[4just1don]

In my bathroom project I have 3/4 pine subfloor(NON- tongue and groove) there are some spaces in it..

menards sign says you need at least 1 and 1/8" of subfloor to support ceramic tile. 3/4" subfloor and 1/2 inch durorock cement board would do that,,,right??

There is oak floor of old and varied quality,from missing to rotted to replaced with chunks of plywood years ago. IF I left old floor in there I would be a bit over 3/4 " too high with finished floor.(and would take a TON of work to repacing missing areas)

Other reason I wanted it out is screws would be hard pressed in 3/4 inch oak,,,without predrilling each hole.

so is pine subfloor plus cement board enough? Or put down 1/2" plywood first on to subfloor,then 1/2 cement board then tile?? THAT would make me about 1/2" too high to match proposed level of refinished old harwood now under carpet,,,which I can transition I spect!!

thanks -d-

[DangerMouse]

sounds ok to me don, but how about 1/4" ply? then you'd only have 1/4" to deal with. you are right about the oak, it'd be a real pita to screw through.

DM

[RippySkippy]

What is the joist material and what's the span? Gotta know these two things before proceeding.

The cement board is NON STRUCTURAL...and adds nothing to the overall strength of the floor all it adds is height. Typically 1/4" is all that's needed for flooring, assuming your sub-floor is adequate. Buz over to John Bridge and plug your measurements into the Deflectolator...plug in your values and it'll give you a point to start from and you can make decisions from there.

[Bud Cline]

Cement board over slats is never recommended.
The use of 1/4" plywood is never recommended, 3/8" is the minimum.

[26yrsinflooring]

Install the 3/4 plywood and use Ditra. This will keep your hieght down,your time down and give you a top quality substrate for your tile.

[4just1don]

the span is LESS than 10 feet with 2 X 8's on 16" centers,,thats the BEST part of the house,,,they didnt put center supports uder the center beam(They are going in now) and no sill plate,,,BUT its been this way for 50 years or so,,I guess it works,,,going to rework that also in this general rehab. Thanks for the replies,

another stupid question but I have never used it before,,,whats the "ditra" product?? Is that like a rubber membrane or something??

[26yrsinflooring]

View it here: http://www.schluter.com/5793.aspx

[4just1don]

Thank for the ditra link,,looks like GOOD stuff.

Does one use GREEN treated plywood in this high moisture area of a bathroom?? And if so,what kind of fasteners so they dont rot off?

[26yrsinflooring]

Galvanized deck screws.

I could tell you where to find the best price in nation on the Ditra but the locals will call it advertising.