Hey guys,

Am having a customer wondering if glass block can be installed in place on a bathroom window. Walls are double brick and it would be a tub enclosure as opposed to a shower.
Am trying to figure out how difficult it will be to reconcile the thickness of the exterior wall (+/-12") and end up flush with tile on the interior.
Has anyone anywhere with a winter pulled this off?
Am thinking it might be a tad chilly in winter. Also thinking that due to temperature there might be some shifting etc. that could wreck havoc on the tiles inside.

Thanks.

I have done a glass block window in the winter. The exterior had to be scaffolded and tarped in along with heating.
I would recommend you wait if possible for the warm weather.

Thanks.
I hear ya there, probably have curing issues also.
Was your window integrated into tilework in a bath or just a window?

Had to keep it heated for 7 days. The temperature outside was around -15C that week.
It was in the bathroom just at the edge of where the tile finished.

how did you finish the exterior?
and
did it work out the way you wanted?

This house had an exterior brick finish with 2x4 walls and plaster interior finish.
I used Pittsburgh Corning Decora series block 8x8x4" The ouside edge of the block was overlaped about 1/2" over the back edge of the brick. I was lucky on this one as all the finished dimensions of the glass left me a 1/4" clearance to the edge of the brick.
The inside of the block butted up to a custom set of wood jambs I made. the interior was finished with casing around the jambs.

If you have a brick exterior, its really important to make sure the block will fit between the brick opening, otherwise the reno becomes more complicated.

Yes, it came out just the way the client had asked for. I also did the whole front entrance of this home. I was pleased with the outcome.

Thanks Randall.

I'm still trying to reconcile how to finish the exterior side of the block.
Once the existing window and frame are removed I will be left with about 12" of exposed brick from the exterior edge to the interior edge.I will be framing a dummy wall on the inside of the double brick so as to allow the addition of some insulation and support tile backer and tile- this will only exacerbate my problem.
If the glass block is to sit flush with the finished tile, the inside edge of the 4" block thickness will sit at least 1/2" inside the interior stud wall leaving a gap and 12"s of exposed brick on the exterior. Does that help illustrate my problem?It's like your install only backwards, with the jambs on the outside.
Ideas I've had....
I could build another wooden frame inside the opening to properly fit the dimensions of the blocks and cap the exterior as with a normal window. The "well" will be so deep I'm not sure I want to rely on aluminum and caulking to hold out the elements.
or...
I could fab what would basically be a tiled niche out of cbu and kerdi around the bricked opening. The glass block on the interior would be like the "back" of the niche. This seems highly problematic though.
or...
Could a standard fixed vinyl window be installed in the bricked opening to the exterior and glass block installed as a completely separate system on the interior dummy wall? There would be only one vapor barrier on the inside, with kerdi over the edge of the backer into the sill around the block. I'd have to install a custom jamb to go between the two and paint it well before the block went in, but I dont think that would lock any vapor.

There are many ways to do this I'm sure! I want the best one.

If you were to do a double glass treatment, ventilation holes would need to be drilled in the jamb from the exterior to the air space between the glass panels. This would be the same concept as a Pella window, only on a larger scale.

I probably would push the block to the exterior brick side and use the extended sill as a niche if the glass block dimensions worked out.

Okay.
So in this scenario the glass block would get installed first (dimensions allowing) as described in your post, and instead of jambs and trim on the inside would be a niche.
Simple enough. I just want to clarify that the cbu would then butt up against the glass block and get silicone, kerdi/tile then grout/silicone?
With a regular niche the back and inside are waterproofed as a whole and here there would be a butt seam with a huge temperature differential. Just troubleshooting.
What if there were two courses of block (exterior/interior) with brick weepers in the outer course?

I would also build a niche if I were doing it. If dimensions permit, start with a fairy thick layer of mortar under the blocks so that you don't eat into the first block too much with the sloped backer and tiles. I would redgard the niche, because I am more confident in that bonding to the blocks.

Just to clarify Pete, you would redgard the blocks?
Does redgard come in clear?

No, that's not what I meant. The glass blocks are essentially water proof. I meant waterproofing the niche. You could make the niche out of cement board butted up to the glass blocks and then water proof the CB with redgard right up to the blocks. Then tile the return and silicone the joint against the glass.

This approach lets you adjust the size of the opening quite easily and you are not stuck tying to adhere a little strip of kerdi to glass.

Update on the situation-

Customer found someone else for the glass block.

Other guy says he plans to frame in opening to proper dimensions (an option I rejected) with PT lumber (!), install the blocks on the inside and cap the outside.
1) My understanding of PT is that it should not be sealed in or capped, as it needs to breathe and will tend to dry up and split and twist. 2) Also, why PT? If water gets in there, there will be bigger problems before the wood ever rots.

As a constructive suggestion should I suggest he use KD?

This plan will essentially be not much better than the original wooden window frame but will have to work with it (and hopefully learn something about installing block).

PT is a bad choice. It should never be used for interior framing. It will likely warp or twist as the over 19% moisture content starts to dry out.

This installer is already starting off with the wrong proceedures. I'm not so sure your going to learn the correct methods for installing glass block.