Advise Required

[Channi]

Hi everyone, this seems to be a very friendly and helpful site. I'm a DIY'er that needs a bit of advise and I was wondering whether someone may be able to help me.
I'm tiling a new en-suite in my house, I have tiled (porceline) on a wooden worktop where a free standing wash basin will go. However, when the adhesive is drying, the tiles seem to move a couple om mm's here and there which looks a bit rubbish.
Should I be doing something else or am i usinf the wrong adhesive (unibond flxible adhesive).
Your help would be much appreciated.

:sad_smile:

 

[Dan]

When you say the tile move a couple of mm, do you mean they sink into the adhesive a couple of mm or they sort of slide apart a couple of mm?

Oh, and welcome to the forums

 

[Channi]

Hi Dan, thanks for replying, the tiles are pretty big (600 x 400), they seem to have dried with some raised unevenly but not horizontal movement just vertical. I don't know if I've explained that well enough.

 

[Dan]

So it could be the weight of the tiles pushing them out a little? I'm just trying to picture it and am struggling. Is it a wall or an actual flat surface (worktop type thing)?

If it's the weight of the tiles pushing them out of line a little, then you could do with using a batten perhaps to stop them moving. If they are lying flat on a work-surface type affair, and they are moving in only one direction, then I am baffled without seeing the job I think.

Got any pictures?

 

[Channi]

Hi Dan, yes the tiles are on a flat surface on a worktop, I suppose it could be the weight of the tiles but I guess then that the whole tile should sink. This appears to be one end of the tile is moving as the adhesive is drying. I was thinking that the adhesive is soaking into the wood more in certain places and drying differently thus causing one end to be ligted as the other end is drying and contracting but that's just an amateurs thought. Do I need to seal the wood with something first?
I don't have pictures here at work but I'll try to get some tomorrow.

 

[Dan]

You have to make sure that you're using the right adhesive first. Porcelain has a very low water absorbtion rate so the adhesives that stick to that generally stick to the surface of it rather than soaking into it. Therefor, the polymers used in the adhesives that make it do exactly that should be ok to stick to the surface of your worktop. If it's a sealed malemine worktop type thing you need an adhesive that will again stick to the surface of it rather than soak in it. If it's a HDF/MDF type worktop then you may need to prime it but most adhesive have priming agents in them to stop the water being extracted from the adhesive mix.

You could physically check to see what's going on. as soon as you see a tile sink a little, pull it up and see what the adhesive is doing. I'd double check that your adhesive is suitable though too.

You need a porcelain adhesive, then maybe as they are big, a 'pourable thick-bed' (PTB), then maybe even a version that's suitable to sticking to the type of wood you're sticking to.

Then from an applications point of view, you need to check you're not using too much adhesive which can cause shrinkage of the adhesive as it cures/sets, which maybe what's happening here.

Sounds like you have a flexible adhesive (covering you for the wood) but is it an adhesive designed to work with porcelain, and a large tile?