Bathroom Wall, Is CBU Directly Over Plywood OK? - Kitchen & Bath Remodeling - DIY Chatroom Home Improvement Forum
Advertisement


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Remodeling > Kitchen & Bath Remodeling

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools
Display Modes
Old 02-17-2016, 07:02 PM   #1
Newbie
 
Join Date: Feb 2016
Posts: 7
Rewards Points: 14
Default

Bathroom Wall, Is CBU directly over plywood OK?


Hello all, first timer here. I'll keep it to the point.

Old-ish house (early 1970s), discovered plywood on all three walls surrounding shower when removing old tile. Can I just screw CBU directly over this old plywood without using thinset in between?

Thank you for any responses!

Last edited by ChuckHammer; 02-17-2016 at 07:12 PM. Reason: oddly stated sentence
ChuckHammer is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 02-17-2016, 08:56 PM   #2
Member
 
jproffer's Avatar
 
Join Date: Mar 2005
Location: Chester, IL
Posts: 1,631
Rewards Points: 306
Default


I wouldn't. The thinset is meant to fill any voids behind the CBU. If you leave it out, and if the plywood isn't perfectly flat (which it probably isn't), the wall could flex and crack the tile and/or grout.
jproffer is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 02-17-2016, 09:16 PM   #3
Newbie
 
Join Date: Feb 2016
Posts: 7
Rewards Points: 14
Default


jproffer. Ok. Then I need to remove all the old plywood and sister new studs to the old studs to get back the 1/2 in of plywood (actually more than 1/2 in). I was trying to avoid having to do this. Thanks.
ChuckHammer is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 02-17-2016, 09:23 PM   #4
Member
 
jproffer's Avatar
 
Join Date: Mar 2005
Location: Chester, IL
Posts: 1,631
Rewards Points: 306
Default


I dunno about that....

If the plywood is in good shape and tight, thinset and CBU over the top of it. On a wall, flex isn't such a problem, but it's still possible.
jproffer is offline   Reply With Quote
Old 02-17-2016, 10:03 PM   #5
Newbie
 
Join Date: Feb 2016
Posts: 7
Rewards Points: 14
Default


You're right, it's not high quality ply. I think I'm going to remove it. What I didn't mention was that on top of the plywood was 1/2" drywall, then on top of the drywall was some kind of board I had no idea what it was (1/2" as well). I took a piece of it to my local hardware store and they didn't know what it was either. It is brown in color and crumbled like a kind of clay. On top of this mystery material was the tile. So I need to add 1" of furring or add sister studs to get flush with the wall. Leaving the old ply in would make an easier job.
ChuckHammer is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply


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
need bathroom shower/tub ideas recklessrick Plumbing 0 01-12-2013 12:51 PM
Water issue in bathroom at base of the tub and shower plumbing wall NeverEnoughTime Plumbing 3 10-24-2012 11:23 PM
Avoiding load on inner, exterior wall jklingel Building & Construction 2 06-04-2011 01:35 PM
New foundation for bathroom floor and exterior wall studs JayG Building & Construction 2 07-11-2010 01:25 PM
Removing spine wall beko Building & Construction 12 02-02-2010 01:15 AM




Top of Page | View New Posts