Tanking vs thick layer of adhesive

[144cas]

Hello. I’m having a Wetroom shower tiled. One side is a new wall made of Wedi boards which have been tanked. The other wall is an existing wall (mix of plasterboard and old lathe and plaster wall). Tilers have applied tile adhesive directly to that wall without tanking. On querying this with them, they have said that the wall was not true so they have used a very thick layer of adhesive in order to bring it level hence tanking was not necessary as you’d never get water ingress through such a thick layer of tile adhesive. Is this acceptable or should they have tanked it?

 

[Swwils]

It should be tanked as this is now "recommended" even in domestic shower areas under the British standard.

It also should not have been brought true with adhesive, that's literally what the wedi board is for.

 

[144cas]

Thanks Swwils. I suspected this was not to standard. But in reality, if the adhesive was thick enough on this other wall, is there any prospect of water ingress or is it possible that with sufficient thickness of adhesive, it can be considered “waterproof”

 

[Swwils]

Most tile adhesives are water resistant but not waterproof.

 

[144cas]

Understood. Would you insist they scrap the wall and retile after tanking ? Irrespective of how thick the adhesive was set? Or does their theory of “it’s thick enough to prevent water ingress” hold true at some point

Thanks again for your response .much appreciated.