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 07-16-2014, 05:44 AM   #16
Brian blackburn
Registered User
 
Join Date: Jul 2014
Location: Katy, Texas (just west of Houston)
Posts: 16
Good comments and questions. You guys are really able to spot a lot of detail in a few lousy pictures.

The pipe in the floor at the far end of the shower is where the drain for the bathtub used to be. I trenched the floor with concrete saw and jackhammer to move the drain to the center of the shower. Then I had a vent problem, which I fixed with the pipe shown. Long story, but I am confident I have that part right. As far as the pipe exposed in the shower floor, I believe it will be fully covered by the top layer of mud, and if it isn't, there is going to be a concrete and tiled bench across that end of the shower. If any pipe is still exposed, I will notch the back of the concrete blocks as I build the bench, and then it will be completely covered.

When I installed the drain and flange and filled in the trench with concrete, the drain flange wasn't perfectly level. I had to raise the drain a hair to level it. When I did that and poured the concrete and let it set, the flange is about 1/2" too high above the rest of the floor. So when I installed the sloped sticks, I cut a bunch of little scraps of 1/2" plywood to put under the sticks. Every stick is supported on about 5-10 scraps of plywood. I glued the scraps to the floor, then glued the sticks to the scraps. That produced a perfect uniform slope all the way to the lip of the drain flange. The scraps of wood don't go right up to the edge of the flange, so about 6-8" of each stick closest to the flange is unsupported. I cut off the ends of the sticks closest to the flange so they wouldn't be in the way as I floated the floor around the flange. That's why you don't see sticks close to the flange in the pictures. But despite all the other problems, I am confident the floor has a uniform slope down to the flange. It doesn't hump up close to the flange.

Based on advice on this post, I was going to try to patch the bad spots in the prefloor and move on with the liner and main floor. I went in last night with a soft bristle brush to sweep up the broken-out parts, and as I kept sweeping, floor kept coming up. I am sure I used too little water, and parts of the floor are just dust. I have now decided to tear up the whole prefloor and start over.

I will mix it just a little wetter this time, work faster, and pack it better before screeding.

Any other advice so I can get better results the second time? I have also read about putting thinset down on the concrete slab before adding the mud. I didn't do that the first time. Is that recommended? What does that accomplish?

Thanks very much,
__________________
Brian
Brian blackburn is offline   Reply With Quote
Unread 07-16-2014, 05:59 AM   #17
jondon
Hershey Pennsylvania Tile Contractor
 
jondon's Avatar
 
Join Date: Dec 2008
Location: Annville - Pennsylvania
Posts: 6,180
Send a message via AIM to jondon
Quote:
posted by Brian:
Any other advice so I can get better results the second time? I have also read about putting thinset down on the concrete slab before adding the mud. I didn't do that the first time. Is that recommended? What does that accomplish?
Helps for the mud to bond to the concrete slab. When I go over plywood I put down tar paper and diamond lathe. This anchors the mud to the floor, same concept different substrate. If you didn't do that the first time if will make it easier to remove it cleanly
__________________

Jon Donmoyer

JD Tile

CTEF Certified Installer #825

Custom Tile Installation in Hershey & surrounding areas

Serving Dauphin, Lebanon, Berks, Chester, & Montgomery Counties PA
jondon is offline   Reply With Quote
Unread 07-18-2014, 12:21 PM   #18
Brian blackburn
Registered User
 
Join Date: Jul 2014
Location: Katy, Texas (just west of Houston)
Posts: 16
Thinset

What is the difference between modified and unmodified thinset?

I have at least 3 places I think I need to use thinset:
1. Spread over concrete slab before laying down mud for shower pan pre-slope layer.
2. With fiberglass mesh tape to seal seams and joints in hardibacker board underlayment.
3. To install porcelain floor and wall tile.

Which do I use for these tasks - modified or unmodified thinset?

Thanks,
__________________
Brian
Brian blackburn is offline   Reply With Quote
Unread 07-18-2014, 12:35 PM   #19
MAPEI - Technical Service
Company Representative
 
MAPEI - Technical Service's Avatar
 
Join Date: Jul 2013
Location: North Texas
Posts: 1,044
Unmodified thinset does not include polymers. Modified thinset includes polymers designed to give the thinset better 'grab' to both the substrate and the tile and flex slightly instead of crumbling. The 'grab' is very important when using porcelain tile that does not have much porosity. For all of the applications mentioned I would recommend a modified thinset if porcelain tile is the product being applied. Our Ultraflex 2 is a good example of a quality, modified-thinset mortar:

http://www.mapei.com/public/US/produ...2_EN_LoRes.pdf
__________________
Holden

http://www.mapei.com/US-EN/
MAPEI Product Tech Support Hotline 1-800-992-6273
MAPEI - Technical Service is offline   Reply With Quote
Unread 07-18-2014, 02:15 PM   #20
Kman
Moderator
 
Kman's Avatar
 
Join Date: Nov 2006
Location: NW Arkansas, Ozark Mountains
Posts: 12,385
Brian, please keep all question related to this project on this thread. That way anyone who wants to answer questions has the history in one place.

It's important to match the thinset to the product you're using. Check the manufacturer's recommendations for the proper thinset application. For instance, Schluter Kerdi and USG Durock membrane are similar products that function the same way, but one requires unmodified and the other requires modified.

For some cement backers, you can use the cheapest thinset you can find between the subfloor and backer. But Hardi requires a modified thinset for that application. Not sure why, but they do.
__________________
Kevin

The top ten reasons to procrastinate:

1.
Kman is offline   Reply With Quote
Unread 07-18-2014, 02:36 PM   #21
Brian blackburn
Registered User
 
Join Date: Jul 2014
Location: Katy, Texas (just west of Houston)
Posts: 16
Excellent. Thank you Dan and Kevin.
__________________
Brian
Brian blackburn is offline   Reply With Quote
Unread 07-22-2014, 11:17 AM   #22
Brian blackburn
Registered User
 
Join Date: Jul 2014
Location: Katy, Texas (just west of Houston)
Posts: 16
Backer board and mud floor

So often these days, the problem is too much information, not too little.

Two questions about cement backer board:

I read a few books, some on-line articles, and some forum posts, and I had in my mind that the general procedure is as follows:
  • Pre-slope floor
  • Liner
  • Backer boards, over top of liner (with a little gap at the floor)
  • Final mud floor layer, such that mud covers the bottom inch or more of the backer boards.
Then I saw some articles and video that said this was an absoloute no-no - the final layer of mud should not touch the backer boards.

Then I realized that I think this advice applied specifically to GP DensShield.

I am using 1/2" Hardie Backer Boards for the walls to be tiled.

Do I run the backer boards down to the liner and have the final layer of mud cover the bottom of the boards?

Second question:
I read a lot about the importance of having all the studs flat and in-line before installing the backer, which I understand. I did this the best I can, planing down a few studs in places, and adding sister studs in a couple more places. I have all the backer boards installed except the bottom row, which I won't do until at least the first layer of mud floor is finished (depending on the answer to my first question above). The backer boards all look very good and smooth - no hills or valleys at all. I think they are in good shape.

I have purchased Hydro Barrier to seal the corners and niches and to waterproof the backer board. The instructions for the Hydro Barrier say to first seal all backer board joints and corners with thinset and mesh tape, and then to put a layer of Hydro Barrier over them, imbed their fiberglass anti fracture membrane tape, and cover with another layer of HB. Lastly, the instructions say to paint the entire surface of backer boards with the HB.

How much thickness will build up on the joints when I use thinset and tape, then HB and tape? Is this enough thickness to cause problems when setting tile? How much deviation in the backer board surface can be absorbed by thinset when setting tile?
Thanks,
__________________
Brian
Brian blackburn is offline   Reply With Quote
Unread 07-22-2014, 12:12 PM   #23
Richard Tunison
Retired Tile Contractor
 
Join Date: Jul 2002
Location: Homosassa Springs, Fl
Posts: 2,689
James Hardie does not want his boards embedded in mud either. Just use regular cement board so you can embed the board as it's the only thing that secures the bottom of the boards.

Build-up is a problem with small tile and a small notch trowel. What size are your tiles?
__________________
Richard
Richard Tunison is offline   Reply With Quote
Unread 07-22-2014, 12:23 PM   #24
Richard Tunison
Retired Tile Contractor
 
Join Date: Jul 2002
Location: Homosassa Springs, Fl
Posts: 2,689
Don't forget to notch your studs and set the blocking back (or shim out the walls) to get over the liner and it's associated folds and dam corners.

A few diagrams for your viewing pleasure. Please note the dam corner and liner is not in a notch in this photo as those walls were floated with mud and did not require that treatment.
Attached Images
    
__________________
Richard
Richard Tunison is offline   Reply With Quote
Unread 07-22-2014, 02:17 PM   #25
Brian blackburn
Registered User
 
Join Date: Jul 2014
Location: Katy, Texas (just west of Houston)
Posts: 16
I think the tile will be 12 x 12, or maybe some 12 x 24.

What is "regular cement board?" Just like everything else, I can find all kinds of conflicting information in books and on-line. Some say it is ok to bury the hardie backer in floor mud, with a properly sloped floor and liner. Other sources say never to bury the board.

I have already installed all the Hardie backer all around the 4' by 8' shower, except for the bottom row. If it is ok to bury a different type of cement board in the floor mud, I could use the different board for the bottom layer.

If I use a pre-sloped floor, liner, and top layer of mud, would it be appropriate to also seal surface of the top mud layer with Redguard or Hydro Barrier?
__________________
Brian
Brian blackburn is offline   Reply With Quote
Unread 07-22-2014, 02:26 PM   #26
04Rdking
Registered User
 
Join Date: Mar 2014
Location: Celina, Texas
Posts: 389
Duroc can be, and is recommended to be, buried in the top mud bed. I believe Wonderboard can also be buried.

As far as too much information...... I suggest you pretty much stick to the information provided here and disregard all the you tube videos and such. I'm sure you've seen some of the post on here about bad tile jobs from hired "pro's".
__________________
Bill

Not a pro but avid DIYer.
Why pay when I can do it myself?
04Rdking is offline   Reply With Quote
Unread 07-22-2014, 03:10 PM   #27
Richard Tunison
Retired Tile Contractor
 
Join Date: Jul 2002
Location: Homosassa Springs, Fl
Posts: 2,689
Truth be known, some folks have no problem with embedding Hardie in the mud, including me. If you have it already, I'd use it.

Nothing on top of the final mud bed. That would negate the primary purpose of deck mud (very porous) to get water to the liner and the weep holes over your beautifully sloped, pre-slope.
__________________
Richard
Richard Tunison is offline   Reply With Quote
Unread 07-22-2014, 05:40 PM   #28
Jim Cordes
Registered User
 
Join Date: Apr 2014
Location: Pittsburgh PA
Posts: 728
The deck mud had a bit too much sand, play sand is not good for mud work, Also once you pack it down you don't want to add more unless you rough it up agian. but it is only a pre-slope..dress it up with some thin-set making sure you don't have spots that wont drain..and dont worry too much about it.

the plastic screed strips can't be used on the final bed because you all ready have proper pitch..to use them again will be too much pitch, the second layer should be uniform though out to maintain the proper 1/4 ft. drop.

I don't embed into the mud unless I am applying a bonded waterproof membrane to the surface..since you have a traditional shower you won't be using a surface membrane.
embedding promotes wicking...also be wary of a cbu that contains organic materials as it can promote mold growth..
__________________
Jim
Jim Cordes is offline   Reply With Quote
Unread 07-23-2014, 01:20 PM   #29
D123
Registered User
 
Join Date: Jul 2014
Posts: 12
Crumbly Mud

I just finished my 3rd attempt at a pre-slope which finally seems usable so I thought results from my experimenting might be helpful as I've had the same issues with sandy/crumbly surface.

IMHO....
1) a slightly richer mix of 4.5:1 (by volume) seems to be easier to work.
2) the ratio for water for a standard 5:1 dry mix is about 10(S):2(C):1(W)
3) given 1) and 2), the stability of the end result (slightly sandy but not crumbly) is mostly a direct result of a) time and b) pressure. The descriptions of "...you have about 30-45 min..." and "...really pound the mix..." are dramatic understatements. The mix needs to be dry but that also means it is drying out very quickly so a) MUST be worked very fast (which is very hard when you're learning) and b) must be compacted really well (which means laying the whole floor with a 2x4 as you can't apply enough pressure with a trowel (well, maybe the pros can...). I found it necessary to really continuously pound (and hard) the mud with the edge of an 8-in 2x4. (When near the final slope surface I switch to pounding the the 2x4 flat. It's a cycle: pound, screed, pound, add, pound, screed, pound... I only use a small trowel to spread mud.)
4) do a dry pre-mix of all the mud and then separate into buckets where you know how much water goes with each. The pros can serve it up wet all at once but I can't -- but fast wet-mixing in small batches is easier for me as long as I've pounded and screed-ed the installed batch close to perfect. Again, I had to learn to work furiously at this and I was still too slow.
5) Any remaining mud at the 'leading edge' of the work (which is drying out) I toss as I can't pound it well enough to bond.
6) By whacking/packing really well (and at a thickness that is too high) the screed removes the excess leaving only a thin bit loose (which is then re-packed with the 2x4 flat) -- whereas having to add fresh mix to packed mix requires a lot of extra pounding to get it to 'bond' (so use the freshest mud available from the mix).

As stated, IMHO ... Just thought a beginner's experiences might help explain what other beginner's have experienced.
__________________
Dave
D123 is offline   Reply With Quote
Unread 07-23-2014, 06:16 PM   #30
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 96,409
Dave, it's really not at all necessary to try to beat the mud into submission. It simply needs to be firmly packed before you carve it into shape.

I do all the packing on a shower floor with a magnesium or wood float, usually just whichever I have in my hand at the time. The effort needn't be brutal at all, just firm.

My opinion; worth price charged.
__________________
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
Need advice with existing dry pack mud floor for shower. kelerican Tile Forum/Advice Board 4 02-01-2012 06:32 AM
crack suppression membrane over dry pack shower floor wopachop Professionals' Hangout 25 07-12-2009 12:54 PM
please help... problems with dry pack mikef Tile Forum/Advice Board 6 09-26-2008 06:41 PM
dry pack shower floor w/ backer board walls jonholzer Tile Forum/Advice Board 2 11-17-2006 02:39 AM


All times are GMT -6. The time now is 10:11 AM.


Sponsors

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