Not sure how to proceed on this one.
The shower tray goes hard up against the studding. The tile-backer board is then screwed to the studding and ends just above the tiling upstand on the shower tray. So far so good. I'd planned to fit the tile-backer board on the wall and finish at the front edge of the shower tray...vertical line in red. This line is down the middle of that vertical the idea being that plasterboard would fill in gap.
The idea is plastered and painted to the left of that vertical line, tile-backer and tiles to the right (ie inside the shower area). But do I fit the tile-backer board before he plasters the lefthand side ? What about overspill of the plaster onto the tile-backer board? Tile adhesion...that sort of thing?
Or do I take the tile-backer board all the way over to the blue line and so not mess about with a thin plasterboard strip? If so then what's to stop him plastering over the tile-backer board and into the shower area (which will be tiled).
There's an even bigger puzzle I can't get my head round namely that the tile-backer board will have tiles on and so there will be the shower door assembly fitted into the tiles space but that door assembly will then leave a visible edge of the tiles going down that wall ...

Ditto at the top of the wall inside the shower itself. That room is tall and I'd rather not tile all the way to the ceiling so again there will be a lip where the tiles end and the plaster begins.
The shower tray goes hard up against the studding. The tile-backer board is then screwed to the studding and ends just above the tiling upstand on the shower tray. So far so good. I'd planned to fit the tile-backer board on the wall and finish at the front edge of the shower tray...vertical line in red. This line is down the middle of that vertical the idea being that plasterboard would fill in gap.
The idea is plastered and painted to the left of that vertical line, tile-backer and tiles to the right (ie inside the shower area). But do I fit the tile-backer board before he plasters the lefthand side ? What about overspill of the plaster onto the tile-backer board? Tile adhesion...that sort of thing?
Or do I take the tile-backer board all the way over to the blue line and so not mess about with a thin plasterboard strip? If so then what's to stop him plastering over the tile-backer board and into the shower area (which will be tiled).
There's an even bigger puzzle I can't get my head round namely that the tile-backer board will have tiles on and so there will be the shower door assembly fitted into the tiles space but that door assembly will then leave a visible edge of the tiles going down that wall ...

Ditto at the top of the wall inside the shower itself. That room is tall and I'd rather not tile all the way to the ceiling so again there will be a lip where the tiles end and the plaster begins.
