Transition from hardiebacker to sheetrock

I've never shimmed out my backer board like that. If i did, I'd put the same thing behind the sheetrock to make it even.

You have to shim the whole stud not just where the backer board goes.

I'm tiling up to the ceiling so I'll have backerboard all the way up the stud. My transition will be a vertical joint where the backerboard will meet the sheet rock that was installed years ago during construction.

How thick is the tub flange---????
Usually , the 1/2" backer rests on the top of the flange and does not cover it---then that void is filled with thinset as the tile is installed.

If the walls are to be waterproofed before tiling---the void would be filled with thinset before the waterproofing is applied.

AS others have said----if you furr out any part of the wall, you must furr it all--
Tile requires a flat surface or the tile edged will 'lip' badly and you will hate it.

Here's a link to the instructions for this tub:

http://www.us.kohler.com/webassets/kpna/catalog/pdf/en/1084213_2.pdf

This shows the furring strips coming down to the tile flange and then the backerboard going over the flange. This is my first tub working with a tiling flange. Is this unique to tubs with tiling flanges?

If you do as I suggested--stop the board above the flange and fill that gap with thinset--you will be fine---

Furring the wall is fine if you don't have to have the tub area board meet the drywall that is against the studs----those instructions sure weren't written by a person that actually installs these in the field.

His instructions are flawed---not addressing conditions found in real world construction.

Thanks oh'mike. I'll do as you suggested.