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 10-17-2020, 03:01 PM   #1
SC2020
Registered User
 
Join Date: Oct 2020
Posts: 11
Flaking Mortar Bed

Hi,
New to the forum, thanks for having me. I’m renovating my bathroom and installing a 34” x 34” shower. I’ve tiled floors in the past with no issues but this is my first time prepping and tiling a shower. I’ve read a lot of posts and watched several videos while I move along through the project. I mixed my preslope bed as instructed with a 5:1 sand to Portland ratio and sloped 1/4” per ft and everything went just fine. I installed the Oatey 40 mil pan liner as per the directions with no issues, then I mixed my mortar for the final bed at the same 5:1 ratio. I laid the bed starting from the perimeter and worked my way towards the drain, the bed ended up slightly over 1 1/2” thick. Everything seemed to setup fine until around 72 hours later when I rubbed my hand over the mortar bed and the top layer seems to flake/crumble. I’ve read a few posts of people who’ve had a similar issue and the responses range from grab a hammer and redo it to it’s fine just go over with a coat of thin set.

The crumbling is not as bad as other posts where they say it goes down 1/4” or more, it’s more just the top layer flaking off. There are no cracks and it’s solid to stand on. My original plan before this hurdle was to go over everything with Redgard before tiling. My fear is obviously the tile won’t stay adhered if the floor is crumbling. Any advice would be much appreciated!

Thanks!
Attached Images
 
__________________
SC
SC2020 is offline   Reply With Quote
Sponsored Links
Unread 10-17-2020, 04:57 PM   #2
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 91,233
Welcome, SC.

Not at all uncommon for deck mud to be a little sandy on top when cured, 'specially if you don't cover it with Poly or similar while it's curing. The top doesn't really cure properly because it tends to dry first. Usually not a structural issue for a shower receptor.

Please don't coat that floor with RedGard or similar. You're building a traditional receptor and part of the design is for the top mud be to allow moisture to pass through it easily and reach the drain's weep holes or dry by evaporation through the tile surface. Your RedGard would prevent some of that, but it will not keep water from getting into the mud bed, it'll only keep it from evaporating out again.

Use one waterproofing, correctly installed, and only one. That traditional waterproofing method has been working just fine for many, many decades. It's a wheel that doesn't need reinventing, nor even any improvement.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is online now   Reply With Quote
Unread 10-17-2020, 05:30 PM   #3
SC2020
Registered User
 
Join Date: Oct 2020
Posts: 11
Thank you for the advice CX, again much appreciated and I’m glad I asked the question before the Redgard application! I have also read on posts with similar situations that the responses suggest a coat of thin set to “help tighten” the mortar bed up before the actual thin set and tile is installed. Is there any legitimacy or value to this step? Or just Redgard the CB walls and proceed with the tiling?
__________________
SC
SC2020 is offline   Reply With Quote
Unread 10-17-2020, 06:11 PM   #4
Davy
Moderator -- Mud Man
 
Davy's Avatar
 
Join Date: Jan 2003
Location: Princeton,Tx.- Dallas area
Posts: 32,884
On shower floors where the mud wasn't mixed properly, sometimes the installer will add a skim coat to the mud bed to keep it from eroding on the surface. Or, if a mud bed isn't going to be tiled right away and will see more than usual traffic, a skim coat is sometimes added. Other than that, it's not needed.
__________________
Davy

www.davystephenstile.com
Davy is online now   Reply With Quote
Unread 10-17-2020, 07:10 PM   #5
SC2020
Registered User
 
Join Date: Oct 2020
Posts: 11
Thumbs up

Thanks for the information Davy! This forum is great, such a good resource for help with these issues!
__________________
SC
SC2020 is offline   Reply With Quote
Unread 10-17-2020, 09:15 PM   #6
jadnashua
Veteran DIYer- Schluterville Graduate

STAR Senior Contributor

 
Join Date: Jul 2004
Location: Nashua, NH
Posts: 14,124
Vacuum up what's loose, then see what you have.

Cement doesn't cure by drying, it incorporates that water into its chemical structure...if it dries out prior to curing, that can be a problem which is why covering it, especially as we get into winter when the usual interior humidity levels drop, or if you live in a desert already, covering cement until it cures becomes more important.
__________________
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 10-18-2020, 09:58 AM   #7
SC2020
Registered User
 
Join Date: Oct 2020
Posts: 11
Thank you again to all for your input, most definitely helpful. So unless I’m missing something I’m not seeing any major red flags to prevent moving forward? The floor is not cracked or crumbling with huge divots, it is solid to stand on with some top layer sand flaking off when you rub the surface. In hindsight I guess the “sandiness” would make sense considering at a 5:1 ratio it is more than 80% sand. Again, I’ve never prepped and set a shower base before so I may just be overly concerned.

My next dilemma/question is which do I tile first, the shower walls or floor? I’ve seen many arguments for either side but I’d like some feedback for myself if possible. I’ve heard leave the bottom course of tiles off and do the walls first then go back install the floor and finish the first course. If I go this route should I skim coat the bed with thin set first because there will be traffic (me) going back and forth over the bed while I tile the walls? Or I’ve also heard just install the floor and protect it while you tile the walls, start at the bottom and work my way up from the floor? Again, any help/information is appreciated!
__________________
SC
SC2020 is offline   Reply With Quote
Unread 10-18-2020, 02:43 PM   #8
jadnashua
Veteran DIYer- Schluterville Graduate

STAR Senior Contributor

 
Join Date: Jul 2004
Location: Nashua, NH
Posts: 14,124
Some find it easier to make a clean joint if they allow the pan's tile to end underneath the bottom row, but it is not a requirement. Industry requires any changes of plane or materials to have a movement accomodation joint. That could be a gap, not a good thing in a shower, a resilient material like a caulk, or an engineered joint called a profile in the industry. An actual gap and a profile are considered a lifetime solution...caulk will often require removal and replacement over time.

So, it depends! Schluter has a profile that would make hiding any cuts on the floor at the edges that would make it much easier to keep that looking like a straight line. https://youtu.be/ks4UNPzCVNw https://youtu.be/L9tVlqVih7Q

If you do tile the pan first, you need to protect it from getting thinset and later grout on it while you handle the walls. The same is true for the pan, and I'd use a sheet of plywood or maybe a sheet of drywall (that will likely bend and follow the slope) to protect it while doing the walls.
__________________
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 10-18-2020, 06:46 PM   #9
Tool Guy - Kg
Moderator -- Wisconsin Kitchen & Bath Remodeler
 
Tool Guy - Kg's Avatar
 
Join Date: Feb 2005
Location: Oak Creek, WI
Posts: 22,157
I’m the type that does the walls first, leaving out the bottom row until after the pan is done. I like this because it’s too easy to protect floor tile from damage when it’s not installed yet...and I like that clean joint Jim mentioned.

__________________
Tonto Goldstein... but my friends call me Bubba

Help an awesome summer camp!
Tool Guy - Kg is offline   Reply With Quote
Unread 10-19-2020, 05:18 PM   #10
SC2020
Registered User
 
Join Date: Oct 2020
Posts: 11
Thanks for the suggestions Jim and Bubba, that’s most likely the direction I will go!
__________________
SC
SC2020 is offline   Reply With Quote
Unread 10-19-2020, 05:34 PM   #11
SC2020
Registered User
 
Join Date: Oct 2020
Posts: 11
Which Trowel For Shower Wall Tile?

Hi,
I’ll be tiling shower walls with 4” x 10” subway tiles over CB. My question is which trowel size/style is best for this application? I have a 1/4 x 1/4 x 1/4 square notch and a 3/16” V notch. Will either of these be sufficient with back buttering? I’ve read that wet areas require 95% minimum coverage. Any advice is much appreciated!
__________________
SC
SC2020 is offline   Reply With Quote
Unread 10-19-2020, 06:25 PM   #12
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 91,233
SC, please keep all your project questions on one thread so folks can see what you're working on and what's been previously asked and answered. A moderator can give it a more generic title any time you'd like to suggest one.

The object is to get the required coverage on the back of the tile at a final thickness of at least 3/32nds of an inch. How you get there is a matter of your mortar, your trowel, and your technique. In your current application I'd recommend you start with the 1/4" square notch and see what you can do. If necessary, adjust your mix, your trowel, or your technique. That vee notch will not give you what you need.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is online now   Reply With Quote
Unread 10-19-2020, 07:27 PM   #13
Tool Guy - Kg
Moderator -- Wisconsin Kitchen & Bath Remodeler
 
Tool Guy - Kg's Avatar
 
Join Date: Feb 2005
Location: Oak Creek, WI
Posts: 22,157
Have you chosen a mortar? I ask because a good non-sag mortar (mixed per directions and not by “eye”) goes a long way in tiling a wall with less stress.

__________________
Tonto Goldstein... but my friends call me Bubba

Help an awesome summer camp!
Tool Guy - Kg is offline   Reply With Quote
Unread 10-20-2020, 05:28 PM   #14
Davy
Moderator -- Mud Man
 
Davy's Avatar
 
Join Date: Jan 2003
Location: Princeton,Tx.- Dallas area
Posts: 32,884
I'd use the 1/4x 1/4 trowel for that size tiles. What Bubba said about non sag thinset. Custom's Prolite from Home Depot is hard to beat.
__________________
Davy

www.davystephenstile.com
Davy is online now   Reply With Quote
Unread 10-20-2020, 06:00 PM   #15
SC2020
Registered User
 
Join Date: Oct 2020
Posts: 11
Again, many thanks to all. This forum is such a help!
__________________
SC
SC2020 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
Grout looks like it's flaking frankcougar Tile Forum/Advice Board 2 04-11-2014 08:20 AM
Flaking Slate? Bkahuna Tile Forum/Advice Board 2 04-15-2009 09:14 PM
Help - Slate is flaking away... Nicole123 Tile Forum/Advice Board 6 07-09-2008 08:57 AM
flaking grout bigcaat Cleaning, Restoration and Sealing 3 04-29-2008 04:04 PM
Flaking Slate Nitz Cleaning, Restoration and Sealing 2 04-19-2006 04:04 PM


All times are GMT -6. The time now is 11:17 AM.


Sponsors

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