Backer board and solic surface shower floor question [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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04-27-2008, 07:33 PM

I've installed a Swanstone 36" double threshold corner shower floor.The instructions seem to indicate that I should caulk the seam between the 1/2 Hardibacker and the lip which it rests on but doesn't overlap.

See pg 2 Diagrams :"typical through the wall detail with an alternative wall covering application" and "Cross Section"
sorry I was unable to insert a jpeg.

I'm worried the if/when the caulked seam fails moisture will enter here.

I could shim the backer board out to permit an overlap

Any suggestions are appreciated.


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Tool Guy - Kg
04-27-2008, 09:02 PM
You have options.

Yes, you can go ahead and caulk the Hardibacker to Swanstone flange that you are talking about. Remember that it's up 3/4" higher than the shoulder of the Swanstone pan, so water that got past a failed caulk joint at the bottom of the tile wouldn't be able to travel uphill and exploit a cracked joint that you're concerned about. Use 100% silicone at the joints and rest easy.

On the other hand, if you can fir-out the studs so the Hardi can overlap the flange, that's good as well. Some folks prefer this. For me, the logistics of shimming out some walls in some situations creates another problem.

Another option is to notch the studs so that the nailing flange fits into the studs and your Hardi can overlap the flange. This would be my first option if all other things were equal. :)

04-28-2008, 06:59 AM
Tool Guy,

I was going to apply redguard over the backerboard. My concern is any moisture that penetrates the tile will migrate down the redguard and be either trapped at the bottom seam by the silicone or or work its way into the wall rather than be directed back into the pan. Am I being over cautious?

Since the pan and drain are already installed, your first two options are all thats available. I'm leaning towards caulking it.

Could I caulk the seam and then cover it with Redguard? I will have to put thinset and tile overtop anyway. The redguard would cause any vertical migration back into the pan.

Am I missing anything?

Thanks Again