Niche With Marble Shelf [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-25-2008, 03:05 PM
Thanks to the wealth of information on this site, I'm about done tiling my tub surround (porcelain over kerdi). One very minute detail I've failed to dig up from this forum or the JB Kerdi Shower Book is what to do when it comes to grouting a shelf in the niche. Do I "suspend" the shelf with thinset leaving gaps between shelf and support tiles to be filled with grout like in picture A? I suppose nobody sees under the shelf, so maybe B is easier? Or is there a different way? Also, I'm using sanded grout for the shower, but I bet it won't play nice with a polished marble shelf. Can I use un-sanded grout for this duty and expect it to adhere to the sanded grout in adjacent joints? I guess I could also use silicone, but I think grout would look nicer. Any ideas/advice are greatly appreciated! Thanks

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John Bridge
02-25-2008, 04:39 PM
Hi Jamie, :)

I rest the shelf on the tiles and prop the rear up with a couple pieces of tile spacer that I trim with my knife. The rear of the shelf is no more than a sixteenth of an inch higher than the front.

I grout the entire niche with sanded grout. You won't see the microscopic scratches in the shelf. Eventually it'll be abraded anyway by simply removing and replacing the bottles, the razors and everything else that might go on the shelf. :)

02-25-2008, 05:51 PM
Like john, make sure that the self is tilted so that water drains off the shelf and does not flow back to the wall.

02-25-2008, 06:41 PM
I use some spacer wedges I have to hold the shelf up a little until it can dry and gap grouted

02-26-2008, 03:01 PM
Thanks for the replies everyone. I appreciate the insight on grouting... makes sense that any scratches suffered during the process will wear down with daily usage of the shelf.

I should have mentioned that I was planning on pitching the shelf slightly into the shower for drainage purposes - thanks for watching my back!

02-26-2008, 08:08 PM
as an aside to this question, when i sheetrock my niche before kerdi-ing (is that a word?), can i simply shim the back of the sheetrock on the shelves about 1/8" to obtain the proper pitch for drainage?



02-27-2008, 05:06 AM
Yes Kerdiing is considered a verb.
If you mix a bit of thinset to place under the rock, it will work. Just make sure it's pitched correctly.But don't try to nail into it before it dries.

dan j
04-01-2008, 08:07 AM
I'm also doing a marble (or cultured marble - whatever Lowes sells) shelf in my niche. Is it ok to just use sanded grout for marble shelves? And, as long as I'm here, and hopefully this isn't considered thread hi-jack, the wife now wants a marble sill for the doorway. Can I use the unmodified Keribond (over Kerdi) to set it or do I need something special?

04-01-2008, 06:20 PM
You can use unmodified for the threshold, unless you're going over a sustrate that needs a modified thinset,like a membrane, or plywood.Grout is fine for the shelf...and yes you hijacked :yeah:

dan j
04-02-2008, 07:16 AM
I'm an innocent bystander - don't shoot! :)
I figured that asking here was better than starting a new thread. And, I did ask about this in thread on my shower.

When you say "unless you're going over a membrane" - the Kerdi is a membrane- but you meant some other brand of membrane, right? Any worries about bleed through with it or Keri's or Spectralock grout?

Ok, so I'm a thread hi-jacker :jacked: Here's my original thread

John Bridge
04-02-2008, 08:10 AM
Dan, yes. Any good qualify un-modified mortar will work. Now get back to your own thread. :D