Tiling over oak flooring [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Jersey Rick
07-20-2005, 05:34 PM
First of all thanks for all the advice! I've been renovating an old factory for a long time and I've done quite a bit of tiling over painted cement floors (removing the paint with a hammer drill and chipper bit or worse a diamond grinding wheel) with your help. However I now find myself installing a bathroom on the second floor over wood joists. I used the deflectometer to determine the following:

For joists that are Unknown wood, but in good condition, 12 inches tall, 3 inches wide, 12 inches on center, and 18 feet long between supports, the deflection calculated is 0.273 inches.

This translates to a deflection of L / 792.

This was a relief. I have a new oak floor in this room which I divided for the bath. So I was thinking of putting Ditra over the oak and tiling or 3/8 plywood over the oak, thinset the Ditra to the ply and tiling. Would this be a reasonable alternative to removing the oak (6 inch 3/4 wide plank over 3/4 plywood) given the above deflection number. My thinking is that the Ditra would waterproof the floor and absorb the motions of the oak. Thanks!


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07-20-2005, 05:39 PM
Hi Rick, welcome. You don't want to tile over ANY hardwood. This question is brought up quite abit. Hardwood is unstable. You want to remove it then see what the subfloor is to see what you need to add to it.

Jersey Rick
07-20-2005, 06:35 PM
Wow! That was quick! Thanks Mike. Well I'll tear out that oak then. I know that I have 3/4 ply under the oak since I checked today, so I presume another layer of 3/4 plywood and ditra or backerboard thinset to the new substrate should do the trick? This is my first bathroom so I'm double checking every move before I start. Better safe than sorry!

07-20-2005, 06:41 PM
Welcome, Rick. :)

Hellofa joist system! :D

What Mike said about removing the hardwood. You really gotta do that. But with the joist width and spacing you have, the 3/4 plywood subflooring, if still in good condition after removing the hardwood, would be sufficient under the Ditra or a CBU, whichever you choose. If you need to add height, more plywood is never a negative on a subfloor.

If you need a lot of height, you might consider mud instead.

My opinion; worth price charged.

07-20-2005, 06:44 PM
Hi Rick, depending on what you have in the hallway or room adjoining the bath will be how high you want to go. Being that there is 3/4 hardwood now, after it is removed you can go with 1/2" ply then ditra then tile.
That cx is a fast typer! :cry:

Jersey Rick
07-20-2005, 08:28 PM
Thanks guys! I'll probably go with the 1/2 inch plywood and Ditra combo just to get flush with the adjoining walk in closet. I'll keep you posted as I proceed. I've read about the shower pan install and I am waiting for the plumber to do the rough in before the heavy tiling begins. Tomorrow I'll get the floor ready for the plumber and then the Ditra. I'm sure I'll have a few questions although some of the other posts on this site have been excellent especially the one's with pictures. I'll try and keep a photographic record as well.
Yeah CX this old factory was built with some heavy timber. By the way I've book marked this post since I can see that things change very rapidly at this forum.....how do you do it! Thanks again

07-20-2005, 08:35 PM
Yep, keep it bookmarked and keep all your questions for the project on this thread. That will help us keep up. :)

How do we keep up? We've got a whole gaggle of very generous tile pros and pros of other stripes and talented amateurs who spend a whole gaggle of their free time here helping DIYers just like yourownself.

And we thank them every one every chance we get. :)