Shower pre-slope discussion

weekendwarrior_2009

13 years ago

Posted by weekendwarrior_2009 (My Page) on Sun, Mar 22, 09 at 19:51

I just spent a day "discussing" the installation of a shower membrane with the guy I hired to retile my master bath. He wanted to install the shower membrane over the backboard. I won that one...it is installed behind the backerboard now. Then I did more research (checking up on him) and asked about the pre-slope and he started with the "in umpty-ump years I've been doing this..I've never" speech. He already layed in the mortar for the shower floor on the membrane and I have that sinking feeling in my stomach. Is the pre-slope a big deal and what is the potential issue for installing the membrane onto the subfloor? He told me that the mortar bed has a slope that will take care of the water. Pardon my tone, but this has been a internet, doing by the book weekend guy vs. the old school handyman kind of week. Any advice? Thank...this is a great forum. I wish I found about two weeks ago.

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RE: bathroom tile FAQ's

Posted by bill_vincent (billvincent@hotmail.com) on Mon, Mar 23, 09 at 9:38

"in umpty-ump years I've been doing this..I've never"

If he started putting it over the backerboard instead of behind it, obviously this moron has no idea of what he's doing. That would've been my cue to fire him on the spot.

Is the pre-slope a big deal and what is the potential issue for installing the membrane onto the subfloor?

Yes, it is, although not many tile installers, plumbers, or GC's realise it. There are two potential issues. First, the given that lends credibility to these issues-- tile, grout, thinset, and mortar ARE NOT WATERPROOF. This is the reason the liner goes underneath all of them.

Now, the first issue is that being that the pan membrane sits flat on the floor, there will always be water sitting in the bottom of the mud base. It needs the help of gravity for ALL the water to reach the weepholes at the base of the drain. With the water sitting there, collecting all kinds of gunk and garbage, it's the perfect breeding ground for mold, mildew, bacteria, and fungus. Is that what you want to be standing on as you get clean?

Secondly, if he set the membrane flat, I'd be willing to bet he just set the cement board in, and dropped it right to the floor, being that it's much easier than holding up an inch or so, so that it's not sitting on the bottom, but so that the mud still covers it. Why THIS would be a problem is that with standing water in the pan, the cement board will act like a straw, and wick the water into it until the water reaches the top of the membrane, where it will spill out and over, causing what appears as a leak.

This NEEDS to be addressed.

Please do me a favor, and post this discussion over on the discussions side, so more people will see it and benefit from it.

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Posted by weekendwarrior_2009 (My Page) on Mon, Mar 23, 09 at 11:44

Thanks Bill for the quick response. Please disregard my e-mail. I will let you and the other members know how this works out. It appears that just putting the fiberglass pan back would be the easiest. FYI, the walls of the shower are tiled down to about 18 inches above the floor so I am looking for the least destructive way to correct this...with a new contractor. Thanks again.

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Comments (6)

bill_vincent
13 years ago
last modified: 7 years ago
So, how're you making out?
weekendwarrior_2009
Original Author
13 years ago
last modified: 7 years ago
Bill,

I ripped out the mortar, membrane and lower ~18" of backerboard (again). I am going to re-installing the original fiberglass shower pan. My other post about the treat lumber curb is where I am now. I will cut that out down to the floor due to numerous 3 inch screws and liquid nail the previous guy used to secure the 2x4s to each other and to the subfloor and I pretty sure I don't want treated lumber in the bathroom area.

As for the rest of the bathroom, we have 1/4" backboard on the horizontal surface of the tub deck (on top of 5/8" plywood underlayment) and the vertical backsplash and front surface tiled except grout. I will post some photos on Flickr so you can see what we are doing. Oh yeah, the floor has 1/2" backerboard down and is ready for heating coils and tiling.

On the tub deck....
1. Do you put a grout or caulk line on the corners where the horizontal bull nose meets the vertical straight cut tile or overhang a bullnose piece and grout or caulk underneath?

In the shower...
1. Do you caulk the corners where the tiles meet or grout? I planned on using clear silicone in the corners but have heard that grout is just as effective.

2. When I removed the shower pan during demo, there was nothing underneath. I am now reading that one should lay mortar or foam underneath the pan. You thoughts?
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Much depends on the reason for the crack, and if the crack is active or if it's old and has stabilized. ie, no more movement. If the crack is active, it's an "all bets off" type of scenario. There's no sense in tiling over an actively moving slab. I'd need to know why it's moving. Expansive clay underneath? Water issues? Poorly compacted subsoil that has settled and thus the slab has sunken in? There are myriad reasons. Not all cracks are problematic. Large expanses of concrete can show shrinkage cracks. They are simply a part of the curing process. Shrinkage cracks will never move, they really aren't an issue. Some structural cracks are done. They've moved. They've settled. They've stabilized. They'll never move again. So not all structural cracks are an issue. It's simply actively moving cracks that you need to be wary of. SInce you've already made patch repairs to the slab, I'm guessing that the existing cracks are not active. Were they active I'd have recommended digging out the broken concrete. excavating down, filling and compacting a new base, then repouring a new slab. For your case with the cracks being inactive, I would put a crack isolation membrane down. That'll serve two purposes: 1) It'll isolate the cracked slab from your mud bed. 2) It can act as a moisture barrier, preventing moisture in the earth below the slab from wicking up through the slab and into your new mud bed. A crack isolation membrane I use is Nobel CIS. You can then put your mud base on top of the CI membrane and work up from there. I'd recommend Hydroban with that. Hydroban is a water proof barrier but not a vapor barrier, so it'll work well with the CIS which is a waterproof and vaporproof barrier. The good news? Sort of? If you use Nobel CIS (or use an equivalent product) over the entire bathroom floor slab, then you can put the sloped mud (or preformed shower tray) over the shower portion of the floor and then simply tile over the CIS on the remainder of the floor. Do understand it's not the only way. There are other products you can use. Does that make sense?
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"Also, I haven't come by the term "single source" what does that mean? " It just means that you can buy all your materials from the same place, from a "single source". A Laticrete distributor, for example. Or the same online source. "I haven't priced the cost of materials either. " The easiest way to DIY materials is to used the bagged Quikrete products. Most pans take around 2-3 bags each of Topping Mix and regular sand. The 60-80 lb bags are around $5-$8 each. Expanded metal lathe, maybe $10. The flanged drains (Laticrete and Kerdi) are indeed expensive at around $75-$100, but do realize that they save you materials and labor. You can use an inexpensive 2-part clamping drain ($5), but you'll have to read up, or research Youtube videos regarding "the divot method" of shower construction. For DIY I do think a flanged drain is much easier than the divot/clamping drain method. You'll probably have to buy a few tidbits, but you're looking at around $175-$200 max. That's an across-the-internet guesstimate. "So, I'm trying to compare cost, quality and convenience. If it's really only a small difference in cost, wouldn't the presloped laticrete with built in drain pan be easier?" Ding-ding-ding. I believe we have a winner! You can get a Laticrete pan that includes the drain, as well as a few other tidbits, for around $350. Unlike the Kerdi Tray, the Laticrete drain is already set in the pan. It even includes the curb. Personally, I think that's a pretty good deal. It is more expensive than DIYing your own mud pan, but you won't have to lug a half-dozen 80-lb bags of Quikrete, you won't have to mix your own deck mud, you won't have to calculate, layout, and then follow you drain and wall perimeter mud elevations to get the deck mud installed to the proper thickness, you won't have to screed it to the proper slope, rip your shoulder out packing the mud in place, etc, etc. Then you still have to build your own curb. The Laticrete kit includes the Laticrete curb. So the kit saves you not just a couple of days of labor, it saves you a lot of head-scratching and tinkering, too. And a helluva lot of worry wondering "am I doing it right?". It'll be pretty easy to install and more importantly, It will be right. Good luck with your project. FWIW, while there may be others too, Bill and I are both veterans, and we as well as others on this forum are more than happy to help.
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I finally finished this project and would like to share a few lessons learned, if anyone is interested: 1. Looking back, I decided to go with a deck mud shower pan instead of the preformed Laticrete one. It was pretty much a cost consideration at the time. I am a bit of a perfectionist and the biggest hangup I have with the job I did is how the shower pan turned out. I struggled getting it right and in the end, it just seems like I have too much slope in most areas and not enough in some. The preformed pan would have helped me there. Given the cost of the overall project, the extra cost for the Hydro Ban shower pan would have been nothing to even think about. 2. I spent much of my life over the last two months after work on this project and grew in appreciation for you pros who do it everyday. Not only is it a very physical job, I could never make money at it without charging crazy money. My hat's off to you folks. 3. Much appreciation is sent to the pros that give us DIYers the confidence we need to get over what would stop most. Your input is invaluable. I will attach a pic of the finished product so that Mongo can take a little credit for helping me get through this one. Thanks for the help! Jeff
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What to look for in a typical shower flood test. A typical shower built today in Vancouver or any city in North America for that matter is most likely a version of what you see above. The shower shown not one I tiled nor one that I waterproofed but a pretty good example of what you should look for and what many plumbers strive to achieve. The flood test above was at about the seven day mark. The shower’s inflatable test plug connected to the yellow extension hose was left in place for about two months and it took about 6 weeks for all the water to evaporate. This shower is in a basement and part of a rental suite in the home. We can learn some basics from studying this picture. For one the shower liner is installed with no wrinkle, no bulges or creases. But is that perfect? Had a proper periscope been installed under the liner the shower’s waterproofing liner would show signs of crinkling a bit. There was a pre-slope but not one that provided a 1/4” of drop per foot away from the drain. This is the minimum you should be searching for. Something that someone is going to need to do and something most likely not included in your budget. The inside corners on this shower where well glued and pressed tight. A good job there and I like how high the plumber brought up the membrane on the walls.The shower dam had no Outside Dam Corners and this is the huge mistake made by the plumber of this shower. Hard to blame him though since most stores in Vancouver selling the liner do not sell the outside dam corners. By the time the tile setter showed up to this shower a comedy of errors had taken place. The shower space was used as storage. I found nails, screws and all sorts of other HVAC wire and off cuts. The drywall crew used their ladders in there and screwed right through the shower dam’s rubber liner to install Denshield. Again, this is not the right way to build a shower but it is the way showers are being built all over North America. Next in was the tile guy. He gets paid to add concrete (4-1 mix or something like 3701 if the client is lucky) to the inside shower floor only and then the tile and grout. All the other work done by other people. So you have a framer for building the walls and setting the shower dam. Who’s fault is it if this shower fails? Who should be to blame? So the shower above was flood tested but the test itself only proved that the shower liner did not leak when tested. It did not prove that there was enough pre-slope but looking at the liner one can tell if you have seen enough done right prior to this one....
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bill_vincent
13 years ago
last modified: 7 years ago
On the tub deck....
1. Do you put a grout or caulk line on the corners where the horizontal bull nose meets the vertical straight cut tile or overhang a bullnose piece and grout or caulk underneath?

No, that gets caulked. I don't know why it's different with outside corners, but it is.

In the shower...
1. Do you caulk the corners where the tiles meet or grout? I planned on using clear silicone in the corners but have heard that grout is just as effective.

Caulk it, but not with silicone. Use a siliconized latex made by the same manufacturer as your grout, in the same color and texture.

2. When I removed the shower pan during demo, there was nothing underneath. I am now reading that one should lay mortar or foam underneath the pan. You thoughts?

Although it doesn't HAVE to be, it's to your benefit if it is. You won't get as much flexing out of it if it's filled.
weekendwarrior_2009
Original Author
13 years ago
last modified: 7 years ago
Bill,

I ripped out the PT curb and am awaiting a plumber to reinstall the line for the wedge-lok drain on the base of the shower pan.

I did more reading and noticed that no one has anything good to say about pre-mixed adhesive...well...you guessed it our handyman swore by the stuff and the entire shower (except recesses) and the front and backsplash of the tub deck are tiled with the TEC invision brand type adhesive. I know you can't use this stuff for a shower floor but is it okay on the shower walls? Am I am facing a back-to-square one redo?

Here is a link that might be useful: TEC Invision Website
bill_vincent
13 years ago
last modified: 7 years ago
Let me put it to you this way. It's a crap shoot. If you take it all down now, chances are good you're not only going to wreck the tile, but you're going to destroy the cement board, as well. That's about the worst that'll happen if you leave it up and it fails (which isn't certain). Guaranteed it won't have the same kind of longevity it would if it were installed with thinset, but now that it's up. I'd leave it and let the chips fall where they may. If it fails, redo it then. It won't hurt the cement board.
PRO
Avanti Tile & Stone / Stonetech
13 years ago
last modified: 7 years ago
Just thinkin' out loud here....but I think I'd probably try pulling one or two tiles off the wall and see where it goes. If it's up with mastic, it's probably still so gooey and pliable that it'll fall right off....and if the backerboard is cement, (Durock, etc)and not a fibreboard-type stuff, I don't see how pullin' a tile would damage it at all...meybe a bit messy, but certainly cleanable~~~might even be able to salvage the tiles as well, if that's an issue.

Shower pre-slope discussion

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bill_vincent

weekendwarrior_2009
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Shower pre-slope discussion

Comments (6)

bill_vincent

weekendwarrior_2009Original Author

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bill_vincent

weekendwarrior_2009Original Author

bill_vincent

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weekendwarrior_2009
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weekendwarrior_2009
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