Bonding mortar for stacked veneer stone? [Archive] - Ceramic Tile Advice Forums (2024)

reanimated

11-07-2011, 09:50 AM

Hi all,

This is basically another "thinset vs. masonry mortar" question for veneer stone.

I am doing an exterior wall using an artificial veneer stacked stone (the veneer stone is manufactured from concrete). Especially because it is a stacked stone without grout, I would like to do a good water proofing job. I would love to use the laticrete MVIS system, but I can't easily get their products, so I am trying to come up with an alternative.

I have installed 1/2 inch permabase over sheathing and I plan to apply Mapei Aqua Defense as an alternative to Hydroban. My question is what mortar should I use to bond the stones? Mapei lists Kerabond/Keralastic as the correct product, but I can't get those locally, so I was thinking of using Keraset/Kerapply as my thinset choice. I am pretty certain that would provide excellent adhesion for the stones. I called the manufacturer of the stone to ask about this, but they are pushing metal lathe plus scratch coat as the only acceptable installation method, and also said that "thinset is too strong and will crack the concrete-based veneer stones." Maybe that's true, but I just didn't get a strong feeling of confidence in the person I was talking to... plus I have already put up the permabase and I'm not taking it down to put up lathe at this point ;-)

The other option would be to use the Sakcrete masonry stone veneer mortar, but their technical sheet says nothing about applying it over CBU, not to mention a water proofing membrane.

If anyone has advice on how to proceed I would really appreciate it!

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bbcamp

11-07-2011, 11:35 AM

Garth, you don't want to listen to the folks that made the product you are installing, but instead, you'll ask advice from some folks you met only on the Internet? Do you think our warranty is better than the manufacturer's?:shades:

You want a total system approach for this job. Since you are interested inb Mapei's products, give their tech support folks a call: 1-800-992-6273 (U.S. and Puerto Rico) or 1-800-361-9309 (Canada).

reanimated

11-07-2011, 12:09 PM

Thanks for the reply bbcamp.

I actually listened very carefully to what the person on the phone said, and just because I posted here doesn't mean I will automatically take just any advice that is offered ;-) I am trying to collect as much information as I can and make the best decision I can based on it. The person I talked to had never heard of such a thing as installing adhered masonry on a CBU and dismissed laticrete's MVIS as nonsense. After hearing that, do you think I should just do what that person is telling me and nail up a metal lathe, throw a stacked veneer stone on it and let the water have at it?

I did call Mapei's technical support, and they do have an architectural drawing for this application using CBU, AquaDefense, and Kerabond+Kerelastic to set the stone. The problem is I can't get those products locally and the stone manufacturer is saying that thinset should not be used. That is why I came here to hopefully get some other perspectives from people who have done this sort of thing.

bbcamp

11-07-2011, 12:16 PM

We're probably not the best DIY website for you, Garth. We tell folks to follow manufacturer's instructions or industry standards. We certainly won't tell you to do something the manufacturer specifically advised against. Sorry.

Typically, a layer of builder's felt is placed behind the lath for a waterproof layer.

Who makes this stone? Is there a website? Is this stone product even rated for exterior service?

Hammy

11-07-2011, 01:06 PM

Where in NC are you located that you can not get LATICRETE products? The guy you talked said LATICRETE MVIS is hog wash cause he is un educated in new products on the market and is stuck in the old ways. Mortar has no tensile strength to keep stone stuck to the wall. Mortar has compression strength. Just a tid bit of info.

Hammy

reanimated

11-07-2011, 01:44 PM

Hi Hammy, I am near Raleigh. I could not find any retail stores that carry the MVIS products, but I learned through DalTile (which is located right near my house af all places) that I could order through a local tile place. However, it would take time and I'm under some pressure to get the job done this week. That was just poor planning on my part.

Bob, I appreciate the point about not wanting to appear to go against manufacturer advice or industry standards. I can tell you that using the Sakrete masonry veneer mortar was approved by the person I talked to, and their own installation instructions say to add a "bonding agent" for groutless applications. So I can change my question to this: is Keraply the kind of thing they would be talking about? (It is an acrylic latex admix). If I mix that with the Sakrete mortar, I wonder if that would do the trick?

Thanks.

Hammy

11-07-2011, 03:54 PM

Garth, they are requiring a " bonding agent " due to the lack of strength in the mortar. Since this is a groutless there is nothing to hold the stone on the wall except the mortar behind the stone. Brick mortar is made for stacking bricks/block etc.The bonding agent is painted onto the wall ( cement board, scratch coat etc ) so the mortar will bond better to the surface.

Personally I think you need to slow down on the job and do it right after more research. Rushing into it due to time restraint might mean redoing it again in the future.

Watch this video http://www.laticrete.com/mvis/

Got a question for you.......... What is going to keep your stones from sliding down the wall til the mortar sets up?

Hammy

ceramictec

11-07-2011, 04:35 PM

Mortar has no tensile strength to keep stone stuck to the wall. Mortar has compression strength. Just a tid bit of info.:nod:

109585

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Lakee911

11-07-2011, 08:00 PM

I'm getting ready to install a similar product -- dry stack ledgestone or ledger stone from Anatolia tile & stone in an interior application.

The manufacturer's instructions say, "For all installations, a polymer modified mortar is recommended. For commercial installations, as well as exterior installations over 10' in height, a polymer modified mortar with a latex additive is strongly recommended." http://www.anatoliatile.com/pdf/stone/ledgestone_screen_p.pdf

Of course, I'm thinking what the heck?

(No this isn't why I was inquiring about mortar in my other thread...)

reanimated

11-07-2011, 09:23 PM

Jason, those instructions sounds like exactly what I was thinking of doing. The sakrete veneer stone mortar is polymer modified and I will add an acrylic latex admix.

Those are nice pics, exactly what I don't want to do :shake: That doesn't look like very good coverage on the stones to me?

Hammy, I have seen that laticrete video before, and as for your question it seems to me that if I am using the right materials, nothing should be needed to keep the stones from sliding down except their adhesion to the wall (and I'd like to work top down for at least part of this job if I can). This is how I got here in the first place, because I understand the bonding mortar is important for this application and that plain old type-S brick mortar is not going to do it.

Lakee911

11-07-2011, 09:59 PM

It still seems a bit odd to me, but it's their product and their instructions.

Is an S mortar really necessary? I know little of mortar, but my understanding is that S would be the least sticky type. Maybe an O at the other end would be better? I guess what type is in a sakrete veneer stone mortar?

Lakee911

11-12-2011, 08:45 PM

Can someone recommend a polymer modified mortar and a latex additive? I went to bLowes and they only had normal (unmodified) mortar. I checked in the tile department and the guy said they had modified thinset mortar which I don't think is correct.

I'm going to add the latex even though it says for commercial apps (how a wall can be any different in a commercial app than a residential app) since I'm assuming that it is better.

Thx,
Jason

Davy

11-12-2011, 09:00 PM

Fat mud is strong within itself but doesn't have much bonding strength. I would use a good modified thinset on the stone and on the wall with the fat mud in between. Make sure the thinset is wet when the mud is applied.

I try to have an open mind and learn all I can but II have never heard of a thinset being too strong and that will cause the cement based stone to crack. If you put the water proofing membrane on the wall, it's gonna take a modified thinset to bond to it.

Jim Doane

11-13-2011, 02:13 AM

Lakee911

11-13-2011, 09:21 PM

Interior app over concrete backer board.

bLowes has Laticrete, TEC and Mapei products. TEC Latex additive.

Why not add latex to polymer modified product like instructions say?

Thx.

bbcamp

11-14-2011, 05:41 AM

Lakee911

11-14-2011, 07:35 AM

Oh! Well, that's a good reason. :)

So, what to use ... those pics have me scared. We were discussing last night if the whole install just fell over like those pics. Disaster!

Jim Doane

11-14-2011, 07:18 PM

Lakee911

11-15-2011, 08:59 AM

ceramictec

11-15-2011, 02:58 PM