Is your contractor/glass installer planning to "sink" the notched panel into the bench? If so, that would provide additional support.

We are still trying to work out an option that they are comfortable with and that we like design-wise. The bench is already built and has a quartz slab on top...would "sinking" the panel into the bench still be possible?

Sure! They just route it with a stone saw. That's what the glass installer did to the granite tub decking that extends slightly into my shower to provide add'l support to the notched piece of glass that fits into it. Currently, my shower floor is being re-done, so here's a picture of the notch in the granite (top of the photo; had to shoot through the plastic tenting -- sorry, but hope you can see it):

Sinking the panel into the surface while giving it more support will not give it the support in the correct place to make it structurally sound. You will need to either use a support bar like you have pictured or a header. That setup up is to large to not have some sort of support at the top (as you have found out). Without this support this will definitely wobble. And I would consider using 1/2" glass as 3/8" maybe a little too thin for this application (for the fixed panels at the very least).

I'm assuming you won't see this as it's been 3 years, but I wanted to see how you resolved this because I have the same question.

So glad you saw it! Thanks for the super fast response.

How much gap do you have between the ceiling and the top of the glass panels? I will have about 5-6 inches. Can't go all the way up (I'll spare you the details). I don't want that big honking arm that looks like a handicap ADA device on the glass panel and totally blows the frameless vibe! I asked my contractor to come up with a clamp at the top of the panel that extends vertically into the ceiling and looks benign. Glad to hear you have had success going without. I may do the same. Just a channel on the wall and one on the shower curb.

We have just under 23" between the ceiling and the top of the glass. Our ceilings are 9ft high. Let me know if other questions come up, and good luck!

I bet your shower is gorgeous! Thanks again. My panel is only 4' x 6.5'

frostyfootball, did you end up using just the wall and curb channels? If so, how is it working out? I have the exact same issue and don't want one of those ugly support bars.

I opted to use the curb channel and a support bracket running from the glass to the ceiling, not across. It's not even noticeable. I have a small ventilation opening above the glass so it worked great.

Frosty football can you post a picture of how yours turned out? I’m dealing with the same issue and think a bar from the ceiling may look better. Thx

No support bar hope it works out our contractor said we didn't need one