Window in shower - Waterproofing methods? Pics.

[Frank Drebin]

Ok, I've got my own project going on but my parents are redoing their tub surround at their house, and have a nice big window that they figured that they had to tile over it...I've attached some pics...it would really be a shame to cover that up IMO.

This is what I figure would be sufficient protection. (questions in red)

• Tub surround in 1/2" Hardi; seams and corners taped with Kerdi band
• Kerdi wrapped from 1/2" backer over top of vinyl window surround. Will thinset/kerdi stick to vinyl? If not that leads into the next point.
• 1/4" hardi sloped on bottom plane of window to aid in draining. Can the 1/4" hardi be attached to the window sill with just silicone or thinset? Can the use of screws be avoided?
• Corner where tile meets vertical plane of window to be sealed with silicone.

My reasoning for this method:


The tile/silicone is the most vulnerable to leaks. If there is a leak through the silicone, it would reach the vinyl casing of the window (which I'm assuming is weatherproof from the inside as well), and meet the kerdi where any water will be kept from the backerboard. If I went hardi then kerdi over the hardi, the water could migrate between the hardi and vinyl casing and essentially be "under" the kerdi membrane.


My concerns

1. The window should be weather (ie water) proof from the inside, like it is from the outside?
2. Freezing - if moisture gets in behind the silicone close to the window pane, could cause some damage if it freezes. Not sure if it's cold enough though.

[Davy]

I would probably go ahead and nail the backerboard in the window, cover it with thinset and Kerdi. Then use Kerdi-Fix to seal the Kerdi to the vinyl window. Kerdi-fix will stick to about anything but make sure the surfaces are dry.

[Trask]

Hardie and kerdi with Kerdi fix to seal is a fine plan. No need for Silicone if your Using the Kerdi Fix.

[Frank Drebin]

Originally Posted by Davy

I would probably go ahead and nail the backerboard in the window, cover it with thinset and Kerdi. Then use Kerdi-Fix to seal the Kerdi to the vinyl window. Kerdi-fix will stick to about anything but make sure the surfaces are dry.

So...Kerdi fix instead of the silicone bead against the window?

Can this stuff be trowelled on to stick the kerdi to the vinyl window for reasons stated above?

Or is it kerdi over hardibacker, then kerdifix on the seam between the hardi and window, then tile, then kerdifix on the tile/window seam again?

[Frank Drebin]

Originally Posted by Trask

Hardie and kerdi with Kerdi fix to seal is a fine plan. No need for Silicone if your Using the Kerdi Fix.

How would you suggest I secure the hardi to the vinyl casing? Thinset sufficient? I don't think the vinyl casing has too much holding power for screws.

[Davy]

I was thinking there is wood behind the vinyl that will hold the screws, is there not? The Keri fix comes in a tube like silicone. Use a bead of it to seal the edge of the Kerdi to the vinyl.

[Frank Drebin]

So like this then?

Kerdi fix I have is in an ugly grey...would be nice to have matching silicone, and the kerdifix is still sealing, the silicone is more for aesthetic purposes?

[Frank Drebin]

Originally Posted by Davy

I was thinking there is wood behind the vinyl that will hold the screws, is there not? The Keri fix comes in a tube like silicone. Use a bead of it to seal the edge of the Kerdi to the vinyl.

I suppose if a guy uses some 3.5" deck screws you'd hit the framing that the window is attached to?

[Davy]

A small bead of Kerdi fix against the vinyl will be covered with tile.

[Davy]

Maybe I don't understand but looks like the window has to have 2x4's framing it.

[Frank Drebin]

Originally Posted by Davy

Maybe I don't understand but looks like the window has to have 2x4's framing it.

Nah you're probably right, I don't know a lot about window construction all I know is when I've hung blinds they basically are hung by the vinyl and that's it.

It must be a wood frame capped with vinyl though, you're right.

Thanks

[Frank Drebin]

Originally Posted by John Bridge

• Aluminum windows have been used with some success, and the newer vinyl frame windows are really great.
  
• You might wonder whether thin set will stick to hard, non-porous surfaces like window frames, but I’m here to tell you that it will.
  
• The lower corners of the window opening (where the sill meets the side jambs) are treated with corner pieces. The upper corners of the window opening are not critical, since little or no water will ever splash that high.

I guess Mr. John answered my questions in his book.

If posting exerpts out of his book is against site rules mods please edit this thread.

I'm gonna stick to original plan. Kerdi to window casing, maybe a smear of kerdifix at the interface.