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 08-14-2019, 03:49 PM   #1
makemenuconfig
Registered User
 
Join Date: Aug 2019
Posts: 7
Help me fix my tub-to-backer transition

Hi, I've been reading for quite some time but finally have a question to talk through with you all.

I am working on a bathroom remodel in my own house. The acrylic tub has been set in mortar and is quite sturdy, It is screwed into the studs through the flange. I know there's a mixed opinion on whether to overlap the substrate over the tiling flange, or to end it above with a gap. I chose the latter to better tie into the adjacent drywall. I plan to waterproof with Aquadefense/RedGard but have not done so yet.

I got the 1/2" cement board installed and used thinset and mesh tape on the joints. I had read to thinset and mesh-tape across the transition between the tiling flange and the bottom of the cement board.

Now yesterday I was hanging some drywall on the ceiling above the tub and had to step on the front apron / back ledge to reach some screws. I have done this a few times without issue. When I was standing there this time, I heard a small crack sound. I went to investigate and see a tiny crack in the thinset at the tiling flange. If I push hard on the front edge of the tub, I see the tub moving slightly behind the thinset like the thinset separated from the flange. Not sure if I am describing that well enough.

The front edge of the tub flexes a little since the bottom of the apron isn't quite touching the subfloor. It needed to be this way to level the tub. Now this is a separate issue, but I was thinking of either shimming the bottom of the apron or getting a little thinset under there when I tile the floor. The feet of the tub rest on the floor and the tub is level.

My main question is what to do about the backer-tiling flange transition. I am worried about leaving it as-is considering it seems the thinset came loose from the flange in this one spot. I am worried about it not holding up over time as the tub undoubtedly flexes as people get in and out, fill it with water, etc. I was considering re-doing the flange transition with kerdi-band. I assume kerdi-fix to bond the tiling flange to the kerdi-band and modified thinset to bond the kerdi-band to the cement board.

Are there any tips for removing the thinset in this area? Do you have other ideas for how to transition from cement board to tiling flange?

Thanks!
Attached Images
   
__________________
Evan

Last edited by makemenuconfig; 08-14-2019 at 03:58 PM. Reason: Photos appeared sideways
makemenuconfig is offline   Reply With Quote
Sponsored Links
Unread 08-14-2019, 04:30 PM   #2
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 89,783
Welcome, Evan.

The only good method I've seen for dealing with that junction when using a direct bonded waterproofing membrane on your walls is to use a strip of a sheet-type membrane that you can bond to the tub's tiling flange and to your wallboard. Preferably with even a tiny bit of a wedgie in the gap for movement accommodation. If you'll go to the Schluter Kerdi website and download the Installation Handbook you'll see (I think on page 34 these days) a very good depiction of the procedure for that.

While you can probably do that with a liquid-applied membrane and a reinforcing fabric, I'd really recommend you get a strip of either the Kerdi membrane or the USG Durock Shower System membrane to use for the purpose. The USG product is easily found on Amazon, even. Kerdi Fix is very good for the adhesive to the tub flange, or you could use something similar, like SikaFlex, from your local home center. 100 percent silicon might also suffice, but would not be my first choice. You'll bond to the CBU with thinset mortar.

Your thinset mortar is not gonna bond with the tub flange and even if it did the mortar would not allow for any movement at all. And there will be movement there as you've seen. Cutting out the mortar and mesh tape in that area should not be a difficult task.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is offline   Reply With Quote
Unread 08-14-2019, 10:56 PM   #3
ZZZK
Registered User
 
Join Date: Mar 2016
Posts: 426
The way I handled it in my hydroban waterproofed tub area is the following.

Hung cement board with a 3/16" ish gap above tub rim to allow for movement. The acrylic tub (MTI) had a 1/16 factory bonded tub flange that is designed to go behind the wall board. I shimmed the studs above tile flange 1/16 to make up for tile flange thickness.

I carefully cleaned the tub deck with denatured alcohol. I then blue taped the tub deck leaving only the area directly under the wall board exposed. I then carefully pumped this gap full of plenty of hydroban sealant. I immediately tooled the sealant with a straight edge insuring the gap was well filled with no holes and flush. Immediately pull away the tape. You should now have a pefectly filled gap between wallboard and tub deck that allows for tub movement. Allow sealant to fully cure.
I then taped the tub deck again putting the edge of the tape right up the sealant bead. I then waterproofed the cement board with hydroban liquid membrane and used a brush to fully cut the hydroban in all the way to the tub deck. Hydroban is painted over the hydroban sealant. Immediately pull up the tape before the hydroban cures.
Repeat for 2nd coat.

When you tile leave a similar sized movement gap with tile and tub deck. Fill this gap with 100% silicone in your desired color. Do not grout this gap! Grout will transfer movement to your tile installation.


What you did there is a no no as per CX. Thinset will not stick to that tub and that fibertape is not doing anything. Further you need to have a movement joint there and the thinset does not provide that.
__________________
John
ZZZK is offline   Reply With Quote
Unread 08-16-2019, 09:22 AM   #4
makemenuconfig
Registered User
 
Join Date: Aug 2019
Posts: 7
Thanks all for the advice, this sounds like a plan. I'll have a go at removing the thinset and mesh tape and will use kerdi-band with kerdi-fix on the tub and unmodified thinset on the CBU. Schluter has a great video demonstrating this technique.

Everywhere I look people say you shouldn't mix systems because there's no reason to and you loose any warranty. But I'm not particularly interested in using kerdi in the whole surround and still want to use aquadefense. Can I just go over the kerdi-band transition down to the tub with aquadefense? I know neither company tests this scenario. I don't want to set myself up for failure, but I'm not seeing why this would be an issue unless one of the materials won't bond to the other.
__________________
Evan
makemenuconfig is offline   Reply With Quote
Unread 08-16-2019, 09:42 AM   #5
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 89,783
Should work fine, but I'd recommend you apply your HydroBan to the walls first, then apply your KerdiBand to the wall/tub flange junction.

We know the thinset mortar (I'd use a modified mortar) will bond the KerdiBand to the HydroBan, but I'd be less confident of the bond between HydroBan and the KerdiBand. Up to you.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is offline   Reply With Quote
Unread 08-19-2019, 02:58 PM   #6
makemenuconfig
Registered User
 
Join Date: Aug 2019
Posts: 7
Got the thinset removed; took less than an hour to do. It chipped off the flange fairly easily, but was pretty tight between the flange and backer board.

Doing the liquid membrane first makes sense in my head but kind of feels backwards to me. I ended up making a mockup test this weekend. I took a piece of kerdi and coated it with aquadefense, leaving an area masked with blue tape to give me a corner to start peeling. I did 2 coats and left it for about 24 hours.

Peeling off the aquadefense was not easy. Once started, took moderate pressure to pull apart. The fleece completely separated from the orange kerdi leaving a smooth orange sheet behind. That would imply the bond between aquadefense and kerdi was higher than the bond between the two parts of kerdi. This test doesn't speak for the longevity of such a solution, but it does show the aquadefense can certainly grab onto the fleece fibers.

I like this solution because it gives me a complete, uninterrupted waterproofing membrane from top of the surround to the bottom of the flange like I originally wanted. I think this is sufficient, but still weighing my options.
Attached Images
    
__________________
Evan
makemenuconfig is offline   Reply With Quote
Unread 08-19-2019, 03:17 PM   #7
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 89,783
It's your shower, Evan. If you like it, use it.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is offline   Reply With Quote
Unread 11-15-2019, 12:51 PM   #8
makemenuconfig
Registered User
 
Join Date: Aug 2019
Posts: 7
4x12 ceramic running bond; will lippage be an issue?

I just successfully completed my first tile job, a porcelain large format floor in my bathroom!

I am now ready to tile the shower. We have a 4x12 porcelain tile with a slight wavy/handmade texture. The edges are definitely a little rounded, at least in comparison to the rectified porcelain I just installed.

The manufacturer recommends a minimum 1/16" grout line, I plan to use 1/8". I am trying to determine the pattern with which to arrange the tile and am having trouble. If this were a perfect non-cupped tile (ha!) I would go for a 50% running bond in a heartbeat, I love the way it looks. I know for large format tile a 50% offset can be a bad idea due to higher lippage. This isn't technically a large format tile, but it's not tiny either. I tried to face the tiles together to look for a cup. The tile does rock, but in random directions from tile to tile because of the slight overall waviness to the tile face itself. So I faced the backs together and can see a little light coming through from between. I think I could *barely* stick the corner of a credit card between the two tiles in the center.

I have can lights in the bathroom, but not over the tub so I'm not as worried about light accentuating any lippage. Do you think it is unwise to do a 50% offset with this tile? I've never done this before so I don't really know if this will be a problem. I will pick another pattern if it means a good looking job. I'd much rather have a pattern that I don't love as much than a tile job that overall looks bad.

Thanks all!
Attached Images
     
__________________
Evan
makemenuconfig is offline   Reply With Quote
Unread 11-15-2019, 03:15 PM   #9
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 89,783
Evan, I hate to be wishy-washy about it, but the only way you're going to know if you can do the 50 percent offset successfully is to set some of the tiles with a 50 percent offset and see how you like the result.


Much of the potential problem will be the flatness of your tiles. Some of the problem will be the flatness of your substrate. The third potential problem will be your setting technique. The tiles look like they might be flat enough in your photos. I dunno about your substrate. I know less about your setting abilities.

If you don't wanna test your result on your shower walls, get you a sheet of CBU or plywood and set some tiles. Grout the result and see if you like the outcome.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is offline   Reply With Quote
Unread 11-16-2019, 10:00 AM   #10
Carbidetooth
Hmmmmm
 
Carbidetooth's Avatar
 
Join Date: Mar 2010
Location: Boise, ID
Posts: 1,495
CX wishy washy? Tell me it aint so!

I confess to breaking the no 50% rule, but it was well considered. The pillowed edge on that tile and the undulating surface work in your favor. Sharp, square edges make a tile setter's job harder. Well, that and large format...and glass...and, and, well you get the idea.
__________________
Peter

Silicone (not silicon) Sealant Ranger
Carbidetooth is offline   Reply With Quote
Unread 11-16-2019, 11:30 AM   #11
makemenuconfig
Registered User
 
Join Date: Aug 2019
Posts: 7
Wishy-washy is kind of how I felt. Technically this doesn't break any TCNA rules since it is not a large format tile. I just don't have much experience looking at what is or isn't normal for cupping on a ceramic tile. I'll see how much extra I ordered and consider making a mockup.
__________________
Evan
makemenuconfig is offline   Reply With Quote
Unread 11-22-2019, 04:30 PM   #12
makemenuconfig
Registered User
 
Join Date: Aug 2019
Posts: 7
Update, success

Wanted to give an update.

I got not quite half way done on Sunday and had to stop because our hardwood floor guy could squeeze us in early. I laid out a bunch of tile on a flat surface and didn't see much of an issue, so I decided to proceed and risk it. Even though it's not grouted yet, I ended up being quite pleased with the result. There are only a couple of spots with lippage and those are 100% due to my inexperience.
Attached Images
 
__________________
Evan
makemenuconfig is offline   Reply With Quote
Unread 11-22-2019, 05:35 PM   #13
ss3964spd
Moderator
 
ss3964spd's Avatar
 
Join Date: Jul 2005
Location: Fairfax, Va
Posts: 2,966
Send a message via Yahoo to ss3964spd
Looks darn nice from here, Evan!
__________________
Dan
---------------------------------------------------------------------------------
If I recall correctly my memory is excellent, but my ability to access it is intermittent.
ss3964spd is offline   Reply With Quote
Unread 11-22-2019, 06:34 PM   #14
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 89,783
What Dan said.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is offline   Reply With Quote
Unread 11-25-2019, 09:59 AM   #15
makemenuconfig
Registered User
 
Join Date: Aug 2019
Posts: 7
Thanks, appreciate the kind words!

I am finishing this out today; and one of my tasks is the tile next to the tub apron. For many reasons it was best for me to set the schluter profile where I did. It allowed me to split a tile in half and do the 50% offset with no waste and it lines up on the opposite side exactly with an outside corner. However this leaves me with a little over 1/2 a tile below the top of the tub. If I continue the pattern perfectly this leaves a 3/4" to 1/2" sliver on every other tile here which is not great.

I could do that and live with the slivers, or I could cut a slightly large half and basically switch to a stacked pattern and hope your eye sees them as half tiles. The shower curtain will mostly cover this area, but I'd like to see what you think is the lesser of two evils. (shown at the bottom is a perfect half tile).
Attached Images
 
__________________
Evan

Last edited by makemenuconfig; 11-25-2019 at 10:14 AM. Reason: Adding photo
makemenuconfig is offline   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
How to deal with backer board/drywall transition at inside corner ryebotanist Tile Forum/Advice Board 16 10-07-2015 08:53 AM
Hardie Backer to Drywall Transition jnbrown Tile Forum/Advice Board 2 12-27-2008 10:10 PM
"joining" old backer board to new backer board alq137 Tile Forum/Advice Board 4 09-01-2008 02:50 AM
CBU transition misshurley Tile Forum/Advice Board 32 10-29-2007 09:57 PM
Transition Help andrew390 Tile Forum/Advice Board 2 06-12-2006 09:33 PM


All times are GMT -6. The time now is 04:29 PM.


Sponsors

Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright 2018 John Bridge & Associates, LLC