The Kerdi Shower Book

[John Bridge]

Hi Mike, Welcome aboard.

Nope, you don't have to shingle the membrane in any particular direction. Makes no difference at all. You're thinking that water always goes down, but in thin connections like those of Kerdi, water goes in all directions including up.

And although a certain amount of moisture will wick into the joints, I have never been made aware of an actual leak. Although thin set is not waterproof indeed, the properly executed Kerdi lap joint is.

[Mike_Snyder]

Thanks John. Another Kerdi question for ya. I plan to build a ceiling tray above the steam shower's 4x6 floor. I wanted to simply frame out the tray opening with 2x4's layed flat against the ceiling and slope the opening, along the 4' length, from the 2x4's nominal 1.5" thickness and cover with drywall, taking into account for 1/2" drywall thickness, this will give me a 1" slope along the 4' length of the ceiling. My question is 1.) is this slope adequate for water runoff (1/4" per foot) along the ceiling and 2.) can I install the Kerdi on the ceiling in the same manner, using unmodified thinset? I want to tile the ceiling and am concerned about the weight of the tiles and the stregth of the Kerdi/thinset on the ceiling.

[jdm]

I believe that the recommended slope for steam-shower ceilings is 2" per foot. There also is some debate as to whether a home steam shower is typically used for long enough periods to require a sloped ceiling.

[Mike_Snyder]

Thanks Jeff. I was wondering the same thing regarding if any slope is required at all. I was planning on having a glass enclosure around two sides of the shower and would like to get a double-hinged door so I can leave the door open (inward) when the shower is not in use. This shuould allow it to dry out pretty well. The ceiling is 8' and I wanted to skip the transom, so I plan to have full glass from the curb to the ceiling and a full-height door (if possible.)

I guess I need to start a new 'bath remodel' thread as things are about to start up. I was curious about the Kerdi on the ceiling.

Thanks,
Mike

[John Bridge]

I realize I'm a little late on this one.

I wouldn't bother with a sloped ceiling in a residential shower. I don't think you're going to be in there long enough for dripping to get really serious.

I use Versa Bond to install Kerdi. I know, I know. . . Since I've been doing that I've never had any problems with Kerdi pulling loose anywere, including ceilings. If I can get my hands on some Ditra Set, I'll quit using Versa Bond on the Kerdi, but I can't unless I special order it. Ditra Set is also "Tilemate," made by Bostik.

[jdm]

Interesting that you put it that way, John.

I called my local Hydroment (Bostik) retailer who will special-order DitraSet for only $24 per bag. She told me it was virtually the same as TileMate, which is in-stock and $12 per bag.

Somehow, I don't think Herr Schlüter's logo on the bag is worth paying double.

[John Bridge]

Jeff, you would have to order Tile Mate also if you lived in Houston. Nobody I know stocks any of the Hydroment mortars. I wasn't trying to hoodwink anyone. I'm still using Versa Bond and loving it.

[jdkimes]

Does the Tile Your World book include the material found in the Kerdi Shower book?
In other words if I get the TYW book will it tell me how to install a kerdi shower?

[Mike2]

Jeff, John has a 15 page section with pictures in the TYW book covering Kerdi shower basics. The Kerdi eBook at 81 pages goes into a lot more detail.

[Site*Rite]

i John -
Great, great discussion & info related through your site. One of the most useful single sources of info I've ever come across --in any trade or subject. Experts are patient w/ newbies, members are polite and genuine in there enthusiasm for their projects, and the scope of new technology seems accessibly freindly - not shoved down your throat with ad-hype and self-promotion. Well done.

Q: I may have over looked something that would make this a silly question, but on the mud deck calc link, I notice the slope ratios value/rating seems to only apply if your drain is in the center of your pan. I know it still gives you good mixture and volume info but I was wondering if there was a formula that told you what the ideal wall to drain slope ratios would be given a certain level pre-slope volume mixture when there was varying degrees of distance from the drain to opposing walls???? More Specifically, say if you pulled a typical 60" bathtub out and converted the whole space to a rectangular shower Pan and did not move the drain??
(I get this request a lot for Condo remods in Maui)

jc
Site*Rite Handymen & Tile

[cx]

Not sure if you meant for this question to be in the Kerdi Shower Book thread, JC, but.....

I believe the deck mud calculator is gonna be averaging the thickness of the deck mud based upon the high and low extremes. If you move the drain off center in a tub-sized floor, it's not gonna make a significant difference in the volume of mud required. If you're trying to calculate your mud that closely, you're prolly spending a lot more time on calculations than you need be. It's always better to toss out a little extra mud, or make a small Yard Bunny, than come up a few pounds short by trying to be too exact.

My opinion; worth price charged.

Oh, and we always recommend moving the drain to the center on those tub conversions.

[chrisbp]

I think what JC is getting at is that in order to maintain the slope from the drain to the rear wall the mud layer would be significantly thicker over all. But in order to do this you would also have to make the slope to the front wall steeper so that the tile line is even around the perimeter.

Obviously the answer is move the drain then you don't have this problem. Otherwise some high-school math has to be put to use. But I dusted off that unused portion of my brain and did some quick calculations, it turns out there is no significant difference in the calculation methods, just use the max mud height at the wall as normal. You will however use more than twice as much mud in order to get your 1/8" to 1/4" of slope per foot to the far wall which is now 48" away from the drain instead of 24".

[John Bridge]

I actually try to mix more mud than I need, but if I come up short I'm quick enough to get a little more mixed before the original batch dries up. For a newbie I recommend over estimating. The stuff is cheap.

In Tile Your World I presented a simple process wherein you'll usually end up with a little extra. It entails figuring the amount of mud based on the thickest area of the floor, around the edges. Load the surplus into a cement bag and put it behind your neighbor's shed when he's not looking.

[Chris Flynn]

sorry to be such a computer idiot, But I have been trying to buy the Kerdi shower book and can not even find the place to buy it or download it on the tile store page.... can some one give me a clue? (Buy the way.. I am still wet behind the ears when it comes to tile... going to try a couple of projects for myself))
thanks
Chris

[davem]

Hi Chris,

Go to this page: http://www.tileyourworld.com/catalog...products_id=66
and find the "Add to Cart" button way down near the bottom. After that click "Checkout" and you're on your way.