Shower window flush with framing [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-22-2019, 04:48 PM
Hi Everyone,

Thanks for you willingness to advise and brainstorm.

I'm working on a bathroom with a vinyl replacement window to be installed in the shower. To waterproof it I'm thinking of prepping the old wood window frame (the "rough opening" for the new replacement window) with some type of traditional rubber with adhesive, paint, or other waterproofing (any suggestions?) to send any water that gets in the window to the exterior. I read some suggestions to wrap kerdi membrane into the "rough opening" before installing the window, but seems to me like another type of waterproofing here would be more suited for wood than kerdi and that wrapping kerdi over a slope toward the shower on the inside of the house and then under the window on a slope away from shower on the exterior of the house might be problematic.

After this I was going to use kerdi membrane over cbu on the shower surround walls, wrapped into the window recess and kerdi fixed to the vinyl window frame. The main issue is that the vinyl window frame is just about flush with the wall framing.

Do you all have experience with this?

The sill extends into the room about 1.25" from the window frame. Is this sufficient for a thin strip of cbu? I could fur out the window wall, and even use two layers of cbu for that matter, so that the wall makes a nice 90 degrees with the end of the window sill. What recess amount is ideal to try to achieve with the aim of tiling right up to the vinyl window frame? I see that there exists pencil tile trim that I could use here, or perhaps a quarter bullnose type tile, or even a Schluter edge trim?

I was also thinking of nixing the recess, cutting the wooden window jamb as flush as possible with the vinyl frame, installing a single plane of cbu up close to the window frame and trimming the window with some simple pvc molding. I just can't picture how to waterproof the window frame/cbu junction well.

The picture shows a replacement window installed (I'm going to do it again because there is a weld split in the vinyl frame).

I'm also going to see if I can use this window in a different part of the house, so that maybe I can make the shower window smaller and only up high.

Thanks everyone.

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03-22-2019, 05:41 PM
I'd use some 1x on the walls to bring it out a little, then wrap the framing of the window with whatever wall board you're using. What you want in the end is for the Kerdi to be about 1/4" or so over the window jamb, which would be sealed with silicone or other sealant.

Kerdi won't adhere properly to wood, so everything has to be covered with some type of tile backer.

For what it's worth, sheetrock is a suitable backer for Kerdi, and it's what Schluter recommends. It's much easier to work with, and less expensive. However, if you prefer to use a cement board, that will work as well. It's good to know ahead of time that installing Kerdi over cement board is much more difficult, especially for a newbie, since CBU draws moisture out of the mortar very quickly.

03-22-2019, 06:30 PM
I'd approach it in a different way. Remove the old window frame and install a fixed window, creating a sill on the interior which will act as a niche as well. Movable sash on shower window is a yuck collector, although bulk water should find it's way out via the weep holes built into vinyl frame.

Old window frame would not be my preferred starting place. Most are not tied to the house frame all that well.

Actually, I'd make my own frame and have tile and waterproofing running up to glass, but it's more work and possibly a little daunting for one new to the game.

Kerdi board makes for a good window surround.

03-22-2019, 07:14 PM
Thanks Kevin and Peter.

Kevin - are you saying Kerdi needs a minimum wrap of 1/4" into the jambs or is that as far as you usually wrap it? I was going to wrap it all the way to the vinyl frame and adhere it there.

note taken about the drywall in place of cbu. like others, I'm not sure if I'm entirely comfortable with drywall and read that Durock isn't as thirsty as Hardie.

Peter- this window is one of those that wasn't tied to the frame well, it seemed to be floating. I added some framing on the sides and adhered the wood jamb to this framing and added some sill supports. Perhaps I can find another spot for this replacement window and look into changing strategies completely like you suggest.

Kerdi board as a window surround - do you mean in the jambs butting up to the window? or lining the jambs before window installation?

03-22-2019, 07:42 PM
Here's how I usually treat windows. Also put kerdifix where kboard meets window.

Sent from my VS987 using Tapatalk

03-22-2019, 07:52 PM
Thanks Ryan, that's mostly what I had in mind, minus the Kerdiboard.

I'm going with 3x6" subway tile which I guess is relatively cheap so I'll have to take another look at using Kerdi board in place of cbu. seems pretty slick

03-22-2019, 07:58 PM
On a separate note, the bathroom tub doesn't span the entire width of the room. I thought that I could use this to incorporate a nook out of the side wall by the shower head while still providing a continuous floor to wall surface for a shower curtain.

Will this present any difficulties that I, as a newbie, can't even imagine?

03-23-2019, 05:03 PM
Should be ok, I dont see any real issues.

03-25-2019, 06:53 AM
Thanks Ryan.

Another question:

I can get rid of a small strip of tile in my layout by tiling about 1 1/2" shy of a full 3' of cbu width. Will 1 1/2" of cbu and then the cbu to greenboard transistion be difficult to finish and paint over?

03-25-2019, 09:01 AM
In a dry area you can finish that joint and CBU the same as a drywall joint and it should be equally invisible.

My opinion; worth price charged.

03-25-2019, 09:17 AM
Great. It's 6 in. outside of the curtained shower, so I'll plan on that.

03-27-2019, 06:59 AM
Is there any advantage to designing the shower surround wall one way or the other?

The tile would either be set parallel or perpendicular to the tub - any difference?

And in terms of waterproofing and possible water run off to the floor from the tub?

Any thoughts? Thanks again.

03-27-2019, 07:03 AM
Also, decided to use Kerdi board, would have liked to try the Durock system, but it's a bit of a drive to pick up those components.

03-27-2019, 07:25 AM
The Durock Shower System components are available from Amazon, Leighton.

03-27-2019, 07:53 AM
Concerning design and intersection of elements.

I find it's almost always better, both looks-wise and execution-wise, to offset surfaces rather than trying to keep them in plane. There are exceptions, of course, but it's something to bear in mind.

Houses and components of houses are not truly square, flat, coplanar, level or otherwise perfect. This coming from someone who wants them to be, 'cuz his first jobs were in cabinet shops...

03-27-2019, 07:58 AM
Thanks CX,

I decided on the foam backer as opposed to the cbu or drywall and membrane as it seems the costs are comparable and the former cleaner and easier.

In such, I ruled out shipping and delivery of Durock's panels. I see the membrane up on Amazon, but not the panels.

I think I'll stick with Schulter, Durock for the next bath.

05-02-2019, 10:59 PM
Hi all,

I've just about finished furring the bathtub/shower surround back/window wall out and will now start on the side wall framing.

I have to sister a few of the 2x4's on one side wall because they're not 16 OC for the Kerdi board and because, in one corner, there isn't enough stud exposed to accommodate a Kerdi screw and washer.

Given that there's a wire run through the side wall studs, will non continuous sisters amount to a secure enough attachment point for the Kerdi?

I was going to run a sister alongside the existing studs from the ceiling to just above where the wire runs through the stud and then again starting just below the wire down to the bottom plate. With enough fasteners and even adhesive, is this adequate?


05-03-2019, 05:48 AM
The non-continuous sister will be fine, Leighton, it isn't load bearing so it only needs to support the weight of the foam board and tile. A fist full of #9 X 3" construction screws in a zig/zag pattern down the face of the sister(s) will be more than sufficient. Add adhesive if it makes you feel better.

05-03-2019, 08:18 AM
Thanks for the reassurance Dan.

I got the back wall pretty dialed in - flat and plumb. What approach do you all recommend for getting the side walls 90 degrees to the back wall? I measured the 3-4-5 triangle and the walls are actually pretty good. Is there a more precise method, without any special tools?

05-03-2019, 09:13 AM
Squaring the end walls to the back wall can be tricky. It's unlikely you'll be able to move the studs in the back corners so you'd have to alter the plane at the front. Depending on the layout (and the extent of your demo) dong that may result in a lippage issue where the backer board meets the drywall.

Really depends on how out they are.