KS7J wrote:

Hi All,

Bathroom project coming up. Part of it is to replace a wood parquet
floor with ceramic tile. Parquet is 3/8" thick over 1/2 or 5/8"
particle board over 2x8 T&G subflooring (nominally 1-5/8" thick). I'm
concerned about achieving the same level on the new floor.

Can I remove the particle underlayment and screw concrete backer board
(Durock aka Hardi-backer, etc.) directly to the T&G subfloor? My
instinct says it is stiff enough without additional plywood
underlayment. If I have to put a plywood base on top of the T&G I have
no hope of getting the tile floor to the same level as the current
floor.

TIA,

Casey

Read this: http://www.ttmac.com/deflection_limitations.htm

And forget the screws on the underlayment. You can apply the
underlayment over the T&G using tile mastic and 1-1/4" roofing nails.