Hi guys,

I am currently updating our guest bathroom shower. In an attempt to reduce the scope of work, we are keeping (reglazing) the existing bathtub, but we are tiling all the way to the top of the ceiling. I have removed the old tile and drywall at the back and sides of the shower and I have them down to the studs.

The plan is to put cement board as a substrate (Durock) overlain by Schluter Kerdi, overlain by 3x6 Subway tiles. For the edge of the tile, I was planning to put a Schluter profile.

Now I am in the phase of putting back the walls together prior to tiling, and I ran into a small issue. The bathtub does not exactly fit the space available. As such, when placing the cement board over the tub, there is a tiny space (about 0.2 inches) behind the cement board. This causes the proposed cement board and the existing drywall to not match, as shown in figure 1 below.

I forgot to mention, to make sure the cement board is vertical, I will need to shim to make up for the gap using roofing felt, unless you guys suggest something better. I tried looking into alternatives, but I could not find a piece of wood that would help with this tiny space.

In order to close up the space and make up for the difference, I was wondering if you guys knew of a product or profile which could help hide the difference, such as a corner profile. Please see Figure 2 below.

Can you guys think of a different/better solution? I haven't been able to find a profile with that shape. There are plenty of T moldings for floor transitions, but I haven't been able to find anything similar for walls.

Would you still do Figure 1 and put caulking in the edge?

I really appreciate your help and opinions.

Thanks!

 

You would use a wide knife and use joint compound to float the drywall out to meet the schlueter edge.

At any rate, I don't know why it is so much thicker... cement board and kerdi should be about flush with drywall. You don't put the cement board over the tub flange. You shouldn't need to shim. Some guys tape the flange with a butyl window tape (like protecto wrap) as a flashing. The cement board then sits on top of the flange.

 

First is the problem with your tub's flange/lip. Instead of shimming at the bottom to get the cement board out the 1/4" you need to get over the lip I shim the entire wall. This way you end up with a straight/vertical corner and a straight line where the tile ends at the edge of the shower. If you just shim the bottom you end up with a ski jump shape that never looks right and causes more trouble for finishing.

As for an edge strip like you sketched all the edge strips I'm aware of are designed for a flat surface or 90° corner. What you sketched would be a custom piece because of your odd step back dimension. I would look at pencil or edging tiles or consider doing some other type of trim.

 

Yes, I do agree. That is why I labeled it as "ideal solution".

The plan was to shim all the way up to have the wall perfectly vertical, but this would cause an edge all the way to the ceiling, since the backer board would not match the drywall next to it.

Does this clarify?

 

So if I understood correctly, is this what you mean? (Sorry, I am a visual guy and needed to create a sketch )

If done this way, the backer board would not need any kind of shimming, and it would meet the thickness of the drywall, making a flush transition joint with the Schluter. But then there is the issue with the gap behind the Kerdi. Would you suggest some sort of band to fill in that gap and caulk the top and bottom?

Thank you for your extremely valuable opinions!

 

Who says the gap is an issue? Look at any tub / tile diagram. It shows the cement board on top of the flange and a gap.

I am saying the flexible protecto wrap flashing is what some people use to flash the flange. If you are using kerdi, follow their directions. There are plenty of youtube videos from Kerdi.

 

If you're using Kerdi, they recommend Kerdi Band to cover that gap and Kerdi Fix (silicon caulk-like stuff) to fill that gap behind.

https://images.homedepot-static.com/...677fdc571b.pdf
Page 18 and Page 31

If you do still have a mismatching for some reason, it has worked for me to extend the tile an inch or two over the drywall. Then get a deeper metal edge to make up the difference and end up with a thicker coat of thinset. Of course it depends on the design on your bathroom, but it's an easy fix if you can extend the tile out a bit further.

 

I did what you suggested. I came up with this picture from Pinterest. Do you think this would be a feasible solution in this case?


I am not using a liquid membrane, but still it would be wise to caulk that area, right?

Thank you!

 

That is typical, yes.............