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Install & Replace

Backer Board directly on 2x6" tongue and groove subfloor

I am replacing the carpeting in my hall with 12” ceramic tiles. It is a standard carpet with pad on top of 5/8” particle board. This is all setting on a 2”x6” tongue and groove subfloor. I am hoping to use Custom Building Products Wonder Board 1/2 in. Backer Board and the ¼” tiles right on the subfloor. This gets the height close to matching up with the hard wood flooring in my entry way. Questions are:

Is the ½” backer board and 1/4” tile strong enough together with the subfloor? Or do I really need an extra layer between the backer and subfloor?

Do I still need to use Thinset/mortar under the Backer Board?

What is the smallest width that the backer board can be? (My hall is 3’5” wide and I am thinking that it would not be a good idea to only have a 5” wide piece but to instead use 2 wider sizes)

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Posted 2011-09-19T22:26:08+0000  by Macaw Macaw



My name is Tom, known here as HD116, and allow me to welcome you to our community. Thank you for your question, it is one that gets posed to flooring associates in my home store often.


1) The backer board must go over a subfloor base, and the although the 2" x 6" tongue and groove along with the backerboard might be sufficient and structurally sound enough for the addition of tile, I would add a layer of plywood. My question would be how much "give" does the 2" x 6" subfloor have when the backerboard is laded over it and you are standing between the joists? If it gives at all, you should add a layer of plywood that is thick enough to not allow any "give" in the floor. Failure to do so will likely result in backerboard, tiles and grout cracking or breaking as they are not designed to "give" at all.


2) Thinset or another appropriate adhesive designed for tile would be required to adhere the tile to the backer board.


3) Considering that a subfloor is required and would provide the needed support, you can use a 5" piece or you could cut a 4 foot wide piece to the 3"5" required.


There are a few other posts here from a few of our Experts and community members that may be of interest. They follow here -


Also Home Depot has a good overview which can be found here.


Finally, if you end up with a floor that is slightly higher than the hardwood in the adjacent room, have no concerns. We have transition strips in a variety of finishes that are designed specifically to address that issue.


Hope that helps.



Posted 2011-09-21T16:29:41+0000  by HD116
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