Kerdi shower system, a do it yourself project?

[Richard]

Wife & I are nearing the end of a project.... gutted a space to make it a full bath. Hired out a plumber to do the plumbing, I framed in the shower. We set the floor tile & all plumbing fixtures.

Today the bathroom is done except for the shower itself.

Roughly 4 1/2' x 4'.

I've read about the Kerdi system... am wondering if it's straight forward enough for a (decently experienced) DIY'er.

We've never done this system but the wife tiled the first bathroom just fine.

I was told today that I need to install "simple" drywall over the studs? (yikes! that really threw me for a loop!)

Forgetting about the floor for a minute...

Install drywall, tape not needed then adhere the Kerdi membrane to the drywall (using corners & cutouts for handles & sprays)

Again, forgetting about floor for a moment.... do the above and if done properly, you now have a water-tight shower??!

So far, this isn't striking me as rocket science.

Now....the floor.

Here is where it might be worth hiring out. (shower is upstairs)

Current floor is 3/4" subfloor. I understand you can get a Kerdi floor or pour your own. Here's my question about the Kerdi floor.

For simple conversation, let's say my floor is 4 1/2' square. Rather than the drain be in the center of the floor, it's skewed to the side. It is 12" from the shower entrance door, so about 3 1/2" from the rear wall. It is pretty well centered side to side.

(roof comes down at a slope so the last part of the shower will bang your head if you go back there so it's a bit skewed towards the door)

Can a Kerdi floor handle an off-center drain like that?

Am I stuck doing the mortar floor? (which I'd have a pro do so the slope is correct)

 

[Richard]

Another Question...

I have a mental block about using normal drywall inside a shower. I "get it" that it will remain waterproof if the Kerdi is installed correctly....still.... I have an OCD mental block about drywall there.

Forgetting cost, would it be better if I used Durrock? I'd feel better given it's strength. I know it can suck moisture out of the glue used to adhere the Kerdi membrane.... would moistening the Durrock get around that issue?


Drywall??? my head is spinning!

 

[bamboozled]

I've never done it but I've watched it done. My dad has used Schluter Kerdi exclusively for probably 15 years now, no issues that I am aware of. I've only ever seen him do it over drywall, I know it seems strange but as long as you keep the membrane intact its fine. He does use durock on the curb tho before he wraps it with kerdi.

For the pan, he uses some kind of sand topping compound and does his slope out from the drain with a screed, covers it with kerdi after it sets. He uses a Schluter/Kerdi drain kit.

 

[prichard]

I did my last one with a mortar bed, cement board and Noble wrap (kerdi competitor). I'll never do mortar bed again. One I'm in the middle of I bought a fiberglass pan and durarock walls. I'd go with wrap if would be used much. But we'll likely only use very occasionally over then next few years then we're demoing the house.

 

[patchnball]

kerdi / schluter makes a shower curb.....use it...They also make the pre sloped floor. Takes that out of the equation. Their floors are made in different sizes. Might get lucky and the drain will line up. If not offset the pre sloped floor and fill in the side with a mud bed. Been using them for some time now. I use the green board instead of regular drywall. They now make a mildew resistant drywall that would also work. If you decide to use Durock...get the pre sloped floor pan, Durock the walls, tape and mud joints with thin set mortar. Paint with the waterproofer sold at Lowes or Home Depot set tile and grout. You can do this.

 

[Tough Luck]

We recently remodeled two showers using KBRS shower pans. KBRS Products - Shower Pan, Shower Base, Tileable, ADA, Shower, Bathroom, Ready to Tile | Showerbase.com - KBRS, Inc.
They were custom based on our dimensions. They're good, but pricey. Used standard cement board on the walls.

 

[rtimgray]

I don't understand the issue with installing a mud bed for the offset drain. I was a little apprehensive the first time I did one, but was pleasantly surprised at how easy it was.

Cost is minimal for the materials and it only takes a couple of hours for 6 x 6 shower or so. If you really mess it up, you can probably bust it up with a hammer and take it out. You might be pleased with what you accomplish.

While slope is (of course) important, it's pretty easy to do. Mark your level line on the wall and set your drain below that. I use straight pieces of 1 x 3 lumber as screeds (longer for corners and shorter for sides). Just pour it, screed it, float it - done.

Whatever you choose, I hope it works out well for you. There are a lot of crafts where the complexity of it is an illusion, and most of the work can be accomplished by a handyman (or woman).

Good luck and take care.

 

[Raised on a Deere]

Wife & I are nearing the end of a project.... gutted a space to make it a full bath. Hired out a plumber to do the plumbing, I framed in the shower. We set the floor tile & all plumbing fixtures.

Today the bathroom is done except for the shower itself.

Roughly 4 1/2' x 4'.

I've read about the Kerdi system... am wondering if it's straight forward enough for a (decently experienced) DIY'er.

We've never done this system but the wife tiled the first bathroom just fine.

I was told today that I need to install "simple" drywall over the studs? (yikes! that really threw me for a loop!)

Forgetting about the floor for a minute...

Install drywall, tape not needed then adhere the Kerdi membrane to the drywall (using corners & cutouts for handles & sprays)

Again, forgetting about floor for a moment.... do the above and if done properly, you now have a water-tight shower??!

So far, this isn't striking me as rocket science.

Now....the floor.

Here is where it might be worth hiring out. (shower is upstairs)

Current floor is 3/4" subfloor. I understand you can get a Kerdi floor or pour your own. Here's my question about the Kerdi floor.

For simple conversation, let's say my floor is 4 1/2' square. Rather than the drain be in the center of the floor, it's skewed to the side. It is 12" from the shower entrance door, so about 3 1/2" from the rear wall. It is pretty well centered side to side.

(roof comes down at a slope so the last part of the shower will bang your head if you go back there so it's a bit skewed towards the door)

Can a Kerdi floor handle an off-center drain like that?

Am I stuck doing the mortar floor? (which I'd have a pro do so the slope is correct)

I just did a fairly complicated corner shower stall, curb with 45 degree angles, stub walls to attach shower glass etc, and I am definitely a do it yourselfer not experienced at this sort of thing. I got the ideal I could tile because of some floor projects that turned out to be very gratifying. I avoided the short cuts so many are tempted to do and got some floors that looked better than I could have afforded to pay for.

But the shower was more of a project than I wanted it to be, and the main reason is that there are so many ways to mess it up. I could do another one like a breeze but getting my mind straight in figuring out about the modified, vs modified thinset, the pros and cons of concrete backer board, how to meet corners and lap joints and still keep a flat enough surface for tiling all turned into time consuming things to deal with as I moved along.

I used concrete backer board, and yes you can wet it and let it soak a bit before applying the membrane and no problems with the thinset curing so it will hold. My drain was off center so I poured a mud bed and used the kerdi drain kit. Figuring out about the floor mud for the pan brought come confusing reading but I actually got it done and shaped very well, just had to think it through, and plan my moves for maintaining shape. If you do not keep the mix dry enough it simply will not maintain the slope you work so hard to build. As you work packing one portion to the proper slope the disturbance will cause the other portions to move down hill away from the wall creating a swag. If you get it dry enough to hold slope then you have to absolutely make sure you packed every square inch by tamping it with your screed tool. Easy to do if you have the experience, but first time learner is probably going to be having to spend a lot of time researching to make sure they understand what is going on.

I created a bit of a mess for myself in applying the membrane. I some how got it in my head I could wrap the membrane around the vertical corner about two or three inches and then lap the other wall over that. I would not advise doing that. I would use butt seems everywhere and use the kerdi band to seal the seams. The combination of overlapping seams and wrapping a inside or outside corner just is not wise unless you are expert at getting the right amount of thinset under the membrane and have a mix thin enough to be able to squeegee the excess thinset out. Even then it is going to create a bump that if is is in the wrong place can be a headache. Around a corner it is just about impossible unless the thinset is very soupy and the corner is perfectly straight. My wall had a bit of a otherwise not noticeable bow. I had high spots that I had to apply every tile setting trick imaginable to make it come out where as if I had simply butted every seem and used the kerdi band things would have gone much faster.

If I ever do another one I would not be afraid of using drywall. One mess I had to deal with using the hardie backer board is that the 1/2" stuff was actually about .4 inches so the thickness did not match. I had expected to just but the concrete board up to my drywall and tape the joint but the thicknesses did not match so I had to modify my build to have the junction behind some other design feature. Time consuming to the nth degree for a first timer. Some people love this kind of stuff, and I like problem solving pretty much but then this bath room took over my life for too long. The niches etc just took a lot of time. But it looks great already and in a few days I will be grouting.

Have fun.

My recommendation: use the drywall assuming you have the proper studding, and butt joint the membrane in all situations except wherever it might not matter with a thickness variation. The floor is another whole story. What ever you do follow a consistent scheme. I first was going to use kerdi membrane for walls and have a shower floor using the vinyl membrane between the to layers of mud used in those systems, since I was not clear about how the offset drain was going to work out for keeping all the edges at the same height. Iit would have worked but this is not a matter of buying some material and slapping it together like building a dog house or something. You know that I am sure but perhaps something I have said will help in deciding how much tolerance you want to bring to the table for working our situations as you go along. It will be a somewhat uphill learning experience if you want this thing to be trouble free and something you are happy to look at.

 

[Cord]

Kerdi has had some pretty good marketing and I've never used their system... but I'm not a big fan of it. They use thinset for a adhesive and thinset uses a sand in the mix. This sand results in a porosity - the thinset is not water proof. I've seen a bunch of installations that show the Kerdi material laps being made so there is a exposed edge facing up. This means that water will hit that edge and will want to go behind the material. With the porous thinset you now have a leak. If the material was lapped correctly, this wouldn't be such a problem, but the instructions don't require this. Instead they rely on the thinset for the waterproofing. Not good enough in my book. Thankfully, I found something better... and it's cheaper... and easier!

Google
Tile Waterproof Membrane - Waterproof Tile Shower - Under Tile Waterproofing - Ceramic Tile Waterproofing

Fluid membrane. This stuff is like a liquid rubber product. Laticrete is but only one brand, there are dozens of comparable products out there. You only need a one gallon jug to do the average size shower. Basically, you put the cement board up (NOT drywall!!!) and reinforce the joints using mesh and thinset. Then roll the product on using a brush for the corners. It takes two coats. Water soluble and no fumes. An amature can easily do the average shower in an hour and $50 where as the Kerdi system is $300 and takes several hours. Plus the two-way and three-way corners that are so difficult to seal have the perfect waterproofing layer (see the photos of my shower shelf). I used this system on my last shower and it's the only product that I'm using from now on.

As I mentioned above, do not use drywall in the shower. It doesn't have enough stiffness to support the tile. Use a cement board product instead. Also, the bathroom should use a green board drywall which has a little more mold resistance than regular wall board. Also, don't lap the cement board over the shower flange. Butt the board to the flange and then fill the gap with thinset. This will keep the tile from tipping in at the joint.

I agree that a mud set shower is the best shower base, but you can use a shower pan if you want something a little simpler (but more expensive). Personally, I like shower pans because they are warmer on the feet. If you use a pan, be sure to bed it in some mortar. The mortar provides full support under the pan creating an incredibly solid floor and also allows you to perfectly level the pan so it drains properly.

While we are on the topic of techniques, be sure to "back butter" your tile. If you've ever seen tile that just pops off the surface, that's because it wasn't back buttered.

 

[Handloader109]

Kerdi works. Built one in 2007 when I reworked out master. As drain was not in middle of shower and the shower was odd size, I made mud floor and then 1" tile. Walls were sheet rock, yes plain. (the green is worthless if you get wet mold grows great.) tiled up with 6". Never a leak, was upstairs and sold house in 2015. I'd go for it, wasn't hard. There is a tiling site that has a lot of good info..... Good book on kerdi. Pm if you want me to find it for you.