I think you are mistaken the width of the curb - large as you call it - with practical when cleaning the shower floor or even use it as a step. Other than aesthetically a narrow vs. large curb doesn't serve any purpose.I have been chatting with Leo here about his installation methods. I have recommended he cut down his Kerdi Curb so it is not so high. I did a blog post on the subject and laughed out loud when a member of John Bridge's forum suggested a trampoline to get into the shower built with a Kerdi Curb. He was kidding of course (I think) and so that everyone understands what I'm talking about lets look at this monster of a shower dam they call a Kerdi Curb.
When looking at these massive shower curbs build from foam I wondered if because they are so huge - this is part of the problem with water wicking into the seams. The Kerdi curb looks a good 6"-8" high in the photos. My curbs I build out of bricks or concrete and are only 2"-3" finished - with tile. So under flood test I have a gallons and gallons of less water in my builds.
Maybe all Jim's ranting about head water pressure is coming to shed som light on this problem of water wicking into the Kerdi Seams. Lets take a closer look at the monster curb Schluter calls the "Kerdi Curb"
No this shower was not built by me but rather built by or for one of Vancouver's local tile shops. What a piss poor showing of the Kerdi Shower System. Maybe not the system but certainly the quality of work. This washroom was on my top five worst bathrooms in Vancouver - it was nasty. Now it's cleaned up, but look at the quality of the job.... so poor.
See how poorly the Schluter tile profile was installed. This is a common mistake rookies make. Not using the right size profile for the tile. Man that curb is ugly....
The inside looks worse than the outside!
Photo Source - Page
So Jim - do you think because the Kerdi Shower Curbs are so huge - that this is adding to the problem with the kerdi flood test?
Looking at that picture it would require over 22 gallons more water than I use for a flood test. A 3" difference. That is like 4.5 buckets more. 22 gallons of water will add over 175 pounds. If I estimated the shower right at 36"x48". Not sure if I'm doing the math right but that makes only 0.1 pounds per square inch.....
This Kerdi Curb is even bigger. OMG that is a tool box waiting to be tiled. Photo Source
Now this is how a low curb should be done. Out of cement and Kerdi. This a photo I took when I dropped of an ACO linear drain to KBC Developments out in White Rock. See how the tile pro build a low curb shower. Used cement. Did not make the curb look like a tiled tool box but rather s sleek minimal design. Awesome work.
If a kerdi Curb was used here I think there would be over 800 pounds more water in the shower for the flood test. But you think the Germans would have planned for this. Yet another reason to build the showers like they do in Germany..... With Kerdi Coll. Not non-modifed thin-set...
No curb or curb less is a different story .