Tiles not sticking

[pundabuyer]

Guys, I need help!

I have a kitchen/utility that I am tiling (floor) I have ceramic tiles and have used tile cement.

I tiled the kitchen over the pre existing tiled floor which worked perfectly they were the ancient flat tiles when the house was built decades ago an they were not going anywhere!

However, the utility has been concreted about 3 to 4 months ago and has been left to dry out, which it had.

On tiling this yesterday, it seemed to be fine - same cement and ceramic tiles but on closer inspection, after the tile had been down a few minutes on one certain patch of concrete, there was a lot of moisture coming up and the tiles have not stuck, it's as if the cement has caused a reaction and made the concrete sweat?

What do you guys think is happening? Should I seal it with pva?

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[Richard C]

What is the new floor screed made of, conventional sand/cement or is it an anhydrite screed? What make & type of tile adhesive are you using?

DO NOT use PVA under any circumstances.

 

[pundabuyer]

Its is standard sand and cement concrete so pretty simple. The tile cement is rapid set unibond tile cement.

The cement on the tiles has gone 'sandy' and damp as if the excess water stopped the chemical reaction, would it be best to use a - non cement adhesive? what do you think, why the strong warning about PVA - remember i have no idea!!

Thanks for your help

 

[Richard C]

The tile cement is rapid set unibond tile cement.

Throw that stuff into the nearest skip & go buy yourself a quality trade tile adhesive & grout; BAL, Webber, Ardex, Granfix, Mapei, (but not the stuff in BNQ) etc. Use a powder cement adhesive, tub (ready) mix is not suitable for floors. Are you sure the tiles are ceramic & not porcelain? What size are the tiles? Did you add too much water to the addy?

Standard PVA is water soluble & will re-emulsify if any moisture gets to; it is not a suitable primer for use on a tile base, it will affect tile adhesion & if used in a “wet” area or subjected to water could result in tile failure. If you need to prime, only do so if recommended by the adhesive manufacturer & use an acrylic/SBR primer.

Naughty, naughty for tiling over those tiles , I'm surprised you got away with it using that stuff . Tiles also need correct preparation, depending if they are glazed or unglazed; lets hope they stay down there!

 

[freddiemercurystwin]

i have no idea!!

Says it all RC! Why people embark on these projects before doing a bit or research is beyond me!

 

[pundabuyer]

Thanks,

The tiles are definately Ceramic and they set fine on the old floor and on the rest of the concrete.

So all you are suggesting is to switch tile cements? maybe i did add too much water if i remember correctly it was wet but not too sloppy! perhaps ill attempt again with less waetr! thanks for the swerve on PVA! life saver!

Come to think of it one of the tiles that was on the old tile floor came up too and that couldnt have been anything to do with the concrete! i think i may have used too much H20! and the tiles that did stay down fine were layed with a new batch of cement! oops!

Its amazing how different circumstances can cause a head ache! thanks again