John, just did a kerdi shower in my own home.
Good for you Boardable. Building your own shower is a great milestone in your own home!
Used Kerdi board and kerdi styrofoam pan with membrane and kerdi drain. Of course after the board is all in, niches cut and sealed I read about the kerdi baord.
What did you read about the Kerdi Board?
Water tested a piece and it seems to be fin even when exposing the raw edge to water.
Exposing the raw edge of water will soften the "Reinforcing Layer" (looks like press cardboard MDF) and allow water to wick through this layer. This will weaken the board by about 30% - 50% by my test results.
Thank god it is a stud wall so hopefully the screws will hold it in.
You did use the special Kerdi Screws and Washer System right to install the Kerdi Board? Regular screws will not cut it!!!
I used kerdi fix and applied it to all the seams that will or could leak on the kerdi for the flood test.
Did you do the shower floor and walls? Did you Kerdi Band all the screw heads and every seam?
I went with a very generous 3-8 inches of overlap so that I could be really sure of sealing.
Sealing Kerdi is a touchy thing. It needs to be perfect to work. 3-8 inches is a lot. How much of that was no-modifed thin set and how much was Kerdi Fix? I have been complaining for years about this seaming system using just non-modified thin set to seam these sheets. When I installed Kerdi I always hit the seams with Red Guard. That was a decade a go when we started. Since then my approach has improved and uses many different products to built what specific showers my clients need.
It has always bothered me that Kerdi is installed different in Europe. In Europe they seam the product with a cementious waterproofing product much like Ardex's 8+9. I have never been exposed to these products until about a few weeks back and really like what I'm seeing. To understand the difference you need to watch both the North American installation video and the European installation video. When you see the installer mix the Kerdi Col this is like Ardex's 8+9
I am reading this post and just not sure If you like Kerdi or not.
This thread is about flood testing Kerdi - Your water level should not drop over 72 hours of flood testing. You need to measure for evaporation and plug the drain so that it's connection to the vertical portion of plumbing pipe above the P-Trap is tested as well. I like Kerdi. Love Kerdi Band. Kerdi-Fix is my favourite waterproofing product but - I hate Kerdi Board and seaming Kerdi with non-modified thin-set. I hate that people say Kerdi is Hydrophobic, because it's not. And I feel the lower quality setting materials contribute to effloresence in a shower floor - causing the grout to go white or lighten up.
If the pan passes the flood test I am going to redguard the seams just for extra peace of mind and lay the tile.
Skip the Red Guard. By a small unit of Ardex 8+9 and give the entire shower floor a coat. Use a little on the wall seams and save enough to coat the floor out twice before tiling. Ardex's thin-sets are pretty amazing as well. We are using X32 for a bathtub project and love the stuff. Pretty quick setting (we are mixing a bag in six lifts to keep it creamy).
I am not researching into Wedi and it looks like a great product.
This product is on my short list to try as well. I have been trying to secure training for months with no success. I'm still waiting for the next Vancouver session.
I have built many bath surrounds with CB and even shower stalls using the vapor barrier method and never had a problem.
We see so many that hold up like champs. Mostly the nasty business is in the shower pan or when drywall is used in the shower. Cement Backer Board and Poly are field proven successful methods. That said a topical system is superior in my opinion.
I wanted to try a totaly waterproof shower so that is why I tried kerdi. Not sure how the outcome will be.
If you flood tested and installed the product with care you will be fine. If you want added protection then use Ardex 8+9 as a safety net. You can double your five year Kerdi Warranty if you use the Ardex system. Maybe call the rep and ask if you can still get it if you use their X5, X32 setting materials and their grout.
Tha major question is : Do you like kerdi or not?
Yes I do. Again - I like Kerdi, Kerdi Band and Kerdi Fix.
I do not like non-modifed thin-set as a seaming product. Think about it - Noble Company advise against this process for their membrane. Noble Company uses a product called Noble Sealant 150 (regular or low VOC) to seam their membranes. This makes a waterproof connection that still offers up some flexibility. I've used it and love it. Sometimes a shower floor's pitch is tighter and a sheet membrane just doesn't want to sit down so flat (try pushing a sheet of paper into a soup bowl - it crinkles). A liquid membrane is much easier to install here. Liquid membranes are tricky to apply perfect and coverage rates need to be followed. I'm finding on hot days liquids are not the best approach as they are drying to quick.
Being introduced to Ardex's 8+9 and X32 has been an eye opener. Finally a setting material company that embraces Schluter and goes as far as to double the warranty. Now in my shower kit I can get the best of both worlds. Kerdi as a reinforcing fabric in my corners. Kerdi Fix - my favourite shower waterproofing product. All the prefab corners inside and out. Just seamed with 8+9 (how it's done in Germany). And the kicker.
YOU CAN FLOOD TEST THE NEXT DAY !!! or in as little as 4-6 hours (yet to be proven or tested by me)
And am I better off next time laying up CB and painting on liquid redguard and using a wedi preformed pan?
Depends on the project. Lets look at that when it comes up.
or a Kerdi pan and drain and CB and redguard.
Kerdi system only - 5 year warranty
Kerdi and Red Guard Hybrid - No warranty
Kerdi and Ardex 8+9 system - 10 year warranty.
Red Guard is like $65.00 here in Vancouver for a small bucket (70 square feet). Ardex 8+9 is $100.00
For $35.00 more you can go from having no warranty to a ten year one. You need to use their grout and X32 or X5 thinset I believe. Email this guy - he can send you your local Ardex rep's name and number : Robert Russell < Robert.Russell@ArdexAmericas.com >
Just looking for your ultimate bullet proof shower recipe and Opinion on whether I just made the biggest mistake of my life with Kerdi ?
Relax!!! You checked your work with a flood test. Your golden. Protect the shower floor or set it first.
Good Luck with the tiling!