Can I Put Cement Board Over Drywall On A Shower Wall? - 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!

Like Tree8Likes
  • 4 Post By chandler48
  • 1 Post By chandler48
  • 1 Post By ZZZZZ
  • 1 Post By jeffnc
  • 1 Post By jeffnc
Reply
 
Thread Tools
Display Modes
Old 08-11-2019, 04:37 PM   #1
Member
 
ZZZZZ's Avatar
 
Join Date: Sep 2014
Location: Middle of nowhere, AZ
Posts: 7,695
Rewards Points: 2,110
Default

Can I put cement board over drywall on a shower wall?


I am remodeling one of my bathrooms and I need some clarification as to how to proceed.

The bathroom has a standard bathtub but for whatever reason the original homeowner did not install a shower above the tub. Apparently they only used it as a bathtub.

I have now added a shower valve, diverter, etc and am ready to tile the tub area.

The existing walls surrounding the tub are standard drywall and obviously I shouldn't tile directly on the drywall.

My question is, can I install cement board over the drywall, and then waterproof the cement board with RedGard (or something similar) and then tile?

I'd rather not take the time and make the mess to remove the drywall and install the cement board directly to the studs as would be the usual process.

There is nothing behind the drywall other than fiberglass insulation bats.

Thanks.
.
.
__________________
Just my 7 cents (2 cents after taxes and inflation).

Last edited by ZZZZZ; 08-11-2019 at 04:40 PM.
ZZZZZ is online now   Reply With Quote
Sponsored Links
Advertisement
 
Old 08-11-2019, 05:35 PM   #2
Naildriver
 
chandler48's Avatar
 
Join Date: Jun 2017
Location: Young Harris, Georgia
Posts: 6,584
Rewards Points: 3,530
Default

Re: Can I put cement board over drywall on a shower wall?


Check the pricing of Ditra membrane. You can put it on and save some space. Otherwise it will be best to remove the sheetrock in the shower area and replace it with 1/2" Durock or Hardie Backer.

You'll want your CBU to sit on the vertical lip of the tub. Your tile will extend down to the tub curve to keep water from wicking up.
Attached Images
 
ZZZZZ, Yodaman, ktownskier and 1 others like this.
__________________
Larry......
Half of Communications is Listening, and You can't Listen with your Mouth.
chandler48 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 08-11-2019, 08:23 PM   #3
Member
 
ZZZZZ's Avatar
 
Join Date: Sep 2014
Location: Middle of nowhere, AZ
Posts: 7,695
Rewards Points: 2,110
Default

Re: Can I put cement board over drywall on a shower wall?


Thanks Chandler.

So Ditra can go directly over drywall?

It is expensive, about $2 a sf.

That's a lot more than I paid for the tile.
.
.
__________________
Just my 7 cents (2 cents after taxes and inflation).
ZZZZZ is online now   Reply With Quote
Sponsored Links
Advertisement
 
Old 08-11-2019, 08:27 PM   #4
Naildriver
 
chandler48's Avatar
 
Join Date: Jun 2017
Location: Young Harris, Georgia
Posts: 6,584
Rewards Points: 3,530
Default

Re: Can I put cement board over drywall on a shower wall?


Yeah, that is why I prefaced my statement. Ditra is expensive, but figure your labor cost to remove the sheetrock, install the CBU, seam it and RedGard areas needing it. Red Gard is about $45 a gallon alone. Justify the cost difference.
ZZZZZ likes this.
__________________
Larry......
Half of Communications is Listening, and You can't Listen with your Mouth.
chandler48 is offline   Reply With Quote
Old 08-11-2019, 08:54 PM   #5
Remodel and New Build GC
 
MTN REMODEL LLC's Avatar
 
Join Date: Sep 2010
Location: Colorado @ 7651'
Posts: 7,847
Rewards Points: 1,998
Default

Re: Can I put cement board over drywall on a shower wall?


ZZZZZZZZZZZ.....

Let us know how you figure and decide....

Seems at a gut to me, that a little rock tearout and a vapor barrier and CBU is easier/more economical.... maybe not.

I don't redguard any vertical CBU.
__________________
Never stop learning (xcep fer speling en typeing)
MTN REMODEL LLC is offline   Reply With Quote
Old 08-12-2019, 12:33 AM   #6
Member
 
ZZZZZ's Avatar
 
Join Date: Sep 2014
Location: Middle of nowhere, AZ
Posts: 7,695
Rewards Points: 2,110
Default

Re: Can I put cement board over drywall on a shower wall?


Quote:
Originally Posted by chandler48 View Post
Yeah, that is why I prefaced my statement. Ditra is expensive, but figure your labor cost to remove the sheetrock, install the CBU, seam it and RedGard areas needing it. Red Gard is about $45 a gallon alone. Justify the cost difference.
Quote:
Originally Posted by MTN REMODEL LLC View Post
ZZZZZZZZZZZ.....

Let us know how you figure and decide....

Seems at a gut to me, that a little rock tearout and a vapor barrier and CBU is easier/more economical.... maybe not.

I don't redguard any vertical CBU.
Ditra it will be. It's "only" $1.40/SF on ebay and Amazon, shipped.
.
.
chandler48 likes this.
__________________
Just my 7 cents (2 cents after taxes and inflation).

Last edited by ZZZZZ; 08-12-2019 at 12:37 AM.
ZZZZZ is online now   Reply With Quote
Old 08-12-2019, 07:16 AM   #7
Member
 
Join Date: Apr 2011
Location: North Carolina, USA
Posts: 4,710
Rewards Points: 5,662
Default

Re: Can I put cement board over drywall on a shower wall?


Ditra is NOT used for shower walls. The product to use is Kerdi. In the small quantity rolls you'll be buying, the price will be similar per sf. It is usually most convenient to use Kerdi Band as well, but you can get by without it if you know what you're doing.


The process will match the earlier picture posted above, except with no backer board, and Kerdi instead of vapor barrier (Kerdi is a kind of vapor barrier.) Instead of silicone caulk sealing the Kerdi to the tub, you would use a caulk such as Kerdi Fix. This is the one the company recommends of course, because it is theirs, but it's very expensive. I would use a different polyurethane caulk just based on availability and price of Kerdi Fix. I usually use https://www.lowes.com/pd/BASF-NP1-10...ulk/1000002916 (prefer white color)
ZZZZZ likes this.

Last edited by jeffnc; 08-12-2019 at 07:25 AM.
jeffnc is offline   Reply With Quote
Old 08-12-2019, 05:40 PM   #8
Naildriver
 
chandler48's Avatar
 
Join Date: Jun 2017
Location: Young Harris, Georgia
Posts: 6,584
Rewards Points: 3,530
Default

Re: Can I put cement board over drywall on a shower wall?


Jeff's right. I misspoke regarding the different applications. Kerdi for walls and Ditra for floors. Duh.
__________________
Larry......
Half of Communications is Listening, and You can't Listen with your Mouth.
chandler48 is offline   Reply With Quote
Old 08-12-2019, 06:24 PM   #9
Member
 
ZZZZZ's Avatar
 
Join Date: Sep 2014
Location: Middle of nowhere, AZ
Posts: 7,695
Rewards Points: 2,110
Default

Re: Can I put cement board over drywall on a shower wall?


They're both orange, right?


.
.
__________________
Just my 7 cents (2 cents after taxes and inflation).
ZZZZZ is online now   Reply With Quote
Old 08-13-2019, 12:33 AM   #10
Member
 
ZZZZZ's Avatar
 
Join Date: Sep 2014
Location: Middle of nowhere, AZ
Posts: 7,695
Rewards Points: 2,110
Default

Re: Can I put cement board over drywall on a shower wall?


Related question:

The drywall in the tub/shower area is painted with a semigloss on knock-down texture.

How should I prepare the drywall to ensure maximum adhesion of the Kerdi mortar?

What came to my mind was to do a skim coat of the wall with drywall mud and prime it. Good or bad idea? Other suggestions?

Thanks.
.
.
__________________
Just my 7 cents (2 cents after taxes and inflation).
ZZZZZ is online now   Reply With Quote
Old 08-13-2019, 12:58 AM   #11
Member
 
Join Date: Apr 2011
Location: North Carolina, USA
Posts: 4,710
Rewards Points: 5,662
Default

Re: Can I put cement board over drywall on a shower wall?


You can either sand it down or skim coat it smooth. Priming isn't necessary.
ZZZZZ likes this.
jeffnc is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply



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





Top of Page | View New Posts