Advice On Rectifying A Pre Tiled Wall That Takes A Dive!!

[Nedson]

Hi fellas,im looking for some advice please. I'm a reasonably competent diy'er completed numerous tiling projects over the years, last one was my main bathroom stripped back to stud and used wedi board and tape etc.
Currently doing en suite and I've decided to go down the tanking route, showers all in recessed behind wall and tray is all bedded in. I've just had a rough set out to calculate tiles (600x300) with a rod and I've noticed the adjacent wall that dies into the shower wall takes a dive of about 15mm over the last 700mm so it's quite pronounced, it's fine near the ceiling and fine at the bottom where the tray is butted up,it seems to be an area around waist height, obviously a bowed stud.
As the tray is all in I really don't want to start pulling plasterboard off and relining.
Would it be acceptable to sort this by skimming with flexible tile adhesive to even out the 15mm, let it dry then tile on top of this, bearing in mind it's within the wet shower area. If it was else where I probably would have just walloped loads of adhesive on the back of the tile to make up the difference but I'm thinking voids behind the tile in the wet area is asking for trouble.
If this is acceptable would it be best to tank the area before or after skimming?
Thanks in advance.

 

[White Room]

Any pictures....

 

[One Day]

The correct way - and ultimately the easiest - is to take off the board with the offending stud/s and straighten them out. Replace the board, tank it and tile. Any other way around this is going to be tough and in my opinion - a bodge!

 

[Nedson]

 

[One Day]

Oh! I thought it was bellied out. Yes, build that out with some adhesive. Tank after. Be mindful of weight limits on skim plaster though. You'll be adding to the limit, especially if you hang porcelain or stone. And sbr the plaster first.

 

[Nedson]

That's great, thanks for the reply.