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-   -   Fill a sunken tub and convert to shower - Advice appreciated! (https://www.johnbridge.com/vbulletin/showthread.php?t=129534)

cx 07-25-2020 06:35 PM

Zack, I believe Schluter makes a version of that tile-in drain grate (what I think you're calling the invisible drain) to go with their bonding flange drain (the one in all your links), but I'm not sure where you'd find it.

As for kits, I'd avoid them unless you see one that has only things you'll actually need for your particular installation. With Kerdi I do like to use the pre-formed corner pieces, whereas with the USG membrane I do not because the membrane is so easy to fold to make your own. The flanges for over your shower supply pipe and control valve are potentially useful only if they fit your actual application. I've never used one of either. Etc. Plan your shower and decide what you do and do not need, including the amount of membrane, and try to buy only that. I haven't shopped for Schluter materials for a long time, but others here will know who carries what.

Regardless what you use for your backer board on the shower walls you do not want to fill or tape any of the joints. The sheet waterproof membrane attached with thinset mortar will do a better job of that and it is much easier, 'specially inside corners, if the joints are open.

My opinion; worth price charged.

MLBZ521 07-25-2020 09:55 PM

Thanks again CX.

Yeah, I need to search and then ask my questions instead of the opposite way. I did find where Schluter does have the tile-in drain grate and other styles of grates in addition to the first few I found. I wonder if it's possible to smaller tiles (1", 2", or pebble/flat stones style) on their tile-in drain...

As far as kits, yes, I completely understand what you mean as that's exactly what I was thinking (piece meal could potentially be better, more cost effective, than their kits). I was also wondering if the regular membrane could be cut in strips to use as the bands (just a thought, not necessarily planning to do it).

I did fine on Schluter's website in their FAQ if you don't use their drains with their flange, it would void their warranty (if one was expecting to have that).

So you'd recommend no mesh tape, mortar, etc on the joins for the backer board? So, after installing the backer board, then apply the membrane (with mortar) -- would you do this in vertical strips still? And then use the membrane tape (e.g. kerdi-band) to seal the joints between the boards and the inside corners?

I actually do have one or two more questions, but before I ask, I'm going to search first this time. :)

cx 07-25-2020 10:13 PM

Don't fret about asking questions, Bret, that's what the site is here for.

I've never used Schluter's tile-in grate and don't know if it can accommodate smaller tiles. My guess would be yes. If you don't hear from someone here about it, call the Mother Ship and ask them. 888-472-4588 unless they've changed it recently. East coast time.

When doing Kerdi showers I definitely use the KerdiBand. While not as thin as advertised, it is thinner and somewhat more flexible than Kerdi and makes better overlaps. I try to do whole wall sections with the Kerdi membrane without overlaps and do all the joints with KerdiBand (the 5" version). In corners you can install the band first or do the walls first and then the band. Works either way. At the wall/floor joint corners I use the pre-formed corners and KerdiBand. The pre-formed corners appear to be made of the KerdiBand material.

All dealer's choice. Before KerdiBand and pre-formed corners, we folded the corners from the membrane. It works, but makes for thicker overlaps.

The USG membrane that I like so well is thinner than either the Kerdi or KerdiBand and also creases better and I make all my corners and overlaps from the membrane.

You're correct about the warranty information and it would apply to any and all manufacturer of such products. You don't really care because any problem you have with the product will be an installer error. Still best to stay with the products from a single manufacturer with those membranes if possible, though.

My opinion; worth price charged.

jadnashua 07-25-2020 11:02 PM

It would be probably tough, but doable, to use pebbles on the tile-in grate...it is covered with the Kerdi membrane, but pebbles would require it to be grouted, and that could be tough to get things solid and to look good. It would definitely be easier with a single, larger format tile that might only require a grout joint across the long side, without any along its length and maybe on the edges.

The frame for the tileable piece is basically a SS U-shaped piece with a section of Kerdi membrane bonded to the top surface. It's pretty robust so that it doesn't bend and pop off the tile you bond to it.

MLBZ521 07-26-2020 12:42 AM

Thanks guys for all wisdom so far.

I feel much more comfortable with the plans in my head right now than I did at the beginning.

I think my biggest thing before continuing is the backfill of the tub, specifically, the depth of each layer.

(Just talking out loud here...and making up pseudo numbers.). As previously mentioned, the void is roughly 11" deep. I was thinking, split the backfill in half: 4.5" of the 3/4 minus/stone and then 4.5" concrete. Which would leave me with 2" for the preslope deck mud.

Using the Shower floor deck mud calculator that I found in this post from the Liberry, the measurements and slope would checkout...

I feel like I'm coming at this kinda backwards, because I'm filling the void and also setting the drain and the placement of one directly affects the other.

I'll sleep on it and think about it again in the morning.

cx 07-26-2020 08:42 AM

Separate those steps, Zack. Do your fill and concrete patch with the final surface at the correct level and just leave out a very small section for the drain. Keep in mind that it's very easy with your deck mud to work with a depression that is too deep, but almost impossible if it's not deep enough.

The Kerdi drain requires only a 4" PVC coupling or a short piece of 4" PVC pipe (which must be removed) centered around your 2" riser pipe. That would allow you to set your drain as low as 3/4" above your new concrete grade.

Do the concrete repair first. Work on your deck mud sloped floor later.

My opinion; worth price charged.

MLBZ521 07-26-2020 01:21 PM

Oh no, I wasn't trying to do them at the same time. I just know one affects the other.

How high I raise the floor will affect how much room I have for the preslope (i.e. when attempting to do a curbless entry, I have less margin for error).

And how thick I need the preslope to be, will affect how high I need to raise the floor.

But yes, that's what I was thinking. Leaving a "deeper" depression would be better that leaving too little.

That said, is there a "maximum" thickness I would want to keep the deck mud under?

Should I put any type of barrier between the backfill and concrete? (Similar to the black material in the image you shared.)

cx 07-26-2020 02:03 PM

Let's clear up some apparent misunderstanding, Zack. If you plan to do a direct bonded waterproofing membrane shower (Kerdi or similar) you will not have a pre-slope at all. You'll make a single mud bed sloped from your bonding flange drain to the farthest corner of your shower at a minimum of 1/4" per foot. On top of that mud bed and drain and out onto your bathroom floor you will bond the membrane.

The minimum thickness under the bonding flange must be 3/4" and the thickest part will be whatever it takes for your slope. The common recommendation in the industry standards is that any mud bed thicker than 2" should be specified by a design professional. In the real world, in a confined space such as you'll have, you can make that mud bed as thick as it needs to be to accomplish your goal. You could end up much thicker and if you place the mud correctly you'll still have no problem with it at all.

When patching concrete SOG I always try to maintain the vapor retarder under the concrete as well as possible. It's never perfect, but I do try. In the photo I posted the repair was not done on one of my own slabs, but it was poured in much the same manner as my own and I made the repair in the same way. The black material is 6mil polyethylene vapor barrier material, which is acceptable in my area.

My opinion; worth price charged.

MLBZ521 07-28-2020 12:30 AM

Ah, I kept thinking I probably shouldn't be using the term "preslope" in this situation.

Thanks for the verification on the thickness of the mud bed and information on the vapor barrier, both very helpful CX.

So, my next question (and I thought I was [almost] questioned out)... :talk:

I reviewed the Deck Mud article and went by my local orange store to find what I needed. I didn't find either of the Quikrete Portland Cement nor All-Purpose Sand pictured in the article.

They did have Sakrete Portland Cement (I'd assume brand isn't an issue here? Unless it's just brand loyalty? heh), but it did have Type I-II on the packaging and wanted to verify that that isn't an issue.

For sand they had several options:
  • Quikrete Commercial Grade Corse Sand
  • Quikrete Commercial Grade Medium Sand
  • Sakrete Multi-Purpose Sand
  • Sakrete Natural Play Sand

Is there a specific one that would be more preferred?

And finally, I was also looking for what I would use as the concrete patch and the options were...somewhat overwhelming. Any recommendations on what I should (or shouldn't) be using for this?

Thanks again!

cx 07-28-2020 08:48 AM

The Type I-II Portland cement is just what you want, Zack, in whatever brand available. The only time brand matters is if the final product will be a finished surface and the color match is important. Hardly anybody will be looking at your shower mud bed, eh? :)

Never seen such a selection of bagged sands. I'd start with the Course Sand given the options, but you might hafta look in those bags to see what's really in there. The Play Sands I've used occasionally are now well graded and you have sand that's too fine for deck mud along with larger pieces that hafta be picked out of the mix. Have used both (Quikrete and Sakrete) brands and found them similar, but very different in different geographic locations. You'll just need to see what's actually in them there bags and it ain't likely to bust your budget doing so. And you can frequently find broken bags in the home centers and see right quick what usta be in the bag.

Any of the sands are gonna work for your shower floor, some might just be a lot easier to work with than others.

For your floor patch, the Quikrete Concrete Mix (#1101?) will suffice. There are a couple different versions, but you don't need anything more exotic than the original. Sakrete will have a similar product.

My opinion; worth price charged.

MLBZ521 08-01-2020 03:41 PM

Thank you again CX.

A couple more questions have popped up.

It looks like you used some type of adhesive around the perimeter of your vapor barrier for the concrete patch, if so, what should I use for this?

How do you "tie-in" cement board/hardie backer to dry wall? I would imagine I wouldn't use drywall compound like you normally would between two pieces of sheet rock. In addition to that, what if the cement board/hardie backer isn't the same thickness as the existing sheet rock? Should I extend the cement board further than I expect to carry the tile or?


cx 08-01-2020 05:29 PM

Not an adhesive, Zack, just some RedGard waterproofing membrane I had on hand to help tie the new vapor barrier material to the old. Again, not at all a perfect continuation, but it makes me feel better about it. :)

I recommend you make that junction of CBU and drywall well outside the wet area and simply treat it as another drywall joint. The CBU surface can be finished with drywall compound the same as the drywall.

Worthwhile to note that the Hardiebacker is the least good choice from that aspect as the HardieBacker 500 is not half an inch thick, but only about 7/16ths" thick, making the joint more difficult to mask. Other real CBUs (C1325 boards) are generally the full 1/2" thickness, although I think there are some that vary a bit.

My opinion; worth price charged.

jadnashua 08-01-2020 06:58 PM

Maybe the best thing on HardieBacker is that it is stronger because of the fibers in it (cellulose). That factor also makes it more troublesome to work with. It's not a bad product, just different, and you need to be aware of that if you've worked with other cement boards that are not fiber-cement products. IOW, read the instructions, then, ask questions if you have some. It can be a pain using screws anchoring it. It is easy to screw jack the panel. What I've found is that if I notice that happening, I'll run the drill in reverse while pressing down hard...that will ream out the hole, like doing a pilot hole, then you can go back forward again and get the board tight to whatever is underneath.

MLBZ521 08-06-2020 04:01 AM

Thanks for the comments guys. Been busy with work and haven't been able to reply yet, but also been doing some additional research (as well as material collection). Plan to have the backfill and concrete patch done by this weekend.

I'm looking at several options for the backer board... For reference, my shower walls are (roughly) 3ft wide x 5ft long x 8ft tall.

At the local orange store, these are the options:
  • USG Durock Cemete Board: 3ft x 5ft x 1/2in
  • Wonder Board: 3ft x 5ft x 1/2in
  • USG Durock Cemete Board: 4ft x 8ft x 1/2in
  • And the Hardiebacker which is 3' x 5' x (.25" or .42")
  • (Or drywall)

So considering my wall sizes, and CX recommended to extend the joint well outside the wet area... It makes sense to me to go with the 4' x 8' USG cement board for those walls. (+1 for extending beyond planned tile area and +1 as no cutting will be required -- I may have to trim a hair off the end so it's not sitting in the deck mud.) For my long wall, depending on what I installed first, a 5ft piece may not cover enough horizontally. Either way I go though, I'll have to make at least one cut on that wall.

Would you have any other suggestions in this scenario? Mix and match, same size for all, or?

Also, for some reason (I don't know why, but I did pull an all nighter with work this week and things are still a little fuzzy :loaded:), I've had it in my head the last couple days that I read CX's last comment as extending the waterproofing membrane outside of the wet area (not the CBU). While I have now re-read that comment...where should I end the membrane considering my bathroom is rectangle and the shower walls will butt against/linear with the rest of the wall(s). (In other words I don't have any obvious breaks/corners/etc.) And I know you said CBU can be finished just like dry wall, but I dunno if the membrane can be finished over (and it would also, I'd assume like the Hardiebacker, make it difficult to mask considering the wall would be thicker with that?) with drywall compound.

I may just be over thinking this... I need more sleep. :yawn: Heh

ss3964spd 08-06-2020 07:27 AM


I feel like you're at a point where you'll need to decide what water proofing method you want to employ, since that can determine your material selections.

If you plan to use Kerdi membrane on the walls and floor then you can forgo the CBU's altogether and just hang drywall. Or, use 1/2" Kerdi foam board for your walls and Schluter's Kerdi band to seal the seams and corners, same as if using D/W.

In any case, given that you have a 5' wide opening I assume you'll be installing glass, you don't really need to extend the wall water proofing much past the shower floor foot print. Determine where the glass will line up on the side walls, and run your water proofing and tile a couple of inches past that, or by whatever distance you feel is visually pleasing. Only other problem area is the "leg", the area at the front of the curb against the wall. You do want to water proof and tile those two areas, but again you don't need much more than 2 or 3 inches.

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