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cx 09-24-2020 10:19 AM

1. Probably.

2. Tell us specifically what it is, but generally yes, it's probably an organic adhesive and not what you want for the application. Says somewhere on the container that it meets ANSI A136.1, yes?

3. Looks like.

4. Poke it with a screwdriver or similar tool and see if it's soft. If not, you can probably get by with it under a CBU.

5. Only if you need the extra height. If you're using Hardiebacker, read that installation instruction information you linked.

6. The only proper location for the WC drain flange is on top of the finished flooring. Whatever best accomplishes that in your situation is what I'd recommend you use. Keep in mind that the Hardiebacker 500 is not 1/2" thick. More like 7/16ths" thick.

If you can make your CBU plus thinset mortar bed plus tile plus bonding mortar thickness fit snugly under that flange you'll have what you really want.

My opinion; worth price charged.

CommanderCut 09-24-2020 02:20 PM

3 Attachment(s)
1. <...nervous laugh...>

2. Custom's SimpleSet Pre-mixed Thin-set Mortar. Exceeds A136.1 Type one.
Attachment 215464

3/4. Ummm, kinda soft... I stuck the screwdriver in as recommended and it sinks in a few mm and leaves a philips head sized mark, which you can see just adjacent to where the screwdriver is in the photo. Pushing just as hard on the clean surface doesn't leave any mark.
Attachment 215467Attachment 215466

5. 1/4" hardiebacker it is! I read somewhere that the total floor height needed to be 1-1/8" so I thought I needed the thicker hardiebacker to make up for it with the plywood subfloor measuring 3/4"

6. Got it!


cx 09-24-2020 03:51 PM

2. Not likely you could make a worse choice there, Pete. You do not want to involve yourself with anything from Homer's with a name starting with Simple. While Custom Building products makes some good tile installation materials, that is not one of them.

3/4. That's gonna be a judgement call, but your single layer subfloor is already less than I'd want for my ceramic tile installation, and an old, damaged, single layer plywood subfloor would make me even less comfortable. Yeah, it's under the terlit, but...... Entirely up to you.

5. There is no such requirement in the ceramic tile industry. There are specific requirements for subflooring called out for various industry published installation methods, and each manufacturer of tile installation substrates has his own published minimum requirements, but there is no overall thickness requirement.

My opinion; worth price charged.

CommanderCut 09-24-2020 04:18 PM

2. Understood. Will return and use non-premixed modified thinset.

3/4. I will replace the damaged subfloor.

5. Got it. Cool.

Working on fixing the plumbing today and tomorrow. Fixing subfloor water damage next.

ss3964spd 09-25-2020 07:19 AM

Pete, you'll want to replace as large a section of that compromised 3/4" ply as is practical. Meaning, you want to try to get it to span 3 joists if you can. You also want to make sure you have blocking under any unsupported edge.

Depot will have B/C grade exposure 1 plywood and that's what you want. You also want to orient the new ply so that it's long edge is perpendicular to the joists.

If you have access from below just cut out the old toilet drain. Doing so will make it easier to get the old ply out and waaaay easier to install the new ply. Added bonus is you can ensure the new flange rests atop your new tile.

CommanderCut 09-25-2020 07:31 AM

I was thinking about just replacing that entire panel, it’s not too much larger than the extent of the water damage itself.

Thanks for the advice about the plywood and how to replace it. That job is upcoming, probably Sunday or so.

No access from below unfortunately. Maybe time to purchase a reciprocating saw...??

ss3964spd 09-25-2020 07:48 AM

A rep saw will do the trick (love mine). Make sure you know there's nothing under there you could cut through, and keep the blade angle really low so you don't cut into a joist. A circular saw with the blade set to the thickness of the ply will also work in some spots.

CommanderCut 09-26-2020 01:38 AM

5 Attachment(s)
Plumbing question -
(if this is the wrong place to post this question, let me know. You all have been immensely helpful so far).

I got a new mixing valve to replace our old one that is sporadically leaking and off center from the new tub by 1/2". But there is a stud in the way and I am wondering what the best way to handle this is.

Here is a picture of the overall situation right now.

Attachment 215498Attachment 215499Attachment 215500

You can see that old valve is really close to the center stud there. That middle stud is 15.5 inches o.c. from the stud to the right.

My new valve, even when spaced over 1/2" to the right to center over the tub drain won't fit.

Attachment 215501Attachment 215502

The floor joists run along the same direction as the long edge of the bathtub, which means that this wall is perpendicular to them. So I am assuming this counts as load bearing. That middle stud (2x4) already has a 1" hole drilled into it. As the mixing valve will need to be pushed forward with that stud furred outward, I don't think I can drill another hole into it to compensate for the forward position of the mixing valve.

What do you think is the best option here?
-Add two studs, one to the left, one to the right, then remove the center stud, leaving a big stud bay in which to mount this? This would fix the problem of "old stud already has a hole that doesn't work for my setup."
-Different mixing valve? (doesn't fix the above problem)
-Something else I am not thinking of?

ss3964spd 09-26-2020 08:11 AM

No, Sir, that's not going to be a load bearing wall.

If this was mine, Pete, I'd simply demo that entire wall and rebuild it with the framing where you need it to be. Initially it appears that doing so creates more work but in the long run it could well be that it takes less time than trying to make what you have work.

Added bonus: You can clearly demonstrate to Mrs. Pete that the reciprocating saw purchase was absolutely necessary.

CommanderCut 10-03-2020 01:39 PM


You mentioned that my 3/4” plywood subfloor was “less than you would like” for laying tile.

If it does not create an uneven surface from the hallway (and it might, I’m not home at the moment) would you

1) recommend adding another 1/2” layer of plywood on top of the current subfloor?

2) Would that go underneath the tub as well or just areas where tile is going to go (up to the edge of the tub)?

cx 10-03-2020 03:19 PM

1. Yes. You currently meet the substrate manufacturer's requirement for subflooring, presuming your joists are on 16" centers, but you must remember that those recommendations are based upon testing with new material, in near perfect condition, near perfectly installed over joists with zero deflection and the test needs pass only once for the installed method to be accepted.

2. I wouldn't be concerned with under the tub, but if the tub were removed at the time I would certainly install the second layer of subflooring there, too. You'd want to pay close attention to the bottom of the profile of the front of the tub before raising the floor there and tiling to the tub.

My opinion; worth price charged.

CommanderCut 10-03-2020 05:52 PM

1 Attachment(s)
The hallway flooring sits 0.77" above the current plywood subfloor (which measures 0.73").

Attachment 215714

Adding on an additional 15/32" piece of plywood in the bathroom (actual measurement 0.47" thick) plus the hardiebacker (0.25") plus the thinset (?) and tile (5/16, but I measured it at 0.36" thick). So:

+ thinset thickness (for both the concrete board and tile)?
height of bathroom floor over current subfloor =1.08" + thinset thickness.

-0.77" height of hallway floor above current subfloor
Height of bathroom floor over hallway floor =0.31" + thinset thickness

In your experience, is this too much of a height increase going into a bathroom?

cx 10-03-2020 07:15 PM

Pete, you need to trade your dial caliper for a yardstick or steel tape or you're gonna set yourself up for disappointment come time to actually install those materials. :)

All your measurements are within the range of tolerances for the materials. The thinset mortar thickness is gonna depend upon your mortar and your trowel and your technique, but the actual industry requirement is that it be a minimum of 3/32nds" thick when the tile is fully set. You can add up all the numbers you've come up with and estimate what you might have for a step there, but until you actually install the various pieces, you're not really gonna know what you've got.

The 5/16ths" step you're predicting would be code compliant, but there are people (I would be an example) who could trip over it. Repeatedly! :D

Aside from that, and the possible aesthetic consideration of the raw tile edge, you could likely get by with your plan. Making some sort of threshold piece to match the heights might help the aesthetic part of that or you may like that even less.

My opinion; worth price charged.

CommanderCut 10-06-2020 07:00 PM

1 Attachment(s)

Pete, you need to trade your dial caliper for a yardstick or steel tape or you're gonna set yourself up for disappointment come time to actually install those materials.
Over my dead body! hahaha

I spoke with my wife and we agreed that the height difference isn't too terrible (between the hallway and the bathroom) and doing the second layer of plywood as you recommended needs to be done.

So I did some measuring with my 4' level and found the subfloor is pretty significantly crowned - highest in the middle and lowest on the edges - like a road - level along the long axis and low on the edges. Almost 1/2" lower in some places.

Attachment 215767


1) Is this 15/32" Plytanium plywood from Lowes sufficient? It is listed as "Exposure 1" and veneer grade is listed as "rated." I am not sure what that means in terms of grade.

2) Should I use a concrete floor leveling compound to level the floor or something else?

3) When do I level? Before I install the new 1/2" plywood? Or should I install the plywood and then level after that?

Houston Remodeler 10-06-2020 07:42 PM

1- No. This is sheathing and the manufacturer says it is not rated for floors. You need CC or better. ROund these parts BC is easier to find.

2- SLC = self leveling compound. If you are having height issues, the thinnest will be Liquid Backer Board by Ardex.

3- Yes, framing is always first in the line up.

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