SpectraLOCK in the corners, can it really crack tiles? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-28-2007, 10:42 PM
Hey guys, it's been a few years since I was last on the forum. I'm back at it again, redoing the shower over at my in-laws house. This go around for some reason I decided to grout with SpectraLOCK. I went ahead and grouted it all except for the corners, which I bought some sanded caulk to use there.

The grouting went really well. It was just as easy if not easier to use than normal grout. It looks really good and I like the fact that it will not change colors when wet like normal grout. Plus it doesn't have to be sealed. Good stuff in my opinion, expensive but good.

So I laid tape down on all the corners and caulked with my sanded caulk. I smoothed it down with my finger and was going to pull the tape off. When I started to pull the tape, the caulk came with it some leaving a raised edge. It was getting late, so I just left the tape (big mistake). I came back the next day thinking it would have dried out enough to pull the tape and leave a clean line. This was not the case, now the caulk looks terrible. It pulled away and left a nasty rippled line of caulk.

I sooooooo badly want to razor out all the caulk and do the corners with the SpectraLOCK. Some people feel that the SpectraLOCK is strong enough that the tiles may crack with the normal expansion and contraction cycle. It seems to me like there would be enough play in the walls to absorb this expansion/contraction. How much can a 5 foot long shower wall really expand and contract? It doesn't seem like it could be that much, even with a 40 degree temperature differential.

My question is: Has anyone actually seen tiles crack when using SpectraLOCK in the corners or is this just speculation? Has anyone dared to grout their corners with SpectraLOCK? If so, sucess or failure?

I hate the caulk. It looks like crap and the color doesn't match well either. BTW, my substrates are slab floor and hardibacker concrete board walls. I taped all the wall joints and corners with hardi alkali resistant mesh tape and thinset before tiling.


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Tool Guy - Kg
03-01-2007, 01:48 AM
Ask Dave Gobis. I'm sure he's seen more than his share of this problem with his own peepers. :)

03-01-2007, 06:58 PM
Well Mr. Gobis (or anyone else) can I SpectraLOCK my corners or do I need to quit whining about it and recaulk it? I wanna know if someone has seen SpectraLOCK crack tiles. Maybe I should send it in to Mythbusters? :lol2:

03-01-2007, 09:03 PM
if all else fails, try calling Laticrete tech support. Would be interesting to hear what they have to say on the subject. :nod:

Rob Z
03-02-2007, 10:15 AM

It's not the expansion and contraction of the field of tile that is the concern (you're correct that 5' of tile won't expand linearly by very much), it's the movement of the strucure itself that necesitates the flexibility in the corners.

It's hard to find evidence supporting the argument that grouting the corners WON'T be a problem, in part because Spectralock hasn't been on the market for a long time and also because many people that are using Spectralock are possibly following the recommended practice of leaving the corners ungrouted. For example, even though we have used Spectralock on thousands of square feet of tile, we have never left a corner grouted with the stuff and thus don't have any experiences going back dealing with cracks or sheared tile.

I did call my Laticrete rep just now, and he confirms that he has seen a couple jobs with failures that he attributes to the installer grouting the corners with Spectralock. I have only seen Spectralock in corners on one job, but we tore the job out after only a few weeks because the homeowners had other serious problems with the original contractor.

03-02-2007, 12:36 PM
Well okay, I'll go ahead and recaulk. I did send an email to Laticrete tech support. They said of course that it is always recommended to use caulk in corners and change of plane. I was just hoping there would be someone that told me "yeah, I did it without any problems." That being said...

Does anyone have a good technique for smoothing the caulk out again after you pull the tape? Obviously, I'm guessing from my recent experience that you want to pull the tape ASAP. So do you just follow along the line again with your finger and hope it doesn't smear everywhere? Thanks,


Tool Guy - Kg
03-03-2007, 02:25 PM
Hi Austin,

We had a great discussion on caulking going awhile ago. Let me find it for you and post a link.

Found it. Anyone wanting to read up on how others caulk and smooth a joint, click here (http://www.johnbridge.com/vbulletin/showthread.php?t=20066&highlight=popcicle+stick). But I gotta warn you, get a comfy seat for this one. :shades:

03-03-2007, 09:03 PM
I was just hoping there would be someone that told me "yeah, I did it without any problems." well, given that it would look like an endorsement of a practice that would be contrary to TCA standards, I'm not surprised. But that doesn't answer the question about epoxy being hard enough to break tiles when a shift happens (as opposed to cracking the grout like Portland). Guess we'll have to wait for someone else to answer that one.

Rob Z
03-03-2007, 11:54 PM
Cement grout packed into a movement joint is plenty hard enough, or inflexible enough, to transmit the stresses of a moving structure into the bed of tile. Epoxy is even more problematic because it is "stronger" than cement grout, and it can glue the tiles together more so than the the setting material bonds the tiles to the substrate.

Several years ago, I was at an epoxy grout installation demonstration at a local supplier. The rep had a piece of quarry tile that was glued with epoxy grout at right angles to the base tile. Both tiles had been set over concrete with thinset, and when the job was torn out the pieces of base were edge glued to the perimeter floor tiles more strongly than either tile had been bonded with a premium thinset. The main cause of the failure was because the installers had filled the corners and the expansion joints with Laticrete SP 100.

I tried to break the tiles apart and compromise the epoxy grout bond between the two. The tile was a thick Summitville quarry tile that was used in a commercial application, and even so, the tile broke before I could get the grout to break off the tile. :eek: