Tiling over existing tiles

[Rived36]

hi guys,
Im about to start a bathroom refurb next week and the customer would like me to tile over the old tiles ?
Id rather rip out but she's having none of it,
Is there anything i need to do prep wise or any special adhesives i should use?
Thanks in advance

 

[Flintstone]

Is this walls or floor? What tiles are to go on and what tiles are on there at the min

 

[Rived36]

Walls only, not sure what tiles are, id probably say ceramic and roughly 10x8"

 

[Rived36]

Ceramics going in, 600x250 brick bond

 

[Blunt Tool]

As long as old tiles are solid, good wash down and prime.

 

[Rived36]

BAL primer ?

 

[Blunt Tool]

Yes bal ok SBR primer and a powder s1 flexible adhesive standard set

 

[Rived36]

Thanks guys

 

[Flintstone]

You need to make a slurry coat. Easier to buy a ready made none porous surface primer. Personally I wouldn't tile over tile on a wall as they could have been stuck on with chewing gum over wall paper

 

[LM]

The first thing you need to establish is what sub base the original tiles are installed to.
Can the original substrate support the additional weight of another layer of tiles and adhesive?
This is the first and most important question!