Kerdi Drain Question

[nokoni]

Hi-

I've been lurking here for quite a while, researching how to construct a custom shower. I think I have it down of what I want to do.

My plan was to build a mud base utilizing the Kerdi drain. Then, in lieu of using the Kerdi liner, I had planned on using a liquid membrane such as Hydroban or AquaDefense. Actually, it's probably going to be AquaDefense since I can't locate Hydroban in my area. Then tile on top of the liquid membrane. There's some in-between steps but that's the gist of it.

So, I went down to Home Depot today to try to special order the Kerdi drain. The plumber there told me that since I'm not using the Kerdi pre-fab styrofoam base, I shouldn't use the Kerdi drain but rather to use the drain traditionally used to build shower pans (it has a bottom flange, then another section that bolts down onto the flange, and then an adjustable screw in drain). In addition, the traditional drain is $10 while the Kerdi drain is $175 through their special order. He was actually under the impression that I was going to use the Kerdi fabric as a liner.

That didn't seem right to me since everything I've read stated that the Kerdi drain is specifically designed to seamlessly mesh with the Kerdi fabric and/or liquid membrane. I've also been following along on another website where a person is doing exactly what I want to do and he touted the ease of use of using the Kerdi drain with Hydroban.

So, I think I probably already know the answer, but isn't using the Kerdi drain with a liquid membrane going to be a better option in building a water proof shower base? Can what I want to do be achieved by using the $10 traditional shower drain? Also, can anyone point me to a distributor who sells the Kerdi line. I can't find anyone in Denver who carries it.

Thanks.

[kdev]

Hi Jason! Welcome to the forum.

A pro will be along sooner or later, but I'm pretty sure the answer is you can use either a standard clamping style drain or a Kerdi drain.

If you use a standard clamping style drain, then you have to use the 'divot' method when floating the mud for the shower base.

If you use the Kerdi drain, you do everything according to the Kerdi instructions up until the 'Install Kerdi membrane step'. Instead of installing the Kerdi membrane on the floor, you apply the liquid membrane instead.

[bbcamp]

What Kent said!

[nokoni]

I'm in the process of designing my shower and would like to have a wide ~30" shower niche. However, the wall that the niche is going into may be load bearing (double top plate; running perpendicular and down the center of the overhead attic trusses). I want to go ahead and frame out the shower niche as if the wall is load bearing.

In addition, I'd also like to install some recessed medicine cabinets across the bathroom in a 2x6 wall that may or may not be load bearing (don't think it's load bearing as previous plumbers took 4" notch out of 2x6 to fit bathtub valve for hall bathroom, well off center of overhead trusses). I believe it's 2x6 to fit the 3" vent stack for the toilet.

Can someone point me to tables/charts stating what size header I will need for the different scenarios? I'd be removing one stud for the niche and one for the medicine cabinet and the walls are second story interior walls beneath an attic.

Thanks.

[Sherry Wolf]

Silly me... What is the "divot method" of installing a traditional drain?

[ratherbefishing]

You got me looking around. This is all I found:
http://www.awc.org/pdf/wcd1-300.pdf
http://www.southernpine.com/pdf/ref207.pdf

I wish I'd had a copy of the first document a few years ago.

I suspect it's not much of an issue. If the top of the niche is lower than a door opening, there's no shortage of room. I use 2x12s for door and window headers, to avoid making cripples. Are you really just removing one stud? Will that get the niche centered? Removing one stud nets an opening of 27.5 once you install the jacks. So, between centering the opening, and getting a full 30" inside, you may be moving two and eliminating one. If you're using CBU, 16" centers isn't as critical, since the sheets aren't 4x8 anyway.

Anyway, the piece of wood is cheap, compared to the rest of the shower. I'm no engineer, but I bet a doubled 2x8 with 1/2 ply sandwich is plenty strong. 2x6 would probably do it, 2x10 if you'll sleep better.

[jwmezzanotte]

I would personaly just go with the kerdi drain.
Its maybe a bit more money, but not much in the scheme of the shower.

And it could not possibly be any easier to install.

[nokoni]

Thanks for the responses.

What's a typical price for the Kerdi drain? HD's $175 for special order seemed awfully high and I've found a couple online places selling it for $115. I can't find it locally at all.

Thanks again

[jwmezzanotte]

the kerdi drain is usually around $140.00 canadian$ in my area.

Its also nice because the drain can be adjusted slightly horizontally to match up with your tiles easier.

[jadnashua]

To bond the flange of the drain to the deckmud, you need to do two things: first, ensure that your pipe is perfectly plumb...you don't want it off by the slightest (the large diameter of the Kerdi drain will exaggerate any error); and second - to ensure it bonds to the pan, you need to make that small area 'richer' in cement so it is stickier (deck mud is not sticky, but you want the drain to be stuck in place). Some people slap a little thinset on the back, but then you have to mix two different things - easier to just take a little bit of the deckmud and add some extra cement into it and mix well. Too much, and it tends to shrink and crack, though.

[Lazarus]

Interesting. I've seen the Kerdi Drains for under a hundred bucks....

[jwmezzanotte]

Originally Posted by Lazarus

Interesting. I've seen the Kerdi Drains for under a hundred bucks....

I'm in Canada.
The land of "theres a tax on that"
Until recently we were paying almost $10 a linear foot for ditra and kerdi here. (to be fair, I'm also in a fairly isolated area) Now its a "steal" at $7.50 a linear foot.

[nokoni]

I'll be building a custom shower pan using the Kerdi drain. In preparation for this, I had a plumber take out the old drain and p-trap (full of hair and gunk) and replace it with new.

My shower is going to be 34" wide, wall to curb. The center of the old drain was located approximately 17" across this width. The new drain is approximately 19.75" across, so offset from the old location by about 2.75".

How big an issue is this? Is it worth calling the plumber and having him come back out to redo it?

Thanks.

[jadnashua]

Depends...ideally, it is perfectly centered although many are not. The difference in slopes on the short and long sides will be miniscule (1/32") if you use 1/4"/foot for the shallower slope. Depending on the tile, and how they'll fit around the drain would be the bigger inpact. I was lucky on mine, the small tile were just barely 2" square, so I was able to take four out of the middle of a sheet to go around the drain...no cutting required at all. Almost looks like I planned it! Didn't really have an idea, since the tile were purchased after the drain locatoin was set, but regardless, once in awhile, you get lucky!

[cx]

Welcome, Jason.

It'll help if your ask all your project questions on one thread so folks can see what you're working on and what's been previously asked and answered. We can change the title to something more generic any time you'd like.