Proper subfloor when you have hardwod over concrete!!

jamshedNovember 28, 2011

I am replacing the kitchen floor in my daughter's 1930's DC coop townhouse. The kitchen has hardwood floors which are sturdy, but the finish is ruined and water damaged. She wants to put down tile.

Now I know that Hardiback over hardwood is a no-no. But here's what we found. We pulled up one of the hardwood boards and underneath it is a concrete floor. (She is on the second floor.) The hardwood is not laying directly on the concrete which is quite rough. There are 1x2 (?) slats that appear to be fixed to the concrete, and the hardwood is nailed down perpendicular to the slats. The floor is perfectly level, but as I said earlier, the oak hardwood has shrunk, specially near the sink and dishwasher.

QUESTION: What should we do. My gut tells me we should rip out the hardwood and put down 3/4" ext ply over the slats, then thinset down 1/4" Hardiboard and finally the tiles.

Does this sound like a good idea? I don't want to cut corners, but I also don't want to do anything unnecessary.

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Some people go to great lengths to have concrete floors. I know your plans are to lay down wood, but what about just giving the concrete a nice polish and stain?
Best of luck with your project, I hope your daughter appreciates your efforts.

    Bookmark   November 28, 2011 at 2:08PM
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Skip the plywood + cement board, and just apply Ditra to the concrete floor as a tile substrate. Installing wood just adds a component to the floor that can move and cause cracking.

Here is a link that might be useful: Ditra installation info (see pg 10)

    Bookmark   November 28, 2011 at 2:21PM
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"Some people go to great lengths to have concrete floors. "

And many of them regret it as they age and the stiffness of the floor takes its toll on knees, hips, and backs.

Or you add cushioned mats to stand on creating one more thing to clean.

    Bookmark   November 29, 2011 at 10:26AM
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The concrete floor is VERY rough and would not make a suitable substrate, even for Ditra. I'm thinking of just doing the ply over the slats and Hardibacker and tile.

The good thing is that the slats aren't going to flex at all.

    Bookmark   November 29, 2011 at 10:06PM
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