Bathtub to shower conversion, w/mortar bed and kerdi walls [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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06-02-2019, 11:14 AM
First timer here remodeling a small bathroom. Biggest part of the project is going from a tub to a walk in shower. They also had a drop down ceiling over the tub that I tore out.

So far the tub, wall tiles including durock was all ripped out. Could not do much about drain location but was able to move it a little from the shower wall so the center of the drain is 3.5" from the Left shower wall where the shower head will be. I used 3 2x4s for the curb and read all the opinions on pre fab curb, using bricks, etc but it seems the bottom line is if you waterproof it correctly you should not have an issue.....I hope. The drain was .5 inches above the slab so my pre slope bed at the thinnest was 1/2 inch by the drain to 1.5 inches thick on the right side wall of the shower. After putting in my linear drain the thickest of my slope is 3.25 inches leaving just 1.25 inches between the top of the pan and the top of the curb at its thickest point. The slope is all good at 1/4 inch per foot.

Question #1 is do I need to build of my curb more or just allow for the mortaring of the curb and threshold to add about another 1 inch?

Question #2 is I bought Kerdi board for the shower walls. I see mention of using furring strips to allow for the folded corners. This shower sits at the back wall of an 8'x6' room so if a shim the kerdi board 1/4 inch then the kerdi board and the drywall outside of the shower wet area will not match up...any ideas? I thought I could perhaps shave away 1/4 inch of the back of the kerdi board to account for the pvc liner folded corner bulge. Would that work?

Question #3 is when I put the kerdi board on, do I run it right down to the shower pan or leave a 1/4 inch gap between the bottom of the shower pan and kerdi wall board?

Question #4 is once the kerdi boards are up i need to the the kerdi band from the bottom of the kerdi board onto the shower pan, about 2 inches on each surface using an unmodified thinset to do this, Is this correct?

Question #5 is with the kerdi boards and using the band on all seams and screws and corners should I also use the kerdi membrane over my curb?

Thanks in advance for all of your help. I have spent numerous hours scouring the forums and watching dozens of videos to get to this point.

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06-02-2019, 07:29 PM
Welcome to the forum, Chayne. :)

First things first:

Are you using a PVC liner for your waterproofing layer on the floor? If so, why? Considering that you have Kerdi board on the walls, is there some reason you wouldn't do a single mud bed on the floor and cover it with a piece of Kerdi?

06-03-2019, 05:50 AM
Yes, using a PVC liner. Original plan was to use durock. Switched to the Kerdi board after the guy at the Tile and Decor store talked me into using it and how easy it is use with its lightweight etc.... at that point my pan was already in place

06-03-2019, 05:52 AM
to add... I called Schluter to ask how I could use the board with a mortar bed and they suggested the kerdi board should be right down flush to the mortar bed and then use the kerdi band ......just wanted to be sure that is the right approach

06-03-2019, 06:58 PM
Question #2. Usually we recommend to notch the studs. Here's a link. Scroll down to post 13.