Flooring Tile - Floor tile what to use as a subsurface

I am planning to lay a ceramic tile in the second floor bathroom, vanity area and adjacent closet. It's all going to have to look like 'one piece' except may be a marble threshold between the vanity area and the bathroom. Subflor feels very weak even after driving some screws through the plywood into the joists on ~ 6-8 ? distance. What should I put down on plywood? Hardybacker, wonderboard, how will I make a smooth transition to the future hardwood/engineered floor in the bedroom? Or I am pretty mutch forced to install a second subfloor if I go with hardybacker like material in the bathroom, because the level of the bedroom floor shouldn't be lower then bathrooms?.

Please help,
And thanks for your suggestions in advance.

Well, if you are worried about transition from bath to bed
I would use a sheet of 1/4" Hardyback. If flex may be a problem use a small dimension floor tile to avoid cracking
(6x6 or less)
And use tile mastic, not thinset mortar, also, to avoid cracking.
If the flooring in the bedroom is a 1/2" thick 'engineered hardwood', you should be able to shim the 'hardwood' to match elevations with the bath floor.
If it is 3/8 " thick, you shold still be able to shim or float the subfloor at the bath approach to create a smooth transition.(Find out the thickness of the bedroom flooring)
However, its not a big deal to have transition piece at the threshold especially with a 1/8" difference or less.
I have been a contractor for 15 minutes, I mean years,and never heard any concern as to the bath being slightly higher than the bedroom,or vica versa(with a proper transition in place)

good luck
ryk

mik_mik,

Dont' do any of that. It's wrong. Shuffle on over to http://www.johnbridge.com/vbulletin and make a post on the "Advice" board.

You're welcome too, ryk. Better bone up on your tile setting, though.

Join John and the tile pros over at http://www.johnbridge.com. You won't find another place on the internet that has so many tile pros hanging out in one location. They not only "set" tile but they will set you straight.

Best regards.

OK, a tile site, sounds good !
I'll stand by my response, but check out John's site.
Let us know how it worked out !

good luck
ryk

Thanks to all of you guys, hmm, assuming you all are guys :)
Didn’t expect such fast response and greatly appreciate it.