Plywood Over Existing Subfloor - Not Glued? - Flooring - DIY Chatroom Home Improvement Forum

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Flooring


Thread Tools Display Modes
Old 10-13-2010, 03:56 PM   #1
Join Date: Jul 2007
Posts: 405
Rewards Points: 270

plywood over existing subfloor - not glued?

been reading a lot of the posts here on floor prep and tiling. I want to tile my bathroom - right now new construction with 5/8 t&g over 2x12 joists 16" o/c. The bathroom is @ 8'x8' at one end of the 13' joist span. Joists are also blocked mid point. The floor is very solid.

from what I gather so far I should lay down another 1/2" exterior grade ply over the existing subfloor, then my heat mesh and thinset or SLC, then backer (Ditra? - everyone raves about it and I think I can buy it by the foot here now) - then thinset + tile (probably porcelain).

question - I'm thought I read in a couple threads that the 1/2" ply should not be glued down to the subfloor, and should also not be screwed directly into the joists. Do I have this right, and if so, what's the reason? I would have guessed that glue and screw, with long screws right into the joists would be strongest. But I'm a bathroom floor tile newbie so I just want to get it right.

the easiest approach would be to staple down the heat mesh and thinset + tile right over top of the existing subfloor - but I got a feeling I'm cutting way too many corners that way.

thanks for any info / advice...


rtoni is offline   Reply With Quote
Old 10-13-2010, 04:58 PM   #2
Civil Engineer
Join Date: Mar 2009
Location: Boston
Posts: 5,688
Rewards Points: 4,956

Check out the Schluter website (they make the Ditra). They have an excellent manual on proper installation procedure for their product, including details about floor prep, installation of subfloor, installation of electric floor heat etc. I believe they indicate that the second layer of subfloor should not be attached to the joists, I can't remember the reason, but when I did my floor I remember reading this point. It was not applicable in my case since the second layer of plywood was already installed.


Daniel Holzman is offline   Reply With Quote
Old 10-13-2010, 05:53 PM   #3
Registered User
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526

If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
17,000 dryer fires a year, when did you last clean the inside of the dryer near motor or the exhaust ducting?
Gary in WA is offline   Reply With Quote
Old 10-14-2010, 11:37 AM   #4
Join Date: Jul 2007
Posts: 405
Rewards Points: 270

Daniel / GBR - got both docs - excellent - thanks very much.
rtoni is offline   Reply With Quote

Thread Tools
Display Modes

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
join new crawl space CMU footing/foundation to existing CMU basement wall CapeCod153 Building & Construction 4 08-04-2010 07:35 PM
Tile over existing floor tile radient with electric heat brownieruf Off Topic 7 05-22-2010 06:49 PM
Shear around existing window joside Carpentry 3 05-10-2010 09:04 PM
It is hard to find 1/2 t and G plywood so would regular plywood be ok ? dewi Flooring 14 05-04-2010 12:05 PM
cutting plywood panels w circular saw Klawman Carpentry 11 12-11-2009 01:40 PM

Top of Page | View New Posts


Search Engine Friendly URLs by vBSEO 3.6.1