What are the accepted practices for having a shower on a slab? There are designs where it’d be nice to form a drain pan as part of the slab, using the proper flanged drain, and avoid a built-up curb and liners and such. I read the code book, but my eyes are glazing over on that section, what with copper liners and hot mopping et al.
So, can a shower pan be made integral to the slab, sloped to the drain, and then stained or tiled, or is that unacceptable?
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Replies
Cloud,
I'm assuming that you are talking about doing a slab on grade house or a basement floor with a sloped shower floor finished right into the floor. Yes, you can do this, but I wouldn't. If the cement finisher is doing a large area, this might be a little taxing to ask him to get the shower floor area "perfect". In addition, if the concrete floor ever cracked, your shower is now leaking water beneath the slab because of the absence of a liner. If the idea of a curbless shower is appealing, why don't you do what we do which is to form the area where the pan will be so that the concrete in the shower area is about 1 1/2" to 2" below the rest of the concrete floor. The slab in the shower area should remain at least 4" thick by removing some of the crushed stone from the area. The new floor in the shower should have some slope so that the liner or crack isolation membrane will have pitch toward the drain. The shower area is then brought up to final height with mud to match the concrete floor in the rest of the bathroom.
carpenter in transition
Short Answer: No.
Concrete is not waterproof. Water will leak through the grout and into the slab. The slab will become wet and will start to be an excellent medium for mold growth. The shower will spread mold all over you basement and may cause alergies, coughs, headaches etc.
The membrane is not that tough, but the most important feature, which your floor is also missing is a pre-slope.
If you want easy, then buy a shower receptor, which is essentially a pre-formed base and curb which fits right onto your floor drain. Cost is a couple hundred bucks.
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
The problem with a shower receptor is that some of the locations for showers are odd-shaped spaces. These are concrete domes we're designing/building, and the curves often lead to interesting shapes and rooms. Often that creates a perfect placement for a shower, though not in a typical shape, so now I'm trying to find the easiest way to turn that into a functioning shower. I've always been fond of no-threshhold showers (some are probably for handicap/wheelchair access) I've seen in some hotels and such, and am looking for the right combo of materials and methods to create something a bit more integral than an acrylic/fg receptor.
Then the TCA says to do the following:
1. Float a Mortar Bed Pre-Slope. This could be on top of the slab, or bust out the slab and float in the cavity.
2. Install a 2 part clamping drain.
3. Add a 40 mil shower membrane, CPE or PVC. Want a European look? Take the pan membrane outside and beyond the shower enclosure 4-6 feet. No curb.
4. Float a setting bed, same slope as #1 above, 1/4" per foot. Terminate the slope a bit outside the "shower" I would consider using TCA's Handicap specs for this type of set up.
5. Tile away!Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1927
Thanks Boris and Tim...I can work with that, and appreciate your time.
I'm finally getting to the detail of the curbless shower pan assembly. If it's ok with you or anyone else, I'd like to see if the drawing captures what you describe. The parts of this I'm a bit unsure of is if the tile outside the shower enclosure should slope the same as the tile inside, and if so, how to attach the optional partition on a sloped base. I'm envisioning the partition as a walk-around wall to block some splash and maybe give some privacy, so perhaps the recess in the slab (2-2.5") should only be where the partition isn't, i.e., just cover the enclosure and the area where you walk out of the enclosure. And should any problems with cracking tiles or grout lines be expected at the edge where the shower pan ends and the original slab begins, or will that edge be completely stable?
Corrections? Suggestions? Thanks.
Your pre-slope and the membrane on top of it is at a quarter inch per foot. But as soon as you get out of the shower area, the top setting bed flattens out. Thus, at some point the pre-slope ends, which I assume is the 4 foot portion outside the pan.
The way I have seen this detailed spec'ed by architects following TCA guildelines is to treat the whole floor as one big pan, which entails sloping the whole floor or at least having the whole floor be membraned. This can be troublesome. And if you try to combine a top membrane and a pre-slope membrane, at some point they overlap or meet, and that juncture is problematic, too.
There is a product called Kerdi made by Schulter (pronounced Sh-looooter)which would be ideal. It would not be a two part clamping drain but a proprietary Kerdi Drain and the membrane goes on top of the setting bed, not in a pre-slope. These are ideal applications for Kerdi.
I would suggest you look into the Kerdi product. They are desingned for this purpose in Germany where these types of showers are prevalent.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Thanks for looking. I read a lot about Kerdi Drain today, but also saw a post, I think from you, that it wasn't code everywhere. Has this changed? I know their stuff is available from my fave tile store. Don't know about elsewhere.
Kerdi is not Code in California, BUT, and this is a big but, you can talk to your inspector and and propose this in the Application Process. The Tech folks at Schulter will provide an ANSI spec to the inspector and a perhaps a drawing. You might buy a section of the fabric and the special drain to show the inpsectors in advance.
I have repeatedly gotten these applications approved in advance; installed them, and they have passed the flood test to the delight of the inspectors. The Kerdi, by the way, goes all the way up the wall to the shower head, not just 12-15 inches, OK. So there is an added expense. If your slab has cracks, you can use Ditra (another Schulter product) as a de-coupler. I think (but I am not sure) the Kerdi goes first, then the Ditra. But I don't know, I haven't used the Schulter stuff much, only a couple times a year.
Another neat product Schulter has is Troba, which is used on exterior applications to dry out the bottom of a slab, and if you really want to bullet proof a setting bed, try putting that stuff underneath. They also have a nice line of transitions and other tile products.
But back to the inspectors, all they are really insterested in is having the pan hold water for 24 hours. Indeed, my guy hangs around only about 30 minutes.
Good Luck, and for your application I would pick Kerdi.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Cloud
I have a pic. of a basement shower. First pour and liner in place prior to the final pour.
I have it saved to cd and can't seem to downsize it to post on this site. But if you want me to e-mail it to you let me know.
Kevin
Cloud
Here's that pic.
So you poured a slab covering the area of the shower plus some amt? How far beyond the shower did you extend this slab? And put the pex into this slab? And it looks like you sloped it before the membrane? So what will happen with the final pour--will the finishers be able to give that the proper slope while also getting the rest of the floor done? The pict is interesting. Thanks a lot! Got a final picture?
Cloud
The liner and slab extended 6" beyond the shower area. We installed screeds for the finishers to work from plus the finishers are the best in the area. Yes the first pour was sloped to the drain and the heat does go under the shower, have done this on 5 previous showers and have had no problems. The shower floor is now finished it is a finished concrete floor with colour in the mix the floor was sanded one month after being poured to expose some of the aggregate and then will be sealed. The finishers have not applied the sealer yet but should any day I will post a pic. in the next few days. By the way noticing your interest in geo-thermal in other posts I should point out the radiant floor is being heated by a ground source heat pump.
Also the two outside walls in this shower are going to be concrete also. This will be a first for any of my jobs. The finishers have already done a test wall and it looks good I will let you know how it goes when they get it done, should be in the next week or so.
Edited 5/29/2002 9:11:12 PM ET by KC
Most excellent! I look forward to the finished product. A client or three thanks y'all.
Sloped concrete walk in shower
Hi Kevin would you still have these photos? I'm down in Missouri and walk in showers are kinda rare! Many thanks, Francis
You're posting to a 14 year old thread. Most of those guys are wearing diapers now.
A good thread deserves an new
A good thread deserves a new post...and old tile setter a new diaper!