Tiling over tiles - best adhesive?

[Tiredtiler]

I'm planning to re-tile area between worktop and wall cupboards in kitchen. I previously tiled it myself 24 years ago by lining the wall with chipboard screwed to a frame over the original wall. This gave a strong even surface which tiled well, concealed the wiring for the sockets etc and supported the wall cupboards (they sit on top of these boards.) The existing tiles are slim 6" square white tiles and are still completely sound and well fixed.

The chipboard and framing runs approx 6" down below the worktop (it provides a secure fixing for the base cupboards as well as support for the wall cupboards) so hacking it all out would mean removing worktop, cupboards, sink, two integrated appliances........!!

Because I've no worries about weight bearing or soundness of originals and edges are covered by run of worktop below and cupboards above I'd prefer to tile over tile rather than rip out all the chipboard and electrics.

The new tiles are small light ones - 'underground' brickwork shape/size so they would span the old grouting well.

My only concerns are preparation of the surface and correct adhesive. I emailed Unibond and they recommend simply cleaning the old surface well then using their 'Maximum Strength' adhesive but I'd be glad of advice from professionals on this. My inclination would be to source something like Bal, MAPEI or similar, although these are not so easy to come by for DIY users and they seem to have a lot to choose from.

I DO know that tiling over tiles is not best practice and I don't normally take shortcuts on jobs but in these specific circumstances the alternative would probably cause serious headaches.

SO - best adhesive? score old surface? primer???

 

[Jeff the tiler]

Give ardex technical a call they have a primer which then you can tile on to tiles. You can then use their x7 cement based adhesive. Sorry can not remember it name.
Maori also do one as well which You can get from Screwfix sorry again can not remember its name but iam sure it's on their website

 

[DHTiling]

If you have to tile over , then Mapei eco-prim grip is the primer to use.. basically it is a slurry coat type primer.

 

[jimthetiler]

skim over the tiles evenly using a flexi adhesive wait until dry then give a light rub over with an abrasive or use a scraper to take of any lumps

 

[ianflem]

Hi Tired Tiler,

I done this recently at customers request,I used Tilemaster primeplus & Tilemaster Trade Fast Flex adhesive.
Prime surface with 1 part water to 1 part Primeplus mixed with a little neat adhesive to form a brush on slurry,once dry
then carry on with Flex adhesive as normal.This was what I was advised by Tilemaster & all has worked well.

 

[PaulSmith]

Yep, Mapei Eco Prim Grip would be ok.
Broken Link Removed

Laying ceramics directly on top of old tiles.

 

[Tiredtiler]

Thanks to all who have given advice. Should have no probs now seeking out some of the products suggested and getting the job done properly.