Remove Plywood Subfloor?

cpbraun

My builder installed carpet in the upstairs bathrooms. I want to put in ceramic tile. should/can I remove the plywood floor and install backerboard directly on the joists, or must I live with the buildup height and put the backerboard on the existing plywood?

AtlanticWBConst.

Carpet in the upstairs bathroom?? Yuck.

Absolutely leave the plywood down...you need that for a solid subfloor to install your tile on. You want as little flex as possible in the flooring to limit tile cracking and grout coming out.
Try using 1/4" Cement board and just install a transition threshold to adjust for the diference in height.

__________________
- Build Well -

Bonus

You have to leave the plywood, in fact you should probably add more. What thickness is the plywood? How large (depth: ie two inches X how much?) are the joists? Can you figure out the span of the joists? Backerboard does not add strength to the floor, it merely seperates the tile from the possibility of movement in the plywood.

Blaze25

Assuming your floor is sufficiently strong enough as per Bonus's questions, I would use Schluter Ditra. It will not significantly raise the hight of your floor and will provide a waterproof membrane and uncoupling layer that protects against tile cracking and delaminating.

http://www.schluter.com/