Wonderboard question [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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04-08-2010, 02:07 PM
I am in the process of redoing our Kitchen floor and had a question regarding the installation of wonderboard. I know I need to use thinset to attach the wonderboard to the subfloor. The previous owner of the house had vinyl tile laid on top of hardwood floors. When I removed the plywood they had the old tile laid on top of there was a layer of black felt paper from the previously removed vinyl tiles. Is it ok to apply the thinset directly to the hardwood/feltpaper or should I put a thin layer of underlayment down and thinset the wonderboard to the underlayment. Any help/suggestions would be greatly appreciated. Thanks.

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04-08-2010, 02:13 PM
No, it's not OK to install backerboard directly over sawn lumber like hardwood flooring. You must first install a layer of 1/2" plywood, then your underlayment of choice. The black paper must be removed from the hardwood before installing the new plywood.

04-08-2010, 02:24 PM
Thanks for the Advice. Just curious whats the reasoning behind removing the black felt paper?

John Bridge
04-08-2010, 05:47 PM
Hi and welcome aboard. Please give us a first name. :)

The felt might somehow cause voids between the layers. Best to remove it. When you install the new plywood screw it only to the subfloor, not to the joists.

04-11-2010, 06:22 PM
I am planning on tiling my kitchen floor over the next few weeks. I removed the old tile floor to find a layer of plywood (also removed) and found hardwood floors underneath. I am curious as to what subflooring options I have. Any input would be greatly appreciated. Thank you.

04-11-2010, 08:59 PM
Is that a hardwood finish floor over something else you have OR a plank subfloor attached to the joists?

04-11-2010, 09:02 PM
Chris, it'll help if you'll keep all your project questions on on thread so folks can see what you're working on and what's been previously asked and answered. We can give it a more generic title any time you'd like to suggest one. :)

04-12-2010, 02:00 PM
The Hardwoods are original to the house (1927) and they are over plank subfloor attached to the joists. Thanks.

04-12-2010, 02:03 PM
Chris, the easiest thing is to remove the hardwood, add at least 1/2" of plywood, then a membrane or backerboard and your tile. By taking out the old hardwood, you gain almost 3/4" of height for your new materials.