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 05-23-2020, 08:39 PM   #1
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
NCKyle's mud pan shower and Ditra-Heat bathroom project

Hi all. First off, as an amateur trying to learn as much as I can, your old threads have been invaluable, so thanks for all of your unknowing help over these last few months. However, I've finally run into an issue I can't find an answer for anywhere.

I'm building a mud shower pan on a plywood subfloor in my master bath, and am at the phase where I have the tar paper/metal mesh down, and am prepping for the preslope. My confusion lies with getting the required mud thickness at the drain.

The shower drain my plumber installed is directly on top of the subfloor. The drain has 3 pieces:
1. The bottom piece (screwed into the subfloor)
2. The clamping/middle piece bolted directly on top of it
3. The grate that screws in on top

The thickness of #1 and #2 are about 1/8" each. So, with #3 (grate) removed, the high point of the drain is maybe 1/4" above the subfloor.

From what I've been able to gather, you should have the thickness of your deck mud in your preslope be a minimum of 3/4" at the drain. However, I can't think of a way to accomplish this with the current drain installation - it seems like I could get a max of 1/4", and that would require putting mud over the edge of piece #1 of the drain and right up to piece #2 (BTW, quick sidebar - should that be done anyway, or should the mud stop before it covers any of piece #1?).

Anyway, tl;dr: the drain I'm staring in my subfloor at doesn't seem compatible with the need for a 3/4" preslope thickness at the drain - unless I should just be leveling the drain-surrounding mud above the level of the lower pieces of the drain, with a ~1/2" wall of preslope surrounding them, or something.

Any thoughts?

Thanks!
__________________
Kyle
NCKyle is offline   Reply With Quote
Sponsored Links
Unread 05-23-2020, 09:06 PM   #2
Davy
Moderator -- Mud Man
 
Davy's Avatar
 
Join Date: Jan 2003
Location: Princeton,Tx.- Dallas area
Posts: 32,665
Hi Kyle, welcome. We run into this all the time. The plumber should have held the bottom flange section of the drain about 3/4 up off the plywood. I usually cut the hole in the plywood so the 4 nubs on the drain bottom rests on the plywood. That usually leaves about 3/4 gap for the preslope.

Sometimes you can remove the screws and simply lift the drain up, depending on how it was plumbed and anchored from underneath. If that can't be done then it's worth cutting the drain off and starting over.
__________________
Davy

www.davystephenstile.com
Davy is offline   Reply With Quote
Unread 05-23-2020, 10:14 PM   #3
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
Ah, okay, thanks. Well, crap. I was hoping it was just me who was missing something.

I just unscrewed the drain and checked out the situation. I could lift it an inch or so without much resistance, which is the good news.

I think the main problem here may be with the hole that was cut in the subfloor for the drain. The hole was cut too wide for the nubs to sit on the floor, and there is even a tiny gap in the floor visible next to a small portion of the drain where the hole was cut slightly wider than even the outer drain flange.

I can move the drain to the side enough so that a couple of the nubs sit on the subfloor (although there is some resistance there), which gives it the right elevation. But, if I do that, I could only screw 2 of the 4 screws in - the other two screwholes would just be sitting over air.

Bleh.

I wonder what my options may be here, other than just ripping out the subfloor and drain. Is there an acceptable way to shim up portions of the drain using one-bys, or anything like that?

The only thing I can think of is putting a couple furring strips under the subfloor (running under the excessive parts of the hole), and then fixing little pieces of plywood on top of them, to give the drain nubs a surface to rest on that is level with the subfloor.
__________________
Kyle
NCKyle is offline   Reply With Quote
Unread 05-24-2020, 08:01 AM   #4
Davy
Moderator -- Mud Man
 
Davy's Avatar
 
Join Date: Jan 2003
Location: Princeton,Tx.- Dallas area
Posts: 32,665
You might can shim under the bottom flange between it and the plywood, depending how large they cut the hole. With the hole too big, it may be near impossible to get the nubs to rest on the plywood or to get the screws in it. It's good to have the screws holding the drain in place but realistically once the liner is connected to it and the top mud bed in place, the drain won't be able to come up off the floor. Still, I like screws in the drain if possible.

It's not a bad idea to check the top of the grate with a small level. Raising it like you did might tilt it out of level. But, who knows, the plumber might have set it out of level in the first place. Regardless, the top of the grate needs to be fairly level. Check it north and south and then east and west.

One way or another, you need to get 3/4 inch space under the flange for your preslope. You have lath down and you don't want the mud real thin so that it pokes the liner. Most likely, the plumber wasn't going to use tar paper and lath under the preslope. Many of them slap the mud right down on the plywood and make it real thin at the drain. Or, he might be one of those that see no need for a preslope.

The plumber I use believes in a preslope and does a pretty good job of setting the pan but he puts the preslope right on the plywood without lath. He's hard headed like most plumbers and doesn't think the lath is needed. Without lath, the preslope mud tends to bust to small pieces under the liner. It really has no place to go and pretty much stays in place. Still, I want mine to have paper and lath.
__________________
Davy

www.davystephenstile.com

Last edited by Davy; 05-24-2020 at 08:07 AM.
Davy is offline   Reply With Quote
Unread 05-24-2020, 12:00 PM   #5
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
Okay, thanks! I was trying to think if having a shim portruding above the subfloor would be bad - e.g., I wouldn't want it to be poking the liner either. But maybe I can figure something out. I appreciate the info.

Also, while I'm bothering you guys, I'm realizing I might not have the order of operations right here. Based on the tutorials I've seen, I was expecting to go in the following order:
  • Float preslope
  • Put in pan liner
  • Float curb
  • Put up and seam backer board
  • Final mud layer
  • Waterproofing w/ paintable membrane
  • Tile walls
  • Tile shower pan

But, given the recommendation I'm seeing to either tile the pan within 16 hours laying the final mud layer OR to wait 28 days, that seems impossible. How might you recommend shifting around the order of those steps?

Thanks again.
__________________
Kyle
NCKyle is offline   Reply With Quote
Unread 05-24-2020, 12:53 PM   #6
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 90,337
Welcome, Kyle.

I trust you're planning the liquid-applied direct bonded waterproofing membrane only for your walls, right?

If so, I'd recommend applying that before you place the final mud bed. And do not coat the bottom edge of your wallboard with the waterproofing membrane.

I'm not sure where folks see that timing for tiling over a dry-pack or deck mud. If you were planning to use the wet set method (you're not) you would set your tiles immediately after placing the mortar while it is still workable. But for using the thinset method (you are), the tile industry standards call for the mortar bed to cure a minimum of 20 hours but state that longer cures are desirable. It is quite common for tile setters to set shower floors the morning after placing the final mud layer the afternoon before.

You are not working with concrete, you're working with deck mud. Different animals, different handling methods.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!
cx is offline   Reply With Quote
Unread 05-24-2020, 01:50 PM   #7
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
Thanks CX! Funny, I've read so many of your posts, I feel like I'm talking to a celebrity right now.

Yep, I was only planning on Aquadefensing the walls. Just curious, why do you recommend doing that before the final bed?

That's great to hear on it being common practice to start tiling fairly quickly. As far of the source of that timing (mis?)information, here's where I was going from:

Sakrete says this on their page instructing how to use their sand mix (which I'm planning on using, + extra sand, as per the Liberry recipe) to build a shower mortar bed: Note for tiling: Tiling should begin within approximately 16 hours of the mortar bed installation. After 24 hours, the mortar bed enters a green state and should not have tile adhered to it for 28 days.

In the comments, the Sakrete rep seems to suggest the recommendation is derived from TCNA guidelines - he says: "Within the first 24 hours, green state, is the best and safest bond that you can possibly get. Outside the 24 mark, there can be risks of delamination and failure. Does this always happen, no. But it can if you do not follow the TCNA guidelines for proper mudbed and tile installation."

Maybe they are just going off of their generic concrete recommendations?
__________________
Kyle

Last edited by NCKyle; 05-24-2020 at 01:58 PM.
NCKyle is offline   Reply With Quote
Unread 05-24-2020, 01:57 PM   #8
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
As for the drain, I've now got it shimmed up to 3/4" and leveled.

I've only used a single, small shim so far, though. My thinking is that the shim should be thought of as a prop to allow the deck mud to get packed in under the rest of the flange, and that the mud is what will provide the majority of support for the drain if stepped on, etc. So, I'm trying to keep the shim minimal and give the mud as much space as I can.

Does that seem to make sense? Or am I giving the mud too much credit?
__________________
Kyle
NCKyle is offline   Reply With Quote
Unread 05-24-2020, 02:00 PM   #9
cx
Moderator emeritus
 
cx's Avatar
 
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 90,337
That should work, Kyle.

I know I've been called many things by members of this site, but celebrity is not one of them.

I would apply the wall membrane before the final mud bed just to keep from having the membrane lapping over the deck mud and also because I prefer to do everything I can in the shower prior to installing the final mud bed just to prevent damage. You must, of course, properly protect the pan liner during all the work and one of the reasons I've come to prefer using the sheet-type direct bonded waterproofing membranes for my showers. I don't even set the drain until the entire shower, except the bottom tile row on the walls, is tiled and sometimes grouted.

Now that you mention Sakrete, I do recall we've been told in past that those strange time restraints come from that manufacturer. I think they are just a bit confused on the matter. Again, you are not making concrete, you're making deck mud or dry-pack or whatever it's called in your neighborhood. Very, very different from concrete. And when properly proportioned, 'specially the water content, there is little or none of the common shrinkage problems commonly associated with placing concrete, especially in an area as small as a common shower floor.

My opinion; worth price charged.
__________________
CX

Y'ALL NEW VISITORS READ THIS HERE!

Last edited by cx; 05-24-2020 at 02:17 PM.
cx is offline   Reply With Quote
Unread 05-24-2020, 03:13 PM   #10
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
Awesome, thanks!

Assuming I'm sticking with the old school liner this time around, any recommendations for protecting the pan liner during all of the wall work? I would probably just default to padding it with moving blankets.

I guess I'd been thinking that it would be good to get the final mud bed in before getting after the walls, as I'd imagined it as being less fragile than the liner once it dried a couple days - but sounds like perhaps not?
__________________
Kyle
NCKyle is offline   Reply With Quote
Unread 05-24-2020, 06:06 PM   #11
Davy
Moderator -- Mud Man
 
Davy's Avatar
 
Join Date: Jan 2003
Location: Princeton,Tx.- Dallas area
Posts: 32,665
Once the pan liner is in, I remove the top grate and stick a few strips of duct tape over the drain. Then cover the liner with an old piece of carpet or cardboard.

My only concern is the preslope crushing around the drain when you step on it. I don't know how big the hole was cut in the plywood. Without the nubs resting on the plywood, the drain is only supported by the mud around the very outside edge of the drain. If the mud crushes and the drain falls, it's possible to pull the liner out away from the clamping flange. So, if you decide not to remove the lath and plywood, make sure the drain is supported well.

Did you notch the studs and set the blocking back so the folds in the liner won't bulge out the CBU?
__________________
Davy

www.davystephenstile.com

Last edited by Davy; 05-24-2020 at 06:20 PM.
Davy is offline   Reply With Quote
Unread 05-24-2020, 11:49 PM   #12
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
Ahh. That is a good point. I do have the one shim supporting it, but I guess, at a minimum, I should screw some more substantial pieces of wood into the bottom of the subfloor, to try to cover as much of that gap as I can. Seems like that might allow me to pack the mud in around the drain and give it direct support in the same areas as the nubs, rather than just the outer edges?

The other (non-nuclear) option would be packing in some more shims between the subfloor and drain. But I think it seems safer to absorb the force of an errant step with solid/larger boards under the gap, via mud, than to do so solely with potentially flimsy shims up top (which would also get in the way of the preslope mud in spots, etc.).

I do have the blocking set back and studs notched, thanks to the articles on here... not the prettiest chiseling job anyone's ever done, but hey.
__________________
Kyle
NCKyle is offline   Reply With Quote
Unread 05-24-2020, 11:51 PM   #13
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
Separately, one thing I'm kind of regretting was buying Hardibacker for my "cement" board. I actually emailed their CS this weekend to see what they recommend for preventing movement in the portions of the boards that overlap the pan liner (given that you can't embed them in the bed). I'm curious what the official party line is there - I assume just "the board is stiff enough that it won't move even with no fasteners for the bottom 6 inches".

I might normally be inclined to just haul them all back to HD and swap them for standard CBU, but that would be pretty difficult for me right now for COVID-related reasons. Hopefully I can make them work without regretting it in a few years.
__________________
Kyle
NCKyle is offline   Reply With Quote
Unread 05-25-2020, 01:46 AM   #14
Davy
Moderator -- Mud Man
 
Davy's Avatar
 
Join Date: Jan 2003
Location: Princeton,Tx.- Dallas area
Posts: 32,665
The main thing is that the Hardi doesn't push towards the studs if pressure is applied. You might could add a few dabs of thinset along the lower bottom of the Hardi sheets to add support. The notching doesn't have to be pretty. As long as it's enough to allow the sheets to hang down straight, it's good.

If you can get to the drain area from underneath, adding more support would be best. Deck mud (dry pack) is not concrete. It will erode and crumble if weight is applied along the edge of the mudbed. Adding wood under the drain would allow you to pack mud under there.
__________________
Davy

www.davystephenstile.com
Davy is offline   Reply With Quote
Unread 05-25-2020, 01:14 PM   #15
NCKyle
Registered User
 
Join Date: May 2020
Location: North Carolina
Posts: 15
Yeah, that makes sense. Sounds like it needs to be a balancing act with the Hardie, between creating enough of a notch to not have the liner push it out, but not so much that there's a gap for it to flex into. Supplementing with thinset sounds like a good idea, though.

Thanks again to you two for the time and expertise! It's been immensely helpful.
__________________
Kyle
NCKyle 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
Ditra Heat For Part of Project ironmanbythirty Tile Forum/Advice Board 2 11-21-2017 09:04 PM
Kitchen Project - Ditra Heat TheIcon Tile Forum/Advice Board 33 05-18-2015 07:21 AM
Ditra Heat on Shower Bench? kindacreeky Tile Forum/Advice Board 17 03-20-2015 03:05 PM
Travertine Bathroom project w/ Radiant Heat Chris885 Tile Forum/Advice Board 5 02-11-2010 12:58 PM
Bathroom Radiant Heat and Tile Project countryhouse Tile Forum/Advice Board 10 04-09-2009 09:03 AM


All times are GMT -6. The time now is 12:20 AM.


Sponsors

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