will tell you that this is wrong as concrete is liable to small movement with temperature change which causes the ceramic tiles to break. Hence a 6 cm screed layer will provide the necessary flexibility to absorb any potential movement thus preserving your tiles.

Levelling compoung is useful but quite expensive.  You can lay it in patches where your floor level is undulating, but I would not cover he whole floor if your ruler only shows a few imperfections.

My neighbour and other people in our village have laid straight onto concrete for years and the only cracks in the tiles on their floors are where the large copper frying pan gets dropped 

 

 

[Alcazar]

Thanks for that.

No problems with them not sticking properly either then?

Alcazar

[vrooje<BR>Cheers,<br>-Brooke<BR><br><B><A TARGET=blank HREF="http:www.experienceburgundy.com">http:www.experienceburgundy.com<A><B>]

Alcazar,

We just laid tile in our kitchen, right on the concrete. We only put membrane down in two places where there were cracks, so that as the cracks settle they won't shift the tile. We had no problems with the tiles sticking.

We were going to tile our study/office as well, but the cracks there were large and numerous enough that our tile layer didn't feel comfortable risking it.

One piece of advice: if your floor is very slightly off-level, it's not a big problem. If you lay out the tiles and they wobble at all, consider using a leveller of some kind... one portion of our floor was noticeably off-level and it was a bit of a nightmare. It looks fine now but to our eyes there are inconsistencies here and there. Of course, we were using very large tiles, so this exacerbated the problem...