I’m in the midst of a shower reno and whilst I’m not doing it as a DIY job, I’m hoping you folks can help me understand why my shower hob needs to be so high.

Here is an image of what we say today: shower hob shower hob 2

We were expecting something more like this: small shower hob

I messaged my plumber (who is managing the job) to ask about this and his response was that it needed to be high to hold any moisture that may get under the tiles and that had we done a full reno then we could have had what we were expecting.

I don’t quite understand how the hob will hold water that gets under the tiles, if water is going to do this then isn’t it going to get under the floor of the shower as opposed the the edges of the shower?

The shower that was in there previously was a raised acrylic base shower that had cracked after the previous homeowners had done a dodgy job of having it installed. They also had not waterproofed the walls or shower floor, which we’ve had done as part of our reno.

My plumber is not great at explaining things or replying to things, hence why I am asking here :).

  • I've never actually seen a shower like in your final photo, and I've built and seen many high-end homes. I don't think I'd trust it at all unless it was built as paul describes below, and even then it seems like a recipe for unpleasantness.
    – isherwood
    Jul 5, 2018 at 13:06
  • A walk-in shower needs the entire floor to be waterproofed and sloped to let water drain. Doing that will require breaking up the existing flooring. Jul 5, 2018 at 15:30

1 Answer 1


The hob, or curb, lined with that rubber membrane you see there, exists to contain water. Imagine your drain gets a little clogged with hair like shower drains will do, and it starts draining slowly and water stands in your shower. It’s just there to provide a buffer of safety.

The membrane is in place to catch water that gets under the tiles and bring it to the drain, which it will, because grout and mortar are porous materials. Your plumber was probably referring to this.

The second photo, what you were hoping for - that bathroom likely has a rubber membrane under the entire bathroom floor, and the entire bathroom floor is likely pitched towards the drain.

  • Thanks for the explanation! That makes sense. I think the missing piece for us was understanding why ours was so big when the one we were comparing it to was so small.
    – James
    Jul 5, 2018 at 20:47

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