Tile on Tile

[EXRM1802]

I have recently looked at a job in a care home that requires me to tile on existing tiles (money is an issue) the walls are in good order.
I`m new to this scenario - what do i need to know?
What adhesive would you reccomend?
Should this effect my pricing at all?

Thanks again

[Fekin]

The existing tiles must be soundly bonded to the walls. Obviously, no matter how well fixed the new tiles are, if the old tiles de-bond from the wall and fall off, then so will the new ones.
Tap old tiles to see if they sound hollow, as this will tell you if the tile is or is not fully bonded to the wall.
If the old tiles and new tiles are fairly average and not large heavy formats it shouldn't be a problem.
Remember plasterboards\plaster have a recommended weight limit per sqm, plasterboards around 33kg per sm, plaster is around 20kg sqm if I remember correctly.

Remember to score the old tiles first to give the adhesive a good grip.

Bal Grip might be a good choice to eliminate slipping, but I'd dare say standard Bluestar would suffice, unless if it's in a wetroom, then maybe go for White or green star.

If the existing tiles are nice and flat then pricing should be the same as standard tiling onto fresh good plaster really.

Oh and if the new tiles are roughly the same size as the old tiles, then it might be worth trying to setout a little different to the old tiles, "depending on how your cuts will fall though" so each of your new tiles covers 2 of the old tiles "staggerd" if you know what I mean.
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And remember to clean and de-grease the existing tiles completely.
Sugar soap is a good cleaner, then let the walls dry completly.

[Dave]

white star or spf adhesive would be my option... when tiling over existing tiles... green star not suitable for bathrooms ....good luck...

[clarke]

White star every time! Stagger the grout joints too if poss.
I would maybe try chipping one tile off too see if theyre stuck well, if it falls of without much effort then take em all off. If the weight is too much (which it could be) then you could be taking a gamble.
If theyre stuck good and proper then BAL white star and superflex wall grout would be my choice any day.

If you're using tubbed adhesive you need to wait about 3 days before grouting.

[groucho]

I used Ardex D20 recently over tiles and it was very good. No slip at all. But you do have to leave them a lot longer to dry out before grouting