You may wish to consider .5" plywood and ditra, this stuff...
http://www.schluter.com/6_1_ditra.aspx




"Mikepier" wrote in message
ps.com...
I can only go 3/4" high due to height problem matching existing floor.
So whats better?
A) 3/4" plywood,
B) 1/2" ply plus 1/4" backer
C) 1/4" ply plus 1/2" backer

Forgot to mention I am still keeping my 3/4" subfloor.