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MLBZ521 07-24-2020 01:59 AM

Fill a sunken tub and convert to shower - Advice appreciated!
So...I've been lurking researching on this forum and others for some time now... I've found some similar threads, but I feel I should probably try and get advice for my particular situation.

We have (had) a sunken tub in our master bath and want to fill it and have a walk-in shower. I'm in the Phoenix, AZ area and it's a single level slab home. The hole to fill is roughly 61" L x 31" W x 11" D (thought he depth varies in different spots).

Currently, we're planning to do a curb-less entry and also considering a linear drain. The drain is already in the center of the floor, so it doesn't need to be moved, and I would think a longer drain in the center would give a larger "drain plain" (at least in my head it makes sense, heh).

What I've read is to:
  • backfill tub up to 4" - 6" from floor height
  • add rebar to tie into existing foundation
  • then cement the rest of the way

My concerns and questions:
  • I've read to potentially use rock and/or 3/4 minus material for the back fill as that would be easier than dirt alone. (Wouldn't need to be compacted as much?)
  • How far up should I backfill and how far from the floor level should I stop the cement? Assuming I would then build a pan on top of that, I obviously don't want the cement the same level as the floor with the plan to not have a curb. (Would how the pan is built determine this measurement?)
  • Should I build a "box" around the drain and fill that separately? (Seen this in a few things I've looked at.)

I'm attempting to take this one step at a time and thoroughly research as I go. But where I'm at, I know if I don't take in consideration my next step, that I may not end up where I want to be.

Mainly, (I think) I just need some direction on the measurements on the back fill and then I can start looking into my next step. But if I'm missing something and/or I should take something else into consideration that I haven't yet, please let me know.

Old tub/shower has been completely demoed out and is ready to be filled in pretty much. Plumbing has been moved, so that's good to go as well I believe.

Any advice or wisdom is greatly appreciated!


cx 07-24-2020 10:12 AM

Welcome, Zack. :)

Couple clarifications first. You're planning to use a direct bonded waterproofing membrane to create your shower receptor, right? And presumably on your walls, too?

By "cement," I'm guessing you mean to backfill your existing void and use concrete to complete the filling of your existing void.

I've poured many concrete foundations with a dropped area for the shower. We (customer and myself) have generally opted for a step-down entry for those, but sometimes did fill them for a zero entry set-up.

To do either of those after the fact is a bit more difficult as you don't have the option of bending your reinforcing steel to create a continuous 4" pour in the dropped area the same as the foundation field. For what I think you're trying to do, I think you could finesse the doweling and reinforcing to achieve a satisfactory floor. Less than perfect, but probably adequate.

With some sort of bonding flange drain I'd think you'd need less than 2" drop in your concrete patch to allow for a proper sloped mud bed to be placed for your shower floor. If your existing concrete is a minimum of 4" thick (fairly common requirement), you may be able to accomplish that without having to break out any more concrete around the existing opening.

As for fill, some course rock first would be OK and then your 3/4"-down base material should be fine. The base material is good not because it doesn't need compaction, but because it packs so well. I'd want to leave enough room on top to allow for a full 4 inches of concrete in the existing hole, leaving enough room on top for your sloped mud floor.

Depending upon the drain you elect to use you may be able to set your P-trap and just create enough of a leave-out above it to allow for setting your bonding flange drain. You'll want the drain in hand to determine both what you actually need for a leave-out and the actual depth below your existing concrete grade you need for your application. Not sure why you would want a linear drain if your plumbing is in the center of the shower floor, but that's up to you. A simple centered bonding flange drain would seem to be the simpler and easier choice given that location.

Fairly simple application in concept, but you may find it a little more complicated in actual accomplishment.

My opinion; worth price charged.

MLBZ521 07-24-2020 11:58 AM

2 Attachment(s)
Thanks for the reply CX.

Let me get back to you on the waterproofing plans.

Correct, yes, backfill and concrete over to fill the void. Attaching a picture of how it currently sits and what I was thinking as far as the linear drain and the slope of the floor. This is just what I was thinking, it may not be practical.

It sounds like what I was beginning to think, I need to decide on my drain and that setup before I can execute the backfill step.

cx 07-24-2020 12:37 PM

Interesting. Are the sides of that hole structural, Zack? As in as thick as the slab and reinforced, perhaps?

I'm still not seeing the advantage of a linear drain in that application.

PC7060 07-24-2020 01:32 PM


I've read to potentially use rock and/or 3/4 minus material for the back fill as that would be easier than dirt alone. (Wouldn't need to be compacted as much?)
3/4 stone (aka #57) is considered self compacting and would be preferable to using soil as the fill.

Re the linear drain, I have to agree with CX. Linear drains are typically installed to the sides of the showers. Installing in the middle would be a unnecessary expense and would look out of place (IMO).

Good luck!

jadnashua 07-24-2020 03:25 PM

Depending on how agreeable your inspector is, they tend to want a 2" minimum drop from the outside of the shower to the drain. You can do that with a curb, or the slope.

Most tubs came with a 1.5" drain line...a shower, by code, requires at least a 2" line, so you may need to double-check what you have. Many places want at least a 2" line when it's buried below the slab, so you might be okay already, but may need a new P-trap if they made that bigger on the outlet.

cx 07-24-2020 04:07 PM

Jim, when folks in the NTCA's Technical Committee looked into that 2" above the drain shower requirement, they found that the plumbing industry people and the code compliance inspection people actually believed that to apply only to the height of the top (finished top, not waterproofing layer) of the curb in a shower that had a curb. If there was no curb, they had no requirement at all. Makes absolutely no sense to me, nor did it to the other people on that committee, but that was the bottom line at the time. That's a few years back, but I've not heard of any change since then.

And we've kicked around the 2" drain line for showers here a number of times and the code does not appear to require a 2" drain line unless the actually fixtures in the shower require more than an 1 1/2" drain as best I can read the code and a shower with a single shower head would not require a larger drain.

That said, my plumber and I always installed 2" drain lines as a minimum everywhere when roughing in foundations.

MLBZ521 07-25-2020 09:54 AM

CX: Yes, I believe the hole is as thick as the slab. I think it may tapper away slightly at the bottom though (or that could just be how it broke out).

Regarding the linear drain: It wasn't solely function, but form as well. I'm currently reconsidering the drain though.

All: I'll verify the drain size regardless; I have read that and I've been meaning to check it.

Regarding the waterproofing, what would be the recommendations from your guys perspective for my application? I've seen various options in my research so far, but I'm open to suggestions and techniques.


cx 07-25-2020 11:19 AM

The only really workable option for what you've got in mind would be a direct bonded waterproofing membrane of some sort. For my money it would be only one of the sheet-type membranes.

If the sides of that depression are thick enough to be structural, adequate doweling into the sides at the proper depth to fall in the center of your new floor pour could make things a good bit easier.

I wasn't suggesting that you could not use a linear drain in that manner, only suggesting that it would add a bit of complication to the forming and tiling of your shower floor. Certainly can be made to work if that style drain is part of your aesthetic concept. Or, more importantly, Mrs. Zack's concept. :)

My opinion; worth price charged.

MLBZ521 07-25-2020 12:36 PM

That's what I was thinking, some type of sheet membrane. Do you have any suggestions that I should look at specifically?

I'll see if I can "explore" the thickness of the slab around the tub before I drill into them. If they are, about how far out would you recommend and the spacing between them? Should I do it from all four sides as well? I also have some diamond lath material that I could use as well if that would be beneficial.

I understand what you mean and I appreciate the the input on the drain (and everything else). The more information I have allows me to make a better informed decision in the end.

Lazarus 07-25-2020 01:17 PM

Schluter's "Kerdi" has been around for many years and is pretty hard to beat. There are some that might not consider it the "Gold Standard," but they are in the minority. There are quite a few good other sheet membranes out there as well. :scratch:

cx 07-25-2020 01:59 PM

1 Attachment(s)
I would be in what Laz thinks to be a minority, Zack. Schluter's Kerdi is a good and useful product and much touted on this particular forum, but there are others out there with better perm ratings and one in particular that is thinner and easier to handle in my opinion. That would be the former USG Durock Shower System membrane, no longer available from USG since they were bought out a while back. If you can still find some of that membrane, that would be my first recommendation. I'm told Contractors Direct bought a large quantity of the material before it left the market and may still have some available.

There are also a couple membranes from the Noble Company that are competitors and, again, have lower perm ratings than Kerdi. I don't personally favor them as they are somewhat stiffer, but one of them, ValueSeal, is the same thickness as Kerdi and the stiffness is something that some folks consider a positive feature.

There are other choices out there, too, but I've not personally used any of those others.

I would dowel from all four sides with #3 bars long enough to overlap in the center and have them spaced no more than 12" on center. That's the schedule I've always used in the field of my foundation slabs and I just tend to do my patches similarly. Like here if you can see it:

Attachment 214539

My opinion; worth price charged.

MLBZ521 07-25-2020 02:51 PM

CX: Are you bars continuous or overlapping? (They look continuous to me.) How far from the sides (corners) did you start? Looks roughly like six inches?

I'll look into the former USG membrane and see what I can turn up.

I was just looking more into Kerdi as yes, I see that mentioned, documented, and used often. Since I was just looking at it (and other systems may be similar or I'd have a similar question regarding them), for the Kerdi flange/drain systems, do you have to use their drain with their flange, or can you use any* (*I'll use "any" loosely here) drain with it?

cx 07-25-2020 03:13 PM

Those bars are overlapped, Zack. Just doesn't show very well in the photo. I stick them three inches or so into the concrete sides, which I've usually drilled at a slight angle, then bend them to horizontal and wire-tie them together. I just start wherever seems like the right place. That technical enough for you? :)

Always best to use the bonding flange from the same manufacturer as your membrane, but I know from experience that the Schluter and USG drains are interchangeable and I would suspect that other manufacturers' similar bonding flange drains (any that use thinset mortar as a bonding agent) would also work as well. As always, see my warranty information below.

Certainly nothing at all wrong with using Kerdi for your project, 'specially if it's more readily available to you. I'm hoping the USG membrane comes back on the market soon. We keep up with the owner of the system and he keeps telling us it will be back. If not, I'll be using Kerdi for my next shower project, too.

My opinion; worth price charged.

MLBZ521 07-25-2020 04:51 PM

Yeah, that's great info, thanks.

Regarding the drain/flange specifically: we were looking at some of those "invisible" drains (that you can lay the floor tile in), but I wasn't sure if I could use those with the Kerdi or (insert other manufacturer's) flange.

I would assume so, but better safe that sorry. I see some Kerdi "kits" (e.g. one, two) that include the flange, drain, etc. and also has a flange without the drain "kit" (e.g. one).

Ok, one more question for now I think...

Planning to use cement board for the shower walls. Should I bond the sheets with mesh tape and then cover that with a waterproof membrane (e.g. Kerdi/Noble/etc). Can I do that? Should I do that? Is that overkill? (Again, I'd rather be safe that sorry -- this entire project started because of a water leak, though it wasn't from the shower itself, so I'm being overly cautious.)

Also asking the above question to determine how much of the (insert manufactures') waterproof membrane I should be looking to purchase.

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.

cx 08-06-2020 07:35 AM

Yeah, perhaps more sleep and maybe a bit less thinking, Zack. :)

Good planning is always a useful tool, though, and you should spend as much time on that aspect as necessary. Measure twice, cut once kinda thinking.

As for your wallboard. If you're using Kerdi you can use gypsum drywall as your backing material. If you elect to use a CBU instead, I prefer the Durock over the others you listed.

As for extending beyond the wet area, if you're using CBU I would extend that beyond the wet area a few inches. I would also recommend extending the waterproofing membrane and tile outside the wet area a minimum of two inches and a little more wouldn't hurt at all. I would plan the waterproofing membrane such that the tile extends just past the edge of the membrane. The rest of the wallboard of whatever type can be finished with drywall mud whatever other finish is desired.

My opinion; worth price charged.

MLBZ521 08-13-2020 11:01 PM

Thanks Dan, CX.

Most definitely CX, trying to have all my ducks in a row so I can just start making progress and not have to take a step, wait, take a step, wait.

At this point, I'm planning to use the Kerdi membrane. I'm currently planning to revisit the plan for the backer board as well, based on the advice received so far and other research I've done.

Once I near the membrane install step, I'll setup my tile to get an idea of how far I want to carry both outside of the wet area.

Couple new questions:

How long would you recommend letting the concrete "patch" cure before building the shower pan on top?

I know the Kerdi membrane requires unmodified thinset to install (on both sides, correct? -- wall to membrane, membrane to tile). Any recommendations on what I should use that I can find at, say, my local orange store? Everything I've seen so far says "modified polymer" (I think that's what it says) on the bag.

Thanks again guys!

cx 08-14-2020 07:05 AM

If I were shopping at Homer's for my thinset mortar I'd buy white (purely appearance preference) Versabond for the entire project. Yeah, it's modified, but I know with absolute certainty that it will work just fine for all your shower applications. You don't need a Schluter warranty on accounta any failure you have with Kerdi will be an installer error, which is not covered. And if you can't see any light through holes in the membrane you'll not have any failures if you just take your time and do a workman-like installation.

When you can walk on your concrete patch without leaving a footprint you can build a deck mud shower floor on it. Waiting a few days or a couple years won't hurt it at all, though. Keep it covered with polyethylene or water until you're ready to do the shower floor, though.

My opinion; worth price charged.

MLBZ521 08-17-2020 03:11 PM

Would you recommend something else over the Versabond then? I'm not tied to the orange store by any means, that's just the closest to me, so if something was available there, great. I've seen Mapei Kerabond mentioned a lot, but not sure which I should be looking at. The local Floor & Decor has plenty of the Kerabond T (Medium-Bed and Thin-Set Tile Mortar -- what the bag label says) and only a few of the Kerabond (Tile Mortar) bags. (Admittingly, I do need to look this up to determine the different, as I haven't do that yet -- but the next question is where I've spent the last 24+ hours...)

So, I thought I was ready to start really making some (visible) progress and....then the Mrs. reminded me of something I forgot about apparently. She wanted a corner shelf/bench (for leg shaving purposes mainly).

I was planning (when I was thinking about it previously) on just a corner bench, based on the style documented in the Liberry, however... She's pretty adamant about wanting a floating shelf (i.e. it doesn't go to the floor). So...I was looking into this last night a bit and wondering if there are any recommendations that anyone had?

I've seen people DIY their own "shelfs", shelfs created out of Kerdi-board, the "GoShelf", the "Better Bench" benches/shelfs, and a few others. Any opinions on these different approaches? I was liking the idea of the "Better Bench" corner bench at the moment, but haven't been able to find any information on how install it with a membrane. It, specifically, would be drilled/mounted into the substrate (or framing behind it) and that, in itself, would puncture the waterproofing membrane, if that was applied on the wall first. So I wasn't sure how this would be handled.

What order should the bench/membrane be installed?

Drywall > membrane > bench > then membrane/tap joint the bench into the wall?

Drywall > bench > membrane over the bench and wall OR membrane around the bench and then cover and joint tap?

If there's something (a resource) worth directing me too that I haven't seen yet, please do. All I do (ok, a lot of what I do) all day is constantly repeat myself and point people to documentation I've already written -- so I'm happy to read anything that's already written that I've missed. Thanks!

cx 08-17-2020 04:07 PM

The T in Kerabond T is for thixotropic, Zack. Not sure at all how they make a non-sag mortar without some modifications to the formula and on the MAPEI website they don't even list the ANSI standard with which the mortar meets. Not at all sure what they're telling us there.

And just an FYI, there is no such thing in the ceramic tile industry as a medium-bed method of setting tiles and the term medium-bed for bonding mortars was abandoned several years ago in favor of Large and Heavy Tile mortars. MAPEI can print whatever they like on their bags, of course.

I use Custom's VersaBond for most tile applications for the same reason you would; it's the closest available source for such products. I have one flooring store in my small town who can/will order other products or I can drive 40 miles to the closest real tile store. Not worth it when I know what the VersaBond will do and have used it for many years. When I actually want an unmodified thinset mortar, usually only when doing work that might be published here, I do order DitraSet. Once again, I question whether it is actually un-modified, but that's what Bostik says it is and it's a very nice mortar to use. It's only logistics that keeps me from using it more often.

Custom also makes a non-sag version of their VersaBond, called VersaBond LFT. I've not tried it and can't testify as to its usefulness. Again, it's a LHT mortar, but nobody seems to wanna print that on the bag. Doesn't roll off the tongue as easily, I suppose. :) But the VersaBond LFT does indicate that it meets ANSI A118.4HT.

My opinion; worth price charged.

ss3964spd 08-18-2020 06:27 AM

2 Attachment(s)
Regarding the bench, Zack, I've installed the Better Benches so they have my endorsement. Of course, I've only installed a grand total of 2, in my own shower, and I'm a DIY'er, so grain/salt. ;)

Nevertheless, I'm a fan. Mine were installed against Durock foam board (similar to Schluter's product). I filled and sloped the top with Mapei 4 to 1, available from Lowes. I then covered them with Durock membrane, draped down the front, and then tied them into the foam panels with Durock membrane band and preformed inside corners. Tiled the faces but stone slabbed the tops.

Very stout. Be sure you install blocking in the walls before the drywall goes up. You'll want the finished tops to be about 16-18" above your finished floor. I had trouble getting the 4 to 1 to stay stuck to the face so went the extra mile to screw some expanded lath to the front (thanks again cx).

There are two sizes of BB, I originally bought a large and a small, but the large just took up too much space so swapped it out for another small one.

cx 08-18-2020 07:08 AM

Actually three sizes of the corner bench from Innovis (Better Bench). One is just right for the shaving step Mrs. Zack wants if you don't want a real bench in there. I've installed the two larger sizes and always do them as Dan has described, by installing them after the wall waterproofing and then waterproofing over the bench.

We can thank our old friend RobZ for that metal lath or hardware cloth on the front trick, Dan. I've used that to make the front higher to fit a particular tile pattern. :)

My opinion; worth price charged.

ss3964spd 08-18-2020 07:44 AM

3 sizes, yes, but I thought they call the smallest corner thingy a shelf, and it certainly isn't large enough for even a single cheek. ;) Would definitely work for feets though, but a small triangle of stone, and notching the tile for it, would be a heck of a lot easier.

MLBZ521 08-22-2020 10:32 PM

Thanks for the mortar info CX and thanks Dan for the Better Bench knowledge Dan. :tup2:

After my last post, I did finally find information on here regarding the Better Benches which answered most of my questions and you confirmed most of them as well, Dan. I've noticed I have better luck finding what I'm looking for when I use Google to search the forums rather than the built-in search feature...which seems common with most forums, I just always seem to forget that in the moment for some reason.

Yeah Dan, I understand what you mean. Given the space we have and what the Mrs. wants, I'm getting the "Shelf" version. If the shower was a bit deeper, we would have gone for the smaller bench, but she felt it would have come out too far and look slightly awkward. (If it turns out to be too small, I'll just order the small bench.)

I'll keep the idea for metal lath in mind if that becomes an issue for me. I have plenty of extra from a stucco wall I took down.

I've got a ton of stuff ordered, just waiting for it to come... I've seen a lot of stuff shipped to and from me via USPS that has been excessively delayed and some of my packages don't even show an estimated date any more.... So that's gonna push stuff back. But I'm doing what I can do while I wait.

That said, for the shower pan/deck mud, I see it is recommend practice to add a "slurry mix" of mortar first. Is this slurry mix anything special as far as mixing it up? Would it be recommended (or beneficial at all) to add any metal lath between the slurry and deck mud, or in the desk mud? I've seen that done here at there in some shower pans.

Regarding the deck mud itself. How do you guys "measure" your ratios? Better yet, how would you recommend that I measure mine? I'm sure guys that do this often enough can just eye ball/estimate by feel of how much they poor out of the bag and I would also assume the ratio isn't an exact science... So, if there are any tips or tricks to measuring the sand and cement outside of taking it a cup at a time... :rolleyes:

MLBZ521 08-28-2020 11:58 AM

Just a friendly bump. :)

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