Schluter Kerdi 7 Day Flood Test Results-- All Tile Guys Must See!! 

Man, idk many contractors that will invest 3 days and that much $ to test the thing they install every day. Super helpful!

I will say, your tenacity to try to learn through experimentation as well as welcoming input from an open source is very admirable and puts you well ahead of the game, imo. I have no doubt that you will indeed be able to guarantee some future client a 100% waterproof shower. Excellent job, dedication to your craft, and great video as well!

Your integrity is why you are popular and respected.

Pro contractor 33 years now, have use Schluter porducts in limited setup,was always very impressed. I have been very interested in using Kerdi for shower pans, But after watching this, I will stick to Vinyl liners. Your install is your reputation, stay with proven products. Kedri will still have place for walls etc, but not on a shower pan on my jobs. Thanks for the video

As a tile guy of 20+ years myself, I'm proud that you represent the better of my industry. Kudos!

Thanks for the level-headed response. To me, this great performance. Like you said, showers don't have standing water in them for 7 days. This one did and only had minor wetting (capillary action through the thin set and seams is my guess). It's just not an issue to me.

Great video love your posts. Schluter did a 7 day test of a 50ft deep pool and had 1.5" penetration of the 2" overlapped seams. "The wetter the better when applying the membrane." Each one of the fails had air pockets in the middle of the wet spot. These gaps pool liquid and saturate the mortar around, under, and inbetween everything.

I always use 1/2" hardibacker, unmodified thinset, kerdi, then corners, then Kerri band, then regard EVERYTHING with 2 coats on walls, 3 coats on base upto 1'. No problems. I never use drywall as a substrate. I appreciate your efforts to make us better.

Best tile channel out there , you and home renovision ! Keep it coming

This was very worthwhile for all of us in the trade. Thanks. If I had to guess I would say a small section of that K band may have been compromised by the drywall knife. I use a heavier metal trowel, in conjunction with Schluter branded trowels. However my favourite trick is to smooth kerdi and jam corners using a poly rafter square. No sharp edges, you can be quite vigourous and forceful with it.

Great video. I just did a Kerdi shower last week, and I was here partly to make sure I hadn’t done something wrong! Haha. Great channel - much love from your trades brothers & sisters in Canada 🇨🇦

7 days under water and that's all that leaked for whatever reason... I'm sold. Simple but great test. Thank you.

You did a good job on the installation. Not to mention the movement or cracking that will occur in a standard installation with people walking over the surface. I always thought the spreadable membrane that you paint over concrete board looked more promising. But I am not going to tempt my luck by tiling floors. Its a shower pan for me.

Excellent. I've been using Schluter for maybe four years now and I've decided to back it with Red Guard at the joints as a measure of insurance against fail. You just cannot go wrong with either product, altho Schluter is pricey. Red Guard alone is probably enough, but I don't want call backs. And, I'm a bit OCD. ;) Really good video, man. Thank you for taking the time to share your experience.

I never did trust using thinset to bond Kerdi membrane. Bonding a waterproof product with a non waterproof mortar was not adding up. To me using Kerdi-Fix to bond corners and band made more sense and I did do a 2 week water test. No water seepage. Great video !

I agree with you Tony. I have never considered the adhesive as a water proofing. I also use Kerdi but always go over every seam with aqua defense or some other brush/roller applied water proofing. I do what my 30 years of experience in doing tile work tells me to do even if its not what the manufacturer states. I have done many things that the Representatives say its not by the book but they have admitted to me they would trust my methods over what they have specified . Anyone who has ripped out bathrooms for 30 years knows what works and what doesn't . I am very fortunate to be working in the same homes for 30 years and I get to see what my choices of materials and methods I used have withstood the years. I will always do what I feel is best over the manufactures recommendation. Most of these companies that have long warranties are not even in business anymore since I started doing construction. So the warranty means nothing. Gluing up a waterproof material with a non modified non waterproof mortar never made any sense to me but there are guys out there that think cement board and hardibacker are waterproof also. As Isaac said , you are ultimately responsible .

Very good test and about as thorough as you're going to get. Some people need to remember that the point is to replicate the best conditions out in the field, not some hypothetical lab setting. This is a good 'stress test' and another great video idea would be to have 3 or 4 small models: one with kerdi, one with redguard/aquadefence, one with both redquard and kerdi together and one of something else. Leave them for a week or two and compare all of them together.

Not just the actual work but the video recording and editing takes time too. A lot of effort here. thanks!!!

You're very respected amongst your peers and I'm sure many of us DIY'ers as well for dedicating your time and energy to keep us well informed of new products and methods used in your trade and industry. Thank you

Great video! It was a lot of work on your part and I appreciate it.

I’m a General Contractor.. 35 years in the trades , 15 self employed and have probably..I don’t know.. 100 full-set showers (built pan) and maybe a dozen fiberglass or vikril (Kohler’s propriety material ) out there.. I’m a self taught tile pro and the evolution has been from vinyl to hot mop to just recently Kurdi products. The speed and cost savings of the Schluter products are impressive. I’ve found that it’s all about the mud and precision of the install. Big fan of the pre-sloped foam pans , kurdi nooks and Prolite thinset has given me the best results. My paranoia has me knife in some sanded urethane caulk (Vulkem116)on tough odd angle inside corners where I can’t use Kurdi corners. Especially if the stone is particularly porous and we all know that unless you call and tell a client or offer to follow up resealing the grout and stone at least every 2 years? It won’t happen and you’ll get weep down to the felt. I’ve been using miracle products and they treat me well. I’ve had one failure.. Inside neo-angle corner right under a rain head that was getting 4 + showers a day. Young couple working and going to the gym and using the shower constantly. It was over an unfinished garage and hubby had a weight bench .. laying down looking up.. Spotted a small wet spot on the subfloor inside the shower wall shoe.. That shit won’t fly so I meticulously cut out the the 2x2 porcelain floor tile and popped a 12x24 and like a surgeon.. dissected the corner. What I find? Small cut in the corner through the membrane. I smoothed the band with a 6 in taping knife (I keep my stuff razor sharp) and nicked it. That’s when the Vulkem started happening. Unless you get perfect thinset coverage, no bubbles and 2-3 inch laps AND DONT CUT THE FELT LIKE A DUMBASS ..A pass with a 1 in knife over the seam with caulk just provides a little extra measure of insurance. No issues with bond over the urethane as long as you don’t over do it. Maybe I set up a 7 day immersion with my paranoid urethane caulk and see if she weeps?

Cool test. I do think there essentially two reasonable ways to install Kerdi membrane. 1: Try and layer it like a roof with the top layers covering the bottom. I've found this is somewhat hard to do really well and leads to corners that aren't the flattest. 2: Install the corners and edges first then lay down the larger sheets. This creates much flatter corners and edges to attach the tile too.

Thanks Isaac for taking your time on that video. Would be fun to see the same test with a liquid type membrane. All the best !

Your videos saved me from making a costly mistake, thank-you!

Lesson here is don’t use a sharp corner tool to do corners, because you’ll never know if you’ve compromised the band by puncturing it. There’s many tools with burred edges that will work great and won’t snag the material

I'm an engineer so I'm approaching this a bit different. I noticed that you didn't make sure to have thin set totally covering the wall to floor seam. I also remember seeing one of your videos where you tested Kerdi corners in a cup by themselves and compared them to 2 competitors. The kerdi leaked and the others didn't. Those results make me think that the kerdi isn't waterproof itself. It becomes waterproof in conjunction with the chemicals from unmodified thin set. Would love to see a follow up video where you be sure to get good coverage of thin set in the corner between wall and floor and see how that goes. If my theory is right, no moisture.

I think you did the job way better than most would do in the field. Thanks

Ah, yes. A rebel, a disputant, a contrarian. A position I admire and understand. 👍

Those taping knifes can be pretty sharp. The seepage is happening on those seams. Could be your perferating the kerdi slightly when running the taping knife . Just seems odd why it's only happening in the corners and edges.

I do have to say that the information provided by this young man is invaluable, I have learned so much in a very short period of time. I can’t thank you enough for really wanting to take a look at your own practices. Greatly appreciate you

Very instructive , you are a good teacher, THANKS FOR THE INFO., just learning, growing and taking in as much as I can, your not afraid to show fault in your work.

That’s why you take the band to the corners then overlap the corners last . You stoped way short with the band. Just for future reference. Kerdi will not let in any moisture whatsoever when done right

The biggest problem I have with this system is that the inside corners at the bottom have three layers. I spend a lot of time getting my walls plumb. using this system at the very least you will get a quarter inch bow at the bottom which makes getting your walls plumb a waste oftime and you will have to build up your thinset like crazy to fix it as you go up

Likely a bubble in the band somewhere, my first experience with Kerdi, probably 2003ish, the rep lined a cardboard box on the shipping guy’s desk at a local tile store, sat for a week, bone dry. Been using it ever since, zero failures. No shower sees 7 days of standing water anyway, let alone 10 minutes. I do not trust laticrete, always used proflex to set, ditra set for tile, now Allset. JMO

How satisfying is to see TCNA certified tile setters at work. Hats off to you guys

Great video and insight thank you. Kerdi would NEVER do a test like this.All and all this is still a "great" product regardless. No one will EVER leave water at that level for 7 days (at least I hope not). This is why I use pressure treated wood when framing in a shower/steam shower. Just incase .Absolutelt great video Thanks much again

I watch your videos regularly to improve overall comprehension of install and tile systems. Thank you sharing your skill and knowledge in what I believe is a very efficient way. I think you are great and much respect !! Cheers

Awesome channel and great product test. I haven't used Kerdi but to me this fails for a tub but still passes for a shower stall. Keep up the great work

You did great job man, for matting and corners I don’t use adhesive, just liquid rubber and when is ready done, two or three coats on all surface.

The water penetrated at the point between the prefab corner and the kerdi band where it did not overlap 2" like the instructions say. This is a good example of why you should follow the manufacturers instruction to the letter. That said, doing it the way the manufacturer says makes the corners way too thick, but that is the reality of the matter. Thanks for doing these videos. If you try again, install the band first, wall to wall and then put the corner on top. That way you have your 2" overlap at all points. Thanks again Issac.

Schluter states that all seams are supposed to be overlapped by 2" which you did everywhere except where you butted the kerdi band to the corner pieces. The kerdi band should overlap the corners. The leak very likely happened at the seams that weren't overlapped.

Perhaps when you were flattening the kerdi band strip you put a pinhole in the corner with the trowel. I use a grout float with that stuff....just my thoughts on why you had a small amount of water in the corner

Nothing is like a well done hot mop. I have 3 for over a dozen years. It's roof material in your shower. The quest is to make jobs easier, quicker, and cheaper. For your own place, use a hot mop. These new systems will reveal themselves lacking as years go by.

You splashed water around the upper perimeter of your frame. That water had the ability to get between the frame and the drywall down the side and then onto the bottom sheet of drywall. This is why your bottom edges are wet. Kerdi is a great product. It's quick and easy way to dry-in a wet space.

Like to see that with Redguard or other waterproofing systems.

This was a good video. It would be cool to see performing performing same test on other systems like Wedi tile system to see their results.

this video was worth watching just for the 2 knife corner tip!!!

That a great test thank you! The way I do it is i wrap it on the wall, so that its a solid kerdi piece and theres no seem

It didn't look like you had a 2" coverage from your tape band over the corner piece in that corner when you installed your wall membrane. Was this also the wall where you had the bubble form?

One thing to think about is the corners should go on last. View it as flashing on a roof, putting the band on afterwards creates a lip in which direction the water is flowing. Similar to if you have to put a seam in pan liner you always want the lip to where the water goes over the seam and not running into it.

TileCoach - You are correct with your conclusion. A shower is not designed to hold water for 7 days. After 48 hours the design should change too a submersion design such as a swimming pool or hot tub. Schluter designed one for me which they specified three independent layers of Kerdi. Each layer required 50% sheet overlaps between independent layers. Of course this design was rejected due too cost and build up of inside corners. ARDEX 8+9 was selected which was designed by ARDEX requiring 3 layers of cross directional layers embedded in a fiberglass cloth. A 14 day flood test was performed with 500 gallons of water at 48" of depth. SUCCESS! Good luck with your ongoing tests.

Great test. No idea why this technique is used instead of a paintable barrier

I use this stuff quite frequently. I don’t use that seaming technique on the corners or up the walls. I cut a wider sheet of membrane or join two pieces down the middle overlapping 2-4 inches running the sheet up the walls 8 inches. For the inside corners I cover the membrane material with thin-set and then fold the material tucking it in to the corners and folding it into a miter. I squeeze out the thin-set and hold the corners in place. I made some wooden corner blocks to hold the membrane folds in place. I weigh the wooden blocks with bricks and push them into the corners so when the thin-set dries it leaves a tight inside corner. Tiles nicely. Makes a true unbroken pan. This way you minimize breaks in the membrane.

Run your base piece of Kerdi up the side walls 3"-4" and you eliminate that seam.

This is why I'm afraid to do a pan. We can send a man to space but can find the perfect material for these pans. Great job and much respect for your business and honesty. This is a small percent compared to all the ones you have done that came out perfect.

i appreciate the effort to do this test. as a student of construction, i will never trust a seam system period. its only a matter of time. i would only do a one-piece or liquid membrane but that's me. i know why he did this tho. he's telling you to study old homes and how they there constructed. when you tear down enough stuff, you will see what worked and what didn't

Awesome test . I like to redguard the seams . So it’s 100% sealed after using schluter .. your videos great proof that schluter is overpriced and overrated .

Great video man!! I have 35 years in the field doing mud work both mosaic and slab installations my company has torn out several of these products mostly due to bad installer mistakes or skipping steps or wrong application. Almost every time on a shower failure it is because of plugged weep holes. This is the reason why I use the same application on everything always hot mop always floated. You have good knowledge and really good RU-vid channel man take it easy.

The membrane held up great. You guys are good like your videos. I appreciate the no triple up on taping neatness and workmanship. The joint tape being the weakness I would find a way to tuck the corners and eliminate that leaking on another test. Considering doing a curbless shower on 3rd floor with an over lap layer from the wall down to the floor of shower as close to the drain as possible. Thinset over this double layer with inside corners embedded before a couple coats of aqua defense in corners and say a prayer before I tile it

Should have put the band first then the wall piece goes over that.It goes floor band walls so everything overlaps.But it works that way like you said because you won't have water sitting for a week.I have been doing this for 40 yrs and find the kerdi systems reliable.Good job guys!!!

The result of 7 days flood test is great but, I still feel very unfortunate with too seams, cuts. I think it's best with only one sheet of Kerdi and the corners is folded (no cut).

A wood float is really great to install the liner vs a blade.

Does make you question all the money spent on this system! If it wasn’t so damn readily available everywhere, 😆. Great video!

In France Schluter asks to use Kerdi-Coll-L (a bicomponent set) for the 2" junctions instead of thinset. as it has acrylic fluid instead of water, it will add more water proofing rather than the normal thinset. It costs more, but seems to be more suitable for extreme situations. would be nice to have the same test with that. tnx for the videos. p.s. in the test the water had a certain depth (10"?) that adds pressure and make it like a pool! something Kerdi is not made for.

Thank you Isaac ! I have drawn my own conclusion and I will share in the case that others feel the same way, I do not Trust kerdi completely, so I’ve in past and current kerdi showers I use hydroban on all kerdi seems, I have 1 more kerdi shower to build this month and I will be steering away completely from the system, this choice was my own professional experience, I will continue to mud my walls and deck mud over a vinyl pan , thank you for the video

Does this Makes you second guess all the previous installations you have done Isaac? I mean the test is extreme, no shower has standing water for 7 days (es there is no slope etc)....Perhaps the unmodified thinset dries too quickly and it cracks? Or perpahs because of the membrane layers it does not fully dries...... What about using a thinset that has a little polymer? or use an unmodified and add some polymer to it

Really appreciate the delivery of your messages and the knowledge you share. Your genuine honorable mindset is awesome!

Interesting test. I've used Kerdi, and always wondered about the potential for wicking through the thinset. IMHO, Schluter would be better off if they offered an alternative to off the shelf unmodified, whether that be a spreadable urethane product or something else. I'm thinking that a 4" strip of Kerdi board at the bottom of the wall assembly would provide enough of a barrier to stop wicking. It would obviously require another step, (and cost), but cheap insurance in the long run.

I'll stick with pan liners and wedi pans. I hate how kerdi has so many seams, you rely on thinset and it's not repairable....If you damage the membrane when trying to replace a chipped tile then it's game over....gotta redo the whole thing. You can easily cut the membrane when cleaning the grout lines with a knife and not even know you did it. Wedi pans are 100% waterproof. It remains waterproof even if you puncture it as long as you don't puncture it all the way through. The down side with wedi is that it relies on the polyurethane sealant to waterproof the seams. Pan liner is the safest bet.

I appreciate your straitfordwardness. Your right. The installer has to use his best judgement. Thank you for the tests. Very informative.

Smartest decision said right from the start: Laticrete HydroBan! I like Ditra, but Schluter crazy for thinking fabric adhered with a cementitious material is waterproof.

You may want to try Durock Cement Bear coat it is a water proof membrane troweled on.1 part Portland 1 part bear coat it is a moisture barrier.I am a stucco plasterer applicator up in Canada Toronto home of Durock.We normally use it on vertical walls before applying foam EIFS SYSTEM.Ive done a few experiment on my own home. One example I have a interlock patio I covered over top with this product then built my raised deck free floating with deck blocks on top now all is exposed and I'm talking long winter snow and rain.3 years now you can't remove it off the interlock if you tried only with a grinder.cheers good videos I enjoy learning new things.

Only thing I do different with Kerdi is I would lay the floor and then the preformed corner and then the walls , like step flashing

This is an awesome video! There was no overlap exactly where water got in. Bend was shorter and didn’t overlap with the corner. As you said... you didn’t want triple overlap, but that resulted in no overlap in that tiny section. I think you wanted us to figure that out :)

I'm very new in the tile game, but liquid waterproofers always made more sense to me. Liquids are rated for steam showers (Kerdi isn't, or you need some other thicker Kerdi sheet) and swimming pools (Kerdi definitely not.) Kerdi seems to be based on FUD (fear, uncertainty, and doubt) about liquids and also gets people who'd otherwise build something terrible (no taping cement board seams, no liquid on top or plastic behind cement boards, make a niche with tiles thinsetted to 2x4s or something equally nuts) build something correctly with their "free" training with their products, which to be fair, the other manufacturers don't push as hard. I think it also comes with the price of these products, people simply are more likely to read instructions if something costs more.

Not boring at all brotha many thanks 👍🏻

Its hard to get a perfect seal and considering how long the water was in there it did pretty damn good. If that was flooded for 7 days that would mean there are major issues at hand like the whole house has flooded

Kerdi is for tile people who can't build a proper, waterproof mud bed. And for the record, never say," I have been doing tile for ten years or twenty years". It is meaningless. I have been tearing out a lot of leaky showers for years, built by people who had been doing tile for over "ten years". Having built showers for years doesn't qualify you because you really have no idea if there was a failure in your history.

Id have to say that since it was only in one area and not on the flat bottom, its human error. I applaud you as this is the only way to learn wither or not a product works and if were installing it properly!

I always over done everything I make. I’ve only done one shower and that was 15 years ago and it’s upstairs over plywood. Perfect so far. Recently we redid all the plumbing and I could see under the show and behind it. No sign of any leaks. I never heard of any waterproofing membrane at the time so I didn’t go that route. Getting ready to do another one of our bathrooms upstairs this time I will Redgard everything including the floor.

Why didn’t you just install the Kerdi in one piece and flash it up? Also why didn’t you go over the seams with kerdi fix? Kerdi fix is waterproof and will seal the seam also in the Kerdi install manual

This is why you shouldn't fix something that isn't broken. If you know how to build a shower that is truly cementious and has a mud/mop based shower floor it will not fail. People have been doing this since before the inventors of schluter, kerdi, durock and all the others. Allow your shower floor to "breathe" the water as necessary. You should never be worried about standing water for any amount of time, regardless of any conditions. Tile/Stone install is very complicated, unique, and a high liability. Why try to save $500-$750 to hire someone who might not be qualified vs. a company/contractors who actually were doing it before the styrofoam/drywall stuff came out? Tile doesn't lie, and who you hire will directly reflect that.

Very helpful, I truly appreciate you and the time you invested to make that educational video. Thank you and god bless you brother😊

Man i really appreciate these videos, they’ve helped tremendously throughout my projects.🤝

I'm just an home DIYer, so I could be missing something, but it seems to me this test is placing the Kerdi membrane under conditions it was never designed to handle. As you pointed out it's a 7 day flood test (not 2 day) but also, a real shower pan is going to be sloped towards the drain. That means even if a shower is in constant, daily use, you will never have an inch of water continuously standing at the edges of the pan. So did water get behind the membrane? Sure..after 7 days. But push enough current through a wire and it will fail, over torque a bold and it will fail. Likewise, I think asking Kerdi to remain watertight under conditions it was never meant to meet seems unfair.

That small amount for 7 days "standing" water. I'm cool with the results. Any water to the structure?

Awesome Video going through your process and your final test and analysis of the test pan

Thats why I only use Kerdi. It took 7 times longer to get a fail. Great job on the test. 👍👍

Ive done many showers this way but i use 2 coats of redguard.or similar product over it and never had the slightest problem

Great test!! my only thought is that Im not going to line my pool with kerdi!! lol, BTW, I dont typically use sheet rock for any backer! My belief is that if you had used Kerdi board and kerdi pan and just Kerdi band would have been less time and less seams = less possible failure!

Good thing we're supposed to use cement board instead of drywall. For Standing water for 1 week, its still golden in my book.

Thank you for this post. I'm a tile setter in NE PA and these new Styrofoam waterproofing systems are starting to become requested. I absolutely needed a good video to share on how expensive it is and just how waterproofed it really is.

Two problems I have with this video. 1: You tossed the sharp putty knife onto the membrane a few times. That made me cringe. 2: There were a few gaps in the coverage on the top edge of the Kerdi band. This is most likely where it failed.

Ill stick with hot mop lath scratch and float i like my walls square and plumb before i set tile

Just makes me happy to see people trying different systems on there own dime and time!!

I love the videos and appreciate all the work One thing you might wana try though is making the pan longer so it can roll up the wall and then where you do the patches also roll those up the wall, then put a strip on the joint, and then take the wall membrane down the double up to the bottom or even down into the pan with its overhang

This system, i feel, is great in conjunction with waterproofing( redgaurd, aqua defense). Never had an issue, i like the test you ran, effective.

Kerdinwith a redguard 👍🏽

I don't care what anyone says, nor am I a contractor - but I believe the best way to go is to always install some sort of shower pan, acrylic, fiberglass, whatever have you, and then tile the walls if you must, or just use a fiberglass total surround or acrylic panels. I don't think TILE and GROUT on the base is a good idea! Water will always get in, and even with all of these space-age membranes it still gets in. I'm sure it gets in the walls too but they are never subject to the amount of water that the floor is with each and every shower. Just my .02 cents! There are always pros and cons......the nicest looking thing isn't always the best in regards to longevity.

Nice test What kind of system or materials you recommend for shower wall and base?