Installing glass block window in shower [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


View Full Version : Installing glass block window in shower

08-27-2001, 03:10 PM
I am renovating an upstairs bathtub/shower to repair damage from leaking inside window sill. Want to replace existing standard window with 4" thick glass block preferably flush to reduce chances of another disabling leak. Size will be approximately 40x32 inches smaller than original window. Construction is 2x4 walls, 12 centers (after repairs), and eventually Hardibacker with moisture barriers. Would I be better off mortaring each block in place, buying custom glass block insert, or buying custom block window with vinyl wrap frame? (I have had a vinyl wrap window delivered to house, but it has obviously not been sealed properly for a wet installation and Im considering taking it back.)
This site is outstanding!! Thanks in advance for your help!!!

Sponsored Links

John Bridge
08-27-2001, 03:19 PM
Hi Mike,

I'm a mud man, and the only way I've ever done glass blocks is with mortar. I do use the plastic spacers, though. They are excellent.

I do blocks like I do tile. I strike out the mortar, and then grout both sides the next day with sanded grout. Turns out a dynamite product, but it's not the easiest thing to do.

Maybe someone else has had experience with the other methods you mention. Check back a little later.

Bud Cline
08-27-2001, 03:49 PM
Extruded aluminum....maybe, but I gotta go now.

08-27-2001, 05:00 PM
I've never done Glass Blocks but have had a few requests for it.What about cutting them? Can you? What with?.....Wet-saw?

Keith(lost as a Easteregg)Alford

Rob Z
08-27-2001, 06:16 PM
Hi Mike

I have gotten glass block made into a panel several times, and then moved the whole thing into position into the window. The panel has a big strap around it to help hold it together. It was far cheaper than paying a mason to come in and do it in place. I recommend waterproofing the opening with a trowel applied membrane (there are many brands).

Glass blocks can't be cut with a wet saw or any other method, and filling the struck joints with grout like John says looks really nice.

I did see one of those vinyl clad type units you mention, but I didn't think it looked very nice.

Bud Cline
08-27-2001, 09:12 PM
I have used the same extruded aluminum used by glass companies for store fronts. Depending on the structure and thickness of the exterior walls, it may be possible to use the "C" shaped material. Some of this stock has a 1-1/2" flange which gives some leeway in adjusting the size of the opening. I siliconed the metal in place. Then also set/stacked glass blocks on plastic spacers while at the same time using a large bead of silicone to assemble the blocks. Being carefull to leave room for mortar to tuckpoint the blocks after the silicone sets up. The only trick is in trying to apply the proper and consistant amount of silicone because some glass block will show the difference in color of the silicone and mortar/grout.

08-30-2001, 10:26 AM
I have used the glass block "kits" with the silicone caulk. In fact I used it in this exact situation. I took out the rotting bathroom window, reworked the opening to fitthe glass block, and went at it. I think I did it after dark and in the winter, so this stuff is pretty fool proof. Or at least joeboy proof!!! he he
Then I put tile on the rest of the wall, and used sanded grout to fill in the areas between the glass block and the tile.
I hope this helps................

Mike Fossum
08-30-2001, 02:47 PM
Thanks for all the comments - I really appreciate it!

Unless I'm missing something, it sounds like the vinyl frame window was a bad idea. Think I'll peel off that expensive frame and mount the panel of blocks directly in the window. Still hasn't been roughed, so easy to adjust. And lesson learned cheaper than having to do this whole job again. (It's my house and I plan to be here a l-o-n-g time. Cost of making it "bullet-proof" is not major concern.)

If anybody has had good luck mounting the vinyl windows in shower, I'd like to hear about it before I get out the hack saw.

John Bridge
08-30-2001, 03:28 PM
In re-reading I notice I missed Keith's question about cutting.

No, you can't cut glass block. If you did, moisture would get in a fog things up. In fact, if you ever get a block that fogs, it's a "leaker." Throw it away.

They do make half blocks and end caps. They make 45 and 90 degree corners, also.

08-30-2001, 03:47 PM
That's o.k. John.I'm used to being ignored.I'm married with three kids.....need I say more?

I should have realized about the fogging.Had a "duh" moment.

John Bridge
08-30-2001, 04:55 PM
No, Keith, the cutting thing is a reasonable question. Married with three kids now, well, I'll have to think about that one. ;)

08-30-2001, 06:21 PM
Well, I really didn't think you could but wasn't 100% sure.
A customer I had installed tile for wanted to put glass blocks in a window frame but didn't want to do any wood work.The dimensions just would not allow this.Actually it was his neighbors house.I never heard what they decided to do.

John Bridge
08-31-2001, 06:04 PM
Next time you run into it you should know that glass blocks are made in just about every modular size -- 8x8 is the most common, but there are 6x6, 4x4, and 12x12. There are also 4x8, etc. Some of these are hard to find.

In most cases, though, when it's a retrofit, you'll have to adjust the opening and do some carpentry.

Or, give the customer my well-worn line, "Hey, I'm a mud man, a mason. I don't mess with wood, you know?"

Mike Fossum
09-03-2001, 10:50 AM
Since there has been some interest, thought I'd follow up with the info I got from Seattle Glass Block, makers of the vinyl wrap window frames.

I have spoken with two of their tech reps to get details about installing vinyl-wrapped window in shower. Both times, they led me to the conclusion that I would be happier to just install the block panel directly into window opening without the vinyl frame. Window frame should be waterproofed, as if setting tile in it. Recommended setting the block panel flush with tile, using inch cedar shims to set it up, then using non-expanding foam on bottom and sides. Push any foam that tries to expand out back into place. Top will require foam spacer caulked into place. Trim ends of shims that protrude. Tile around window. Seal edges with good caulk.

I asked about using mortar, instead of expanding foam, because I have seen that recommended. Guys in Seattle both said the expanding foam would work better, but I didnt get the rationale. Suspect its for better waterproofing.

Since I already have the custom-made vinyl framed window propped up against a wall in my dining room, I guess this the price to pay for a good lesson in doing all of the research first, but a lot cheaper than starting over in my bathroom in a couple of years. Still doing the rough work (as well as reading John & Mikes books and TCA handbook) and open to any more words of wisdom.

Thanks! Mike

John Bridge
09-03-2001, 12:20 PM
lay the block up with mortar. It'll take you a while, but that's the advantage weekend warriors have -- time. Nobody's paying you, so take your time.

They actually make a glass block mortar. You should be able to find it where glass blocks are sold. It is off-white, and looks really good when used properly.

The mortar can be sealed just like tile grout. They're be no problems with leakage.

09-03-2001, 04:05 PM
I've used the glass block mortar..nice stuff.
It is pretty tricky to build though especially for a novice. Might be better off to just buy a premade one coz after doing all that work it comes out the same or even in many cases cheaper tahn buying every separate block and the mortar ,not to mention the time involved.
Unless you talking custom of course.

The foam is just for setting the finished window into the opening. I agree it is a far better method also for that.

John ever see 12x12 glass block, I did on this one job what they did was use it on the floor in the middle of a dinning room and put a couple 12x12 ceramic borders around it..looked sweet you could see the basement.

John Bridge
09-03-2001, 04:55 PM
Yeah, I've seen the 12 inchers installed, but I've never done it. A guy once had me use 6 in. blocks for the riser on a step-up into a whirlpool tub. He rigged colored lights behind the blocks. I'm an eclectic, but it was a bit much for me.

I think, with the plastic spacers, a guy who can tile a shower ought to be able to stack up a few glass blocks.

09-06-2001, 09:56 PM
Are you guys implying the vinyl framed windows leak when installed in showers?

I have a client with a new home under construction that has a vinyl window(with blocks) in the shower. Funny thing is the blocks are not glass....They are plastic. Doesn't look that bad to me.

I intend to tile the shower window sill as well. Is backer board with felt paper below sufficent. Of course plenty of silicone where the CBU meets the window.


09-06-2001, 11:27 PM

I don't know about vinyl-wrapped windows in general, but the one I had made for me in Houston definitely would have leaked. There was not a good seal between the glass blocks and the frame. This would have allowed water down into frame with nowhere to go but up into the block mortar causing staining or, worse, down onto the window frame. I was also concerned about how well the joints at the corners of the frame were sealed. I could blow air into them, so water would find it's way in, too.

Local guys weren't much help. Could have added more silicon caulk, but I had doubts about it's long-term ability to stay sealed when added on the top rather than firmly pressed inside.

I called the Tech Reps at Seattle Glass (makers of the vinyl frame material) two times. They didn't come out and say the frame wouldn't work, but both of them led me to the conclusion that I would be happier without the frame.

It could be that my application is a bit different than standard -- in discussions I told them I was worried about water intrusion in window ledge and was considering routing out the back of window frame to allow window with nailing flange to sit flush with tile on shower wall.

I'll let the real pros respond to waterproofing the window ledge, but can tell you up front that it will be best to apply a sealer to the inside surface of backerboard.

Good luck!

-Mike Fossum (DIYer)

[Edited by on 09-08-2001 at 09:30 PM]

09-04-2004, 09:11 AM
The issue with vinyl windows: If I may, any window opening should be wrapped with waterproof paper. But in areas that are under direct water abuse constantly, I like to use that adhesive backed rubber flashing. I'm not sure of the actual name of it, but it comes in a roll 12 inches wide by 20,50 and 100 ft lengths. very easy to work with and reduces the amount of staple holes in those areas because of the adhesive sides (which have a plastic skin that you remove once it is set in place).
My preference from that point is wire, mud and set. All the new age stuff is handy and quick but noone can say that its better than the old-fashion way!
If its your house, and you plan to stay..... no wonderboard, hardibacker or wonderbacking whatever........FLOAT IT! plumb-level-square, Be done with it..
Rick from
Epic Tile & Stone

John Bridge
09-04-2004, 10:22 AM
Hi Rick, Welcome. :)

I think the material you're talking about is Protecto Wrap flashing.

Listen, stop into the Professionals' Hangout and introduce yourself. We can always use another mud man. ;)

Oh, you should register, too. Lot's of bennies in that and no risk whatever. We don't sell info or anything like that.