Ceramic Tile Advice Forums - John Bridge Ceramic Tile

Welcome to John Bridge / Tile Your World, the friendliest DIY Forum on the Internet


Advertiser Directory
JohnBridge.com Home
Buy John Bridge's Books

Go Back   Ceramic Tile Advice Forums - John Bridge Ceramic Tile > Tile & Stone Forums > Tile Forum/Advice Board

Sponsors


Reply
Thread Tools Search this Thread
Unread 09-23-2023, 07:34 AM   #1
ScreamerDog
Registered User
 
Join Date: Sep 2023
Posts: 5
Shower Large Tile and Kerdi Band/Fix

Couple questions.

1. Using Mapei Large Format Tile Mortar - Polymer Enriched. I would like to use Kerdi Band on both the shower flange to Hardie Board joint and the pipe seals from Schluter. Question is as long as time is given for this mortar to dry before Aquadefense is applied whether it is fine to use this Modified mortar with Kerdi Band/pipe seals...? Should the mortar on the outside just be treated like a scratch coat or sponged off clean before Aquadefense...? Just doesn't make sense to use unmodified and then modified mortar for large tiles. Otherwise why use the band/seal at all...?

2. The shower pan flange is tucked into the frame so the Hardie Board can go over the flange. To waterproof the joint, the plan is to apply Aquadefense to the acrylic and let dry before adding more Aquadefense to a vapor barrier. The question is what is the best technique to seal the joint...? I've seen others use fiberglass tape and just use Aquadefense or Kerdi Fix to fill the joint. Should the liquid membrane be applied to the Hardie Board and dry before sealing the joint...?

3. Vapor Barrier and moister sandwich. If the liquid membrane is applied properly no water or moisture should get behind the Hardi Board. Would using a vapor barrier up 3-4 feet minimize the sandwich or just avoid using a vapor barrier behind all together...?

Sorry if these topics have been discussed thoroughly before. I would appreciate any and all advice/suggestions. Thanks, John - Pennsylvania
__________________
John
ScreamerDog is offline   Reply With Quote
Sponsored Links
Unread 09-23-2023, 08:55 AM   #2
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 98,197
Welcome, John.

1. I would not use an LHT mortar to apply any sheet-type waterproofing membrane, but you can if you like. As for it being a modified mortar, the Hardiebacker manufacturer requires a modified thinset mortar (ANSI A118.4) for bonding to the product.

2. I'm a bit confused here. In #1 you indicated that you would use KerdiBand to seal "the shower flange to Hardie Board joint," but now you indicate that the wallboard will lap over the receptor tiling flange. Which is it?

If your wallboard laps over the tiling flange on the drain side, there is no need to seal the joint between wallboard and receptor at all and I would not. Hold the wallboard 1/8th" above the receptor and seal the face of the wallboard with your liquid-applied waterproofing membrane and call it done.

3. There is no need for any moisture barrier behind the wallboard if you're using a direct bonded waterproofing membrane (ANSI A118.10) on the face of the wallboard. You can use either one, but not both.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!

Last edited by cx; 09-23-2023 at 01:31 PM. Reason: typo
cx is online now   Reply With Quote
Unread 09-23-2023, 01:32 PM   #3
ScreamerDog
Registered User
 
Join Date: Sep 2023
Posts: 5
Shower Large Tile and Kerdi Band/Fix

CX, thanks for responding. Hopefully this clarifies some of the items discussed.

1. Overall my point is trying to narrow down the best method to embed the pipe seal membrane. As you indicated any membrane should go directly to the hardie board with mortar before aquadefense or kerdi fix. The membrane could also be embedded to the hardie board with either aquadefense or kerdi fix only without mortar. Seems either aquadefense and/or kerdi fix would embed into hardie board better than either modified or unmodified mortar. Why use any mortar to embed membrane...? Regardless, after the membrane is embedded into the hardie board, aquadefense would be applied to the entire shower walls before modified mortar is used for large tiles.

2. The flange seal is more difficult to explain. The hardie board will overlap the acrylic flange. However, seems one would still need to use a vapor barrier, even if only 12 inches above the flange just to seal any water from getting behind the shower pan/flange. Similar to #1 discussion, whether kerdi band or fiberglass tape is used for the flange joint, aquadefense or kerdi fix could be used to seal the joint. Since the hardie board is already overlapped, do you think it is not necessary to use kerdi band or fiberglass tape to seal the joint...? Would the liquid membrane only be sufficient to seal joint...?

3. Clarification for vapor barrier, I'm not suggesting using a vapor barrier all the way up the wall to the ceiling. Seems one should be used though from the studs to the shower flange.

Again, thanks for any response. John
__________________
John
ScreamerDog is offline   Reply With Quote
Unread 09-23-2023, 02:55 PM   #4
jadnashua
Veteran DIYer- Schluterville Graduate

STAR Senior Contributor

 
Join Date: Jul 2004
Location: Nashua, NH
Posts: 15,807
FWIW, HardieBacker is extremely thirsty, so it will suck up any moisture from your mortar. The issue with modified mortars and waterproofing is that some (very few these days) modified mortars need to dry to become stable. The curing process occurs regardless of whether it is still wet or not.

If you're going to use a waterproofing on top of the CBU, you do not want one behind it.

With say RedGard over Hardiebacker, they require you to apply a thinned out first coat as a primer...I do not know if AquaDefense has a similar precaution. The reason is that as noted earlier, HardieBacker is extremely thirsty, and can mess with the proper function of the waterproofing before it gets a chance to properly 'set'.

Industry guidelines call for a vapor barrier either behind the CBU, or waterproofing on top of it, but not both. It depends on the construction method you choose.
__________________
Jim DeBruycker
Not a pro, multiple Schluter Workshops (Schluterville and 2013 and 2014 at Schluter Headquarters), Mapei Training 2014, Laticrete Workshop 2014, Custom Building Products Workshop 2015, and Longtime Forum Participant.
jadnashua is offline   Reply With Quote
Unread 09-23-2023, 06:25 PM   #5
jonchicagoland
Registered User
 
Join Date: Nov 2022
Location: Aurora IL
Posts: 67
Regarding applying band and seals - I would not use AquaD to apply your Kerdi - I think that's asking for trouble. Either mortar or Kerdifix. From a pro perspective, the reason to use mortar is because Kerdifix is comparatively very expensive, and mortar is usually getting mixed up anyways.
__________________
Jon
Aurora IL
https://rippedjeansconstruction.com
jonchicagoland is offline   Reply With Quote
Unread 09-23-2023, 07:29 PM   #6
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 98,197
1. And mortar is what's required by the Kerdi manufacturer and the CBU manufacturer. The liquid-applied waterproofing membranes are not intended to be used as adhesives. Not a wheel that needs any reinvention. If you wanna mix and match your waterproofing membranes otherwise, that's of course up to you.

As for the fabric pipe and valve seals, you can certainly use those if you want, but I'd install them per the manufacturer's instructions. I've never used one. Before Schluter started making them for their Kerdi line, they recommended you simply coat the edges of your drywall openings with 100 percent silicone after installing your Kerdi membrane.

2. Again, you can do what you like, but I wouldn't seal that joint at all, nor would I coat the bottom edge of the CBU with your liquid-applied membrane. If you think the 1/8th" gap is not enough, leave a 1/4" gap. Your tile surface will come down to within 1/8th" and you cover that gap with a flexible sealant. While moisture can certainly get behind the tile, there will be no standing water to wick up your CBU wallboard.

If you just feel better with moisture barrier membrane behind the bottom of your wallboard, feel free to do that, but you still don't want to try to seal the gap between wallboard and shower receptor with the membrane in there.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is online now   Reply With Quote
Unread 09-24-2023, 10:33 AM   #7
ScreamerDog
Registered User
 
Join Date: Sep 2023
Posts: 5
Thanks again for the responses. I found this link that shows sort of what I'm suggesting. Joe Letendre "So that's how you do that" uses hydroband to completely seal the flange with fiberglass tape.

I'm suggesting using a 2 foot vapor barrier sealed the studs and shower flange with aquadefense. I would also think pre-sealing the hardie board with aquadefense a couple inches on the bottom back including the bottom edge would work. Let dry, then seal the joint with more aquadefense and either kerdi band or fiberglass tape similarly to this link. Overkill I guess but thats what I'm trying to do...

youtu.be/icyor45wyCs?feature=shared
__________________
John

Last edited by cx; 09-24-2023 at 03:56 PM. Reason: Add Link
ScreamerDog is offline   Reply With Quote
Unread 09-24-2023, 12:06 PM   #8
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 98,197
Your link takes me to a YouTube video on how to share YouTube videos, John.

Be careful when you think you're providing overkill that you're not simply committing kill.

I would not seal the bottom edge of your CBU because that is the only collecting and exiting point for any liquid water that might form from water vapor in your CBU wall. Will you have some water in the CBU? Yes. Will it be a problem if you seal the bottom of your CBU? I dunno, but why find out?

Especially if you put your moisture barrier behind the lower portion of your CBU and allow it to lap over the tiling flange on the drain side. You've already got your overkill in place if you do the moisture barrier. A foot high would be more than adequate.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is online now   Reply With Quote
Unread 09-24-2023, 01:40 PM   #9
ScreamerDog
Registered User
 
Join Date: Sep 2023
Posts: 5
Sorry, newbie here and unable to add links unless the http was removed. Here is the title for the video.

PROBLEM SOLVED for Tub Flange when Installing Cement Board and Tile

Maybe this link will work.

https://www.youtube.com/watch?v=icyor45wyCs
__________________
John
ScreamerDog is offline   Reply With Quote
Unread 09-24-2023, 04:07 PM   #10
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 98,197
Yeah, I had tailored your previous link and found the video, John. All I can say for that is ol' Joe isn't much on following product manufacturers' instructions. If you should elect to do your tub the way he shows in his video, I hope you'll at least read the HydroBan instructions as he pretty clearly did not, using a single coat over some mesh tape to cover that wallboard/tub gap.

But that really isn't at all meaningful in your application where you have installed your wallboard covering the tiling flange.

But, again, listen to whomever you like and waterproof your installation in whatever manner makes you comfortable.

My opinion; worth price charged.

PS: I also like the part where he says that if you use KerdiBoard he guarantees you'll never have a cracked tile, but that's another discussion, eh?
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is online now   Reply With Quote
Unread 09-24-2023, 04:17 PM   #11
ScreamerDog
Registered User
 
Join Date: Sep 2023
Posts: 5
Yepper, thanks. I just found the accomplice for what I was thinking...ha. I do need to make a decision soon though. Replacing a terracota p-trap on a main sewer has turned into a complete bathroom redo and now figuring out these details. Thanks for the help and directions. I will share my finished product over the next couple weeks.
__________________
John
ScreamerDog is offline   Reply With Quote
Unread 09-24-2023, 05:09 PM   #12
Snets
Professional Weekend Warrior
 
Snets's Avatar
 
Join Date: Dec 2008
Location: Northern California
Posts: 894
Quote:
Originally Posted by CX
2. Again, you can do what you like, but I wouldn't seal that joint at all, nor would I coat the bottom edge of the CBU with your liquid-applied membrane. If you think the 1/8th" gap is not enough, leave a 1/4" gap. Your tile surface will come down to within 1/8th" and you cover that gap with a flexible sealant. While moisture can certainly get behind the tile, there will be no standing water to wick up your CBU wallboard.
TCNA B412-22 is the industry standard that covers the installation you are working on - a pre-fabricated shower receptor with a flange, where your CBU is installed over the flange. The industry standard calls for exactly what CX has described a couple times here: CBU installed over the flange with a 1/4” gap above the deck, a waterproof membrane either over the CBU OR a vapor barrier behind the CBU (overlapping the flange) and a flexible sealant between the receptor and the installed tile. There should be no seal between your CBU and the receptor flange.

You can Google “TCNA 412-22” and find a drawing as well as some of the language for the industry standard installation for your situation. The TCNA Handbook is copyrighted so I’m not going to post a copy of the pages.

Like CX said, if you want to mix and match a bunch of products and installation methods, your choice. Good advice is to follow industry standards.
Snets is offline   Reply With Quote
Unread 09-24-2023, 05:53 PM   #13
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 98,197
Glad they agree with me about something occasionally, John.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is online now   Reply With Quote
Reply

Stonetooling.com   Tile-Assn.com   National Gypsum Permabase


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Kerdi Band and Patches on Kerdi Board - Effect on 3x6 Subway Tiles? Rexiepo Tile Forum/Advice Board 18 03-29-2018 11:16 AM
Installed Kerdi-band over Kerdi-board but thinset seems fragile. Bonobo Tile Forum/Advice Board 7 03-14-2014 06:41 PM
Adhesives question: Swanstone, Kerdi band, Kerdi aluminum edge profiles keithwwalker Tile Forum/Advice Board 8 02-19-2012 08:54 AM
Putting large tile on Kerdi shower wall ruthie_remodels Tile Forum/Advice Board 8 09-11-2006 05:42 PM


All times are GMT -6. The time now is 10:14 PM.


Sponsors

Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.
Copyright 2018 John Bridge & Associates, LLC