Travertine angled/mis-shaped wall

[Printisdead]

I've recently purchased honed and filled travertine 400mm x 300mm x 10mm tiles. The main isssue is the walls around my window are not plumb and the window recess is not a true 90 degrees to main wall.
I'm not a tiler but a bench joiner with an eye for detail. Its very important, especially in natural stone. (I'm taking the time to polish seen edges not using trim, looks awful!!!). So as you can imagine I want 90 degree corners around the window, no tiles kicking in or out.
The main problem is that in certain areas I will have to bring the tile off the wall (to a max of about 12mm). I thought about screw and plugging plywood shimes/packers on to the existing plastered wall, apply adhesive on top and then setting the tile directly to this. This would allow me to adjust the shimes and tiles accordingly.
Would this work as a good soultion? Any tips or advice would be very much appriciated

 

[Richardk]

I would line the reveals with 6mm Hardie or similar using rapid set and a few screws to get them plumb.

 

[Gazzer]

Why not prepare the walls correctly ?

 

[merlecollins]

Like Neale says, you really must get the prep right. I wold, if necessary strip off the existing linings to the reveals, soffit and sill and start again Get some WP Plasterboard or Hardie Tile backerboard and set them correctly sing a bagged rapid setting tile adhesive.
It would help if you could get some pics up showing how much they are out of level and plumb

 

[Bolter]

I've recently purchased honed and filled travertine 400mm x 300mm x 10mm tiles. The main isssue is the walls around my window are not plumb and the window recess is not a true 90 degrees to main wall.
I'm not a tiler but a bench joiner with an eye for detail. Its very important, especially in natural stone. (I'm taking the time to polish seen edges not using trim, looks awful!!!). So as you can imagine I want 90 degree corners around the window, no tiles kicking in or out.
The main problem is that in certain areas I will have to bring the tile off the wall (to a max of about 12mm). I thought about screw and plugging plywood shimes/packers on to the existing plastered wall, apply adhesive on top and then setting the tile directly to this. This would allow me to adjust the shimes and tiles accordingly.
Would this work as a good soultion? Any tips or advice would be very much appriciated

Ply is flexible, and tiles are not. Ply can absorb water and rot. This is not the best substrate to use Im afraid. Like others have said, cement board/tile backer board is much better for taking tiles, and you can be sure to get the walls flat and true if you take your time to get it right. You should aim to prep your walls so that a 6mm notched trowel is all thats needed, BUT you have the option to go for an 8mm if you so desire.

Flatter the walls, the better the tiling will look and the easier it will be.

 

[Polishtradesman]

Ply is flexible, and tiles are not. Ply can absorb water and rot. This is not the best substrate to use Im afraid. Like others have said, cement board/tile backer board is much better for taking tiles, and you can be sure to get the walls flat and true if you take your time to get it right. You should aim to prep your walls so that a 6mm notched trowel is all thats needed, BUT you have the option to go for an 8mm if you so desire.

Flatter the walls, the better the tiling will look and the easier it will be.

And less tile adhesive with is usually more expensive than other matirials.

 

[The Legend; Phil Hobson RIP]

I agree you can't beat a blank canvas, I would start from scratch.