Shower cubicle / uneven solid walls

[Evren]

Hi All ,

I am looking for a bit of advice on this area where i want to fit a shower tray and tile the solid walls seen in photo.
I have already removed the loose plaster and re-rendered a scratch coat on.

Now the walls are still very uneven and to completely level them i need to fill more at the bottom of walls and feather it off going upwards. Some places towards the bottom i need to fill around 2.5cm.

Now my question is ,how thick can i render (in total )using sand and cement ?
Is there a maximum thickness in each pass ?
Do i need to scratch coat OR/AND prime between every coat ?
Can i tile straight over the last coat of render (after it fully dries of course )

Can i perhaps use bonding coat or another product to bring up layers then tank it using a brush on tanking kit (mapei ) before tiling over ? Or is bonding coat a complete NO NO ?

Any other recommendations tackling this job would be much appreciated

 

[motorbiking]

Use plasterboard foam and tile backer board, with a few screws to hold.

 

[Evren]

tile backer board, with a few screws to hold.

Thank you for the reply.

I have dot and dabbed some STS board to get them all plumb and level ,once dried i will install some of those large washers as well.
Now the longer side of the wall ,i am going to batten and screw STS boards over using their directions etc.

Am i able to install a hinged shower door on this as per the positions in the attached photo ?
The door is 85cm wide including the frame and frame is around 35mm deep.
If it can be fitted on this setup , how do i go about locating the stud wall in relation to the shower tray so that the door frame sits above the tray edge ?