I just bought a Schluter Kerdi-board prefabricated shower curb for my new shower pan, because I was finally impressed by enough stories about shower curbs failing due to wood expansion and contraction. The Schluter curb arrived, and it appears to be made up of a foam board of some sort, that won't expand when/if moisture wicks in there. However, there is some give to it. It isn't completely rigid. When I step on it, there is a noticeable deflection. I am very nervous about installing solid, rigid tile over a soft foam board.

It's hard to believe the folks at Schluter don't know what they're doing. But it seems like such an obvious failure ready to happen when somebody heavy steps on this shower curb. Can anybody reassure me as to the theory behind building up a curb with material that will give under normal human weight? Or should I return this and just form up my curb with concrete?

1 Answer 1


I have used the Schluter products, Specifically the curb. While I had my doubts as well, the curb has remained intact in a neighbors home for over 3 years with no issues. I recommend at least 3/8 inch thickness of thinset over the product when setting your tiles vertically and 1/2 inch on the top for the curb cap.

That said, I also built shower curbs from wood and lath. From wood and the plastic curb framing. From poured concrete and from bricks. I haven't had an issue with any of them.

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