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-   -   Kerdi shower kit in basement -- order of operations help (https://www.johnbridge.com/vbulletin/showthread.php?t=129220)

IndyGopher 05-19-2020 02:04 PM

Kerdi shower kit in basement -- order of operations help
Great forum, everyone! I'm constantly directed here from Google searches.
Finishing our basement and looking for confirmation (or correction) on the order of things when installing a Kerdi kit in a basement. If this is detailed in the book, feel free to tell me to just buy that and buzz off, lol. Thanks!

1) I've got the shower framed to exact dimensions for a 38 x 60 offset Kerdi pan, allowing for 1/2" drywall on three sides.

2) Builders left a boxed out drain. What's typically in place there at the rough-in inspection? Should I install a riser and cap it for now...or is that either too little or too much? I might call my inspector and see what he wants, but your opinions appreciated.

3) Drywall will go up after inspection.

4) After drywall, Kerdi the walls and perhaps even tile, leaving the bottom couple rows untiled to allow for placement of the pan.

5) Prepare drain. I saw a video on Youtube about working with a boxed out drain. They cut the riser to appropriate height using the dryfit pan and drain, then placed a 4" PVC coupler around that to slab height, then filled in the box around the coupler using Quikrete.

6) Set the pan using thinset.

7) Finish up tile on the walls.

8) Finish drain install (cement to the precut riser and place into thinset).

9) Tile pan.

These kits also come with a curb. At what point is that installed?

Sorry this got longer than I intended, but I appreciate any advice on what I've missed or screwed up above. First time I've attempted anything of this magnitude, but I taught myself to frame and run electrical in this 2200 sf basement, so I'm confident I can do this as well with your expert advice :-) Thanks!

cx 05-19-2020 03:34 PM

Welcome, Nick. :)

2 thru 7. You best contact your code compliance inspector before you go any further to ensure he is going to allow the Kerdi shower constructed with drywall as the backing material. He should, but you may need to show him the Schluter ICC-ER (available from the Schluter Kerdi site or in our Liberry) if he's not familiar with the product.

Customarily your first inspection is for the installed shower receptor, frequently including the flood test. To do that with the Kerdi System you need to have already completed your shower except for tile. You'll need to work something out with the code compliance people if you want to do otherwise.

I personally don't even set the drain or sloped floor (always made of deck mud) until I've completed tiling the ceiling and walls except for the bottom row of tiles. You really don't wanna be doing any work over that raw foam tray provided in the kit.

And you do understand that your floor must be absolutely flat and level prior to installing that foam tray? Even then the slope will not likely meet code requirements, but it's part of the assembly and if your compliance inspector accepts the package he accepts it all.

You cannot waterproof the shower until your curb is in place.

My opinion; worth price charged.

jadnashua 05-19-2020 03:45 PM

The first thing you need to check and correct, if needed, is that the floor where the pan is going is flat AND level. If not, you want to make it that way.

The next thing that is also quite important is to ensure that the drain riser is EXACTLY where you want it AND perfectly plumb...the drain is quite large in diameter, and anything other than a very minor error will cause the drain to not sit where it needs to on the pan. There's only a small amount of slop there.

You need to install the curb before you finish up the Kerdi, corners, and a flood test. Do perform a flood test, if for nothing else, for your end confidence. If you follow the instructions, it will not leak, but then, all it takes is a small error you didn't catch.

I'd watch some of the Schluter videos on building the shower. In such a short time, they won't be able to teach you the reason why they do things that they do, but if you follow what they say AND do, you'll be fine. The two biggest things with installing Kerdi are to ensure you've mixed your thinset properly and it's a good quality, not an economy version that ends up being mostly sand with a little cement in there, and, generously wipe down the surface with a wet sponge prior to spreading the thinset. You shouldn't have standing water, but it works best if it's damp. Well, another couple of things: until you get good at it, don't try to use a huge sheet and wrap walls to minimize joints, and clean up excess mortar before it cures. THat will minimize the chance of wicking during your flood test, and make it easier to verify things are working properly.

IndyGopher 05-20-2020 09:54 AM

Wow, I knew this forum was great, but I didn't expect awesome replies like these in under 2 hours! Thanks for those great tips. Based on those, here's some additions to my plan:

1) Contact inspector to see what he wants in place at rough-in inspection. I obviously can't complete the shower until drywall goes up, so we'll have to talk about that.

2) Will definitely use leveling compound in shower stall prior to doing anything else. I knew about this but forgot to include in my original post.

3) Will order Kerdi kit so I can use the pan and drain when placing riser to ensure it's in the perfect location.

4) Will place curb before doing any waterproofing.

5) Will do flood test for peace of mind. I've seen this in a video on the Kerdi site before, so I'll just dig that up along with other videos about the process.

Thanks again! Any other tips/critiques are welcome! I'm finishing up the electrical down there this weekend with the placement of bathroom exhaust fans. I'll then have an HVAC guy come in to do all that work. I'll then run vent and supply lines using stubs left in the ceiling by the builder. Then toilet flanges. So hopefully in the next couple weeks I'll get cracking on shower!

jadnashua 05-20-2020 01:43 PM

You may already have the fans, but if not, I'm a big fan (no pun intended) of Panasonic ones...very quiet and powerful. If I were to do this again, I'd also get one that had the built-in moisture sensor that will automatically turn it on when the humidity level rises to ensure it actually is on when needed, or, you forget to turn it off and it runs all day pushing conditioned air outside. Some might use a timer, but it may not be activated, or run too short of a time. There are some moisture sensing switches that can be retrofitted to replace a simple on/off switch, and Panasonic sells a rebranded one. Sometimes, the generic one ends up cheaper, but not always. They're nice in case someone not familiar with the operation because they will always come on once things get bad. It's better to have it in the fan since the hot air rises, but even on the wall is still useful. On this model, once it comes on, it will run for 30-minutes, or at least 30-minutes after the humidity drops to a certain point. It actually looks for condensation, not the humidity level, so a hot humid day should not cause it to turn on unless your walls are dripping wet!

IndyGopher 05-21-2020 02:15 PM

Thanks for the tip on fans, but I did already purchase some. Wish I would've posted on this forum before I started anything, but perhaps my next home project lol! I bought well-reviewed fans, but the ones you describe sound way better.

BTW, I spoke with my inspector today and he said it's fine to just install a riser out of the p-trap for the rough-in inspection at the shower. He wasn't familiar with Kerdi, but he took my word for it that the pan and drain go down last and wouldn't be in place at that time. He basically said I can take responsibility for it and show him at the final that everything is in place.

cx 05-21-2020 04:23 PM

A very unusual code compliance inspector, that. :)

jadnashua 05-21-2020 06:50 PM

When I did a shower for my mother, I sent the inspector links to the specs and test report so he could look it all up beforehand. He was fairly accommodating. It was his first Kerdi shower, too. This was maybe 7-8 years ago, and the stuff has been around for about 30-years...wonder how many were done without a permit and inspection?!

IndyGopher 05-23-2020 06:56 AM

Another question: I opened up the plastic drain box outs in my basement yesterday and see only a horizontal, capped 2" pipe left in each. I sort of expected to see traps, but I asked on Terry Love and one person answered to say that traps are usually not installed by builders and instead placed later given how precise one needs to be with drain placement. Typical?

Regarding inspector, yes, if I'm honest I don't know how knowledgeable he is. I assume there's rigorous exams to pass in order to obtain one of these jobs? I met him once when I installed a 14-50 outlet in my garage for EV charging and he seemed a little unsure on what he was looking for with regard to the breaker I protected it with, the max amps I could draw continuously from my charger, etc. And then chatting with him on the phone yesterday he seemed really quick and sure on certain questions (fireblocking and what he wanted to see in each electrical box) and less certain on others (plumbing and insulation). I ain't complaining, as he seems very nice and easy to work with...I was just hoping he'd be like another layer of defense against any stupid mistakes I might make!

cx 05-23-2020 11:15 AM

Yes, it's typical to simply stub up a bare riser pipe with no trap in a leave-out box when roughing-in for a poured concrete foundation slab.

Rigorous testing for code compliance inspectors? Judging from the inspectors I've dealt with over the years I'd hafta guess no. But I've never tried to get a job as an inspector.

And keep in mind that code compliance is the absolute minimum requirement in any residential construction. It gives no assurance at all about quality of work or functionality of any systems. You or your building contractor must provide that.

My opinion; worth price charged.

IndyGopher 05-25-2020 08:16 AM

Thanks again, CX. Ordered the Kerdi kit and will try to precisely place the trap and riser using the tray and drain as a guide when everything arrives! Will update this thread with progress and/or questions (more likely!) in coming weeks :-)

IndyGopher 05-28-2020 02:27 PM

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Another question for you kind folks. My Schluter kits come this weekend, so I was planning to use the materials as a template to set the traps and risers. Problem is I just took the measurements and the drain boxes I was left aren't deep enough for traps. I've only got 3 - 5" from the bottom of the plastic boxes to the center of the horizontal drain lines left in them. I tried removing the boxes, but they're firmly implanted in the concrete. Am I cutting out the bottoms and digging a few inches keeper under each? Seems a PITA to leave them at a depth that would require digging. Is that typical?

IndyGopher 06-06-2020 12:04 PM

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Bumping this again in hopes for opinions on my drain box/p-trap situation. I know this isn't a plumbing forum, so I've also posted this on Terry Love. But I know a lot of you are licensed plumbers and have a lot of experience, so I figured it's worth a shot.

Basically, in addition to post above (the tub boxes aren't deep enough for the p-traps), I received my Schluter trays this week and discovered that I also can't connect the p-traps in a position where they'll be centered and plumb through the tray. I'll post some photos to try and demonstrate, but basically if I hold the trap all the way back to where the drain pipe enters the box (the earliest possible connection point), it still sticks out past center of the Schluter drain cut-out. I'm told there's not much play with drain placement on these kits...so my questions:

1) Is the best (only?) solution to bust out some concrete upstream of the box in order to access the drain pipe earlier and make the p-trap connection in a spot that will have it centered?

2) Am I right in assuming I also need to cut out the bottom of those plastic drain boxes and possibly dig a few inches to place the traps on the same horizontal as the line coming in?

Thanks for any advice!

jadnashua 06-06-2020 07:19 PM

FWIW, the p-trap can almost fold back against itself and work just fine so that may give you a little more flexibility. People tend to think that it needs to be a linear extension of the trap arm, but that's not true.

What you're experiencing is one reason why building a pan out of deck mud is often the (cheaper) and easier way to make the pan. The tray works just fine IF the floor is flat, level, and the drain comes up where it needs to be. That's easiest in new construction, or areas where you have ready access.

To get things to fit where you need, you may need to tear up some of the floor. Also, you CAN raise the whole pan up. Schluter shows how in one of their videos, but in essence, you buy yourself some sheet of foam the required thickness, and laminate it to the floor, then install the pan on top of it. If you needed more than somewhere between an inch or an inch and a half, I wouldn't go that route, but you might be able to go a bit more. Keep in mind if you were to build a conventional shower with a preslope, liner, and setting bed, at the drain, it would be something over 2" thick, and more, if it were on a wooden subfloor, so that gives you a little flexibility and not be outside of a 'normal' shower pan. What you don't want is a huge step down out of the shower that can be dangerous with wet tile and feet.

IndyGopher 06-07-2020 04:40 PM

Thanks again, @jadnashua. Some extremely helpful advice in there once again! I hadn't considered "folding" the p-trap (obviously my first attempt at an install), but I got the same advice on another forum, along with the suggestion to combine some street 45's if needed. I'll try messing around with those angles and see what I can come up with!

jadnashua 06-07-2020 05:36 PM

Keep in mind that trying to dry fit pvc pipe and fittings usually doesn't work. The sockets are tapered and the pipe will only bottom out once you've primed and added the cement which melts the plastic. From what I've found, Schluter doesn't have much taper in their drain hub, so you probably can dry fit that, but none of the standard PVC bits. Dry fitting can leave you off by about 1/2" or more on each fitting...you need to measure carefully. Keep in mind that the stuff will continue to move for maybe as much as 20-minutes or so if it's hanging or pressure is on it. Depending on how fresh the cement is and how much you apply, the joint won't be in its final position and locked until the solvents all evaporate...depending on the conditions, and amounts involved, that can take awhile. With the taper, it can actually push the socket off of the pipe by a ways, too, unless it is held in place well by something.

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