Glass tile rain?

[JoeC]

Just had something new happen.I did a glass tile backsplash last month. The Tile manufacturer spec'd out Custom's B.P. "MegaFlex" as the " recommended" Thinset. Had no problems with install other than it was hard to cut w/o breakage. part of the install was tiling up the sides to ceiling and wrapping the top of the garden window header. . Got it done, and a month later 2 tiles above the sink on the underside of the top of their garden window just fell off and landed on their brand new granite counter top. This was a first for me in my 34 year career in Los Angeles area. I've never lost one from the ceiling, even during the 94 earthquake. Was very careful to key in the mortar, and made sure the T/S for that part was very fresh, not dried out, etc. etc. Wanted to cover ALL the bases!The top area was drywalled , but I decided to install 1/4" Hardibacker just to be extra sure of a good bond. The Thinset had small cracks all thru the areas where the tiles had been set.
Any ideas? Going to call the Tech rep, but wanted to post it here to get your thoughts first. JoeC

PS, the tile was very smooth 3"x 12" clear glass with a solid white, smooth coating covering the back

[TileArt1]

In my experience small spider-cracking behind where the tile was set is indicative of the substrate sucking moisture out of the thinset before it gets a full cure. Did you sponge down the backer? It should be SSD - Saturated, surface dry.

I've only used the megaflex a couple of times but can't remember much about it. Pretty sure I didn't use it for glass.

[dhagin]

Originally Posted by Joe

The top area was drywalled , but I decided to install 1/4" Hardibacker just to be extra sure of a good bond.

1/4" hardi on a ceiling? How was the hardi installed?

[Higher Standard Tile]

Dana I think he installed the Hardi on the wall up to the ceiling, not on the ceiling.

Never used Mega Flex but sounds like great stuff, I think Roger might have point with the Hardibacker sucking the moisture out of the thinset too fast.

Did you caulk the inside corners and against the window frame? Glass needs room to move.

[JoeC]

Hi, thanks for the responses!
The Hardibacker was sponged down just prior to setting the tiles.
I had made that mistake back in the 90's of not dampening HB before spreading thinset and didn't want to repeat that mistake over a brand new granite countertop 4' below! . Also, the Hardibacker strip was only for 1 course of tile across the top. About 3.5 " x 44". Thinset above the HB, with Rok_On screws, and then the thinset on the bottom side of the HB, as well as a skim coat on the 4 pcs. of tiles themselves. I made sure that the tiles were firmly set and bedded in the mortar with 100% contact. Adjusted them flush with the vertical tiles on the wall above to the ceiling above the window , and then made sure there was no sagging or movement. Since it was a rainy day, I waited for a couple minutes or so, standing right there on my bench, then taped them all so there would be no movement or sagging. JoeC

[Tiger Mountain Tile Inc]

If it wasn't bonded well there's a good chance you would find out when you go to grout. Did you tap on any of the other tiles around it? Are there any bond issues with those?

[John Bridge]

Going back to saturating Hardi-backer, I've done several Kerdi showers with it (bonding Kerdi to the Hardi-backer). I can recall sponging over the backer board as many as five times before the water stopped disappearing on contact. If it is not completely saturated it will suck water out of your mud.

[java]

I really do not see the appeal of using Hardi for anything.

I loath the stuff really.

[Scottish Tile and Stone]

I agree with not enough saturation.. That stuff is very thirsty

[Art of Stone]

I am suspecting expansion as it does not sound as if the tiles still installed show cracks from shrinkage. It is my understanding that sunlight can play a big role in expansion though gladly, I have not encountered this before.

Is there space allowed for expansion, free of grout, around the installed perimeter?

[RipRap]

Was there any TS adhered to the back of the fallen tiles ?

how about contamination on the tile backs - oil, soap film, mold release, etc. that prevented the latex from bonding.

[dhagin]

Lets see some photos, Joe. Substrate, tile backs, perimeter joints, etc.....

[John Bridge]

My reason for using Hardi-backer was that it is straight, stiff and flat. I know there are other boards that are suitable. I'm not a backer board guy, anyway. I'm a mud man who likes membrane showers.

[K_Tile]

Temperature swings during set time can play a big role in lack of bonding with glass tile.

[TonE]

Wat John said.. That and I can cut it wit my electric scissor thing that makes basically no dust..
you do this long enough and anything no dust is good.