Subfloor question under slate tile.........


Old 03-11-13, 09:33 AM
Thread Starter
Join Date: Mar 2013
Posts: 2
Received 0 Votes on 0 Posts
Subfloor question under slate tile.........

Hi everyone. First post here......been lurking for a while. I'm currently renovating my bathroom and am planning to install slate tile flooring. The bathroom sits on 2x10 spf floor joists, 16 inches on center and (being an older house) the subfloor is 1x6 tongue and groove slats. The total span of the joists is a little over ten feet......What's the minimum I should beef up the subfloor with in order to prevent deflection that might cause future cracking of grout and/or tiles..........any advice welcome. Cement board vs Ditra?.........Cheers
Sponsored Links
Old 03-11-13, 09:44 AM
Thread Starter
Join Date: Mar 2013
Posts: 2
Received 0 Votes on 0 Posts
Forgot to mention - the tiles I'm planning to use are 12x12......
Old 03-11-13, 09:52 AM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,571
Received 94 Votes on 83 Posts
Welcome to the forums.

Hang tight for the pros but I don't think you have enough structure under your floor; natural stone takes a lot more than ceramic does.
Old 03-11-13, 01:05 PM
Join Date: May 2007
Location: USA
Posts: 1,607
Received 0 Votes on 0 Posts
Hi Billy & Mitch,

If the joists are in good condition with no large holes cut into them and are grade #2 or better, on paper your joists are good for natural stone tiles.

If the 1x6" planks are in good shape and not warped or cupped, you can get away with 1/2" underlayment grade ply rated exposure 1 or equivalent. Do not use cheap CDX sheathing. Thicker is always better, consider 5/8".

After the underlayment is installed per standards, I'd use Ditra, but any CBU set into thinset and taped will work fine too.

Old 03-22-13, 01:46 PM
Banned. Rule And/Or Policy Violation
Join Date: Mar 2013
Posts: 4
Received 0 Votes on 0 Posts

With a natural stone install the Tile Council of North America recommends 2 layers of tongue and groove plywood being offset from one another.

Method F250 - Interior Floors Over Wood - Joists 16" o.c./Plywood Subfloor/Plywood Underlayment/Backer Board/Natural Stone Tile - The Tile Council of North America

I would use ditra as it is superior to CBU.

I would also recommend using Power Grout.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: