bemum, what is the frame of the window made of and is that what you seek to protect? Glass (tempered glass, I hope) needs no extra protection and so long as your tiling is sound and the SEALED grout intact, then only the frame is at issue. Is it metal painted wood, vinyl> Each has its own merit and considerations.

bemum, can you post a photo?

We just want to take all precautions for waterproofing. The window is vinyl. Here is the set-up pre-tiling. Some privacy would be good too, although not entire necessary.

I am struggling to do a similar bath. My initial thoughts...is it tempered glass (code compliant)? obscured glass (for privacy)?

Why would this window need to have tempered glass?

In my area, I believe building code requires tempered (safety) glass in this type of application. But bemum can confirm that is the case in their area with their code inspector.

A double hung window such as this presents more challenges. Water will sit on the sash and you'll need to keep on top of that. I would be inclined to swap this out for a casement window (assuming you want it to open) or a single pane of obscured (or partially obscured) glass.

Windows in showers will always leak. It's not a if, it's a when. I'd relocate the window outside the shower area. And yeah, it needs to be safety glass even if it's located outside the shower and it's still within X'' of that shower. Slips and falls are a fact of life in damp locations.