Exterior Slate Cladding

CJKarl

OK here goes. Have a customer with some "unique" ideas. This is new construction. Part of the home incorporates giant concrete retaining walls. About 15' high and some up to 60' long. He wants to Latapoxy 1/2" slate tiles directly to the concrete.

Here are some of my concerns. (my main work is high end residential masonry, but I've never done anything quite like this)

Control joints, because of the huge area of tile?
Moisture wicking through the concrete and getting behind the tile?
Should I just tell him to hire and engineer and think about some kind of mechanical anchoring system?

I stand behind my work 110% and call backs are not an option. If it takes more time and more $$ to do it right it's not a problem.
So anyone that has done any cladding like this just throw out some ideas and things to watch out for.

Thanks in advance,

Karl


This is in CT, wicked freeze/thaw cycles.

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CJKarl

Silverblue

Finish shown in photo: Cleft

FLOORING APPLICATIONS:
Heavy Commercial Traffic
PRICE: Low range for Slate and Quartzite
COLOR: Black
MATERIAL: Slate and Quartzite


STOCK FINISHES
Cleft

SPECIAL ORDER FINISHES
UPON REQUEST

STOCK SIZES
12x12
16x16

SPECIAL ORDER SIZES
UPON REQUEST

USES
Exterior Cladding
Exterior Pavers
Interior Floors
Interior Walls

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angus242

If you used Ditra over the concrete that would eliminate the moisture/minerals leaching through into the slate. Ditra is waterproof. Address your (Ditra) seams with Kerdi-Band.

I saw an 8' retaining wall done like this in AZ. Only difference was that wall was built with concrete blocks.

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SLSTech

Per the TCNA W202- waterproof membrane required (I would agree with Angus above - DITRA) Movement joints required every 8' to 12' in each direction - I would also go with Schluter & color matched caulking

Sorry, but I can't help you on the freeze thaw part - I have only done these types in AZ where it rarely freezes

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angus242

Schluter makes some decent movement/surface joint profiles:

http://www.schluter.com/141.aspx

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CJKarl

Good ideas, I did a huge 3/4" slate floor for this guys brother and used Ditra.










Never thought of it for vertical use.

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CJKarl

Here is a panoramic I took of the project. The 2 pictures don't line up perfectly, but you can get the idea.The main part of the house sits on those 2 beams. You can see the large retaining wing walls in the foreground, two slightly smaller ones on the other side of the house. He wants slate tile both sides and top so it looks like one giant piece of slate sticking up out of the ground. I live for projects like this.

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CJKarl

Use my helper and F-450 for scale.

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angus242

Yep, them are some big walls!

I would think Ditra is the answer to this problem. Download the Ditra handbook and look at pages 20-21:
http://www.schluter.com/media/brochu...k-2008-ENG.pdf
That will help you will the movement joints.

Perhaps even call Schluter 800.472.4588 and throw this idea by your rep.

That's gonna be A LOT of non-modified thinset!

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olzo55

As much as I like Schluter products, I would consider two other products as well. Noble makes Noble Deck sheet membrane which I believe allows you to use a Modified thinset over. Also, Laticrete has a roll on membrane for exterior use and again a modified thinset could be used. If it were me, I'd choose a modified thinset for outdoor use. And, of course, install some type of control joint system.

olzo

CJKarl

Going to ask the rep about TROBA also. What if moisture is trapped behind the Ditra? Could it fail?

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angus242

I can't see how TROBA could be used. It's designed to be laid loosely over a waterproof membrane and then have a mortar bed laid on top of it.

I don't see moisture being trapped behind DITRA unless that entire wall will be wrapped in stone and therefore, wrapped with a vapor barrier. As long as the back side of that wall doesn't have something to trap moisture in it, you should be OK.

Olzo's suggestion is good too. Not sure what you'd spec for mortar so that may come into play with your decision of what membrane to use.

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CJKarl

OK, I didn't fully read the TROBA description. I thought is was like Ditra, with drainage built in.
My question on moisture is because these walls are retaining earth with unknow drainage behind them.

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R&D Tile

Call Schluter, as far as I know, Ditra is for floors only.


Look into Kerdi, Hydroban, Redgard or Nobles sheet membranes for walls if you need waterproofing and crack isolation.

angus242

Schluter does allow this. I think your only issue is what type of thinset you want to use. I doubt that the Schluter guys will sign off on modified. So you need to choose the membrane based off that. Schluter = non modified, others = modified.
Call the 800 number and Kathy should answer. Ask to talk to either Bryant Bouchard or Rich Crito. Not sure which handles your area. I'm sure one of them would come take a look at the site in person and give you their recommendations.

Sounds like an awesome project! And if you get this remember, Angus has trowels and levels, experience with Schluter products, has laid plenty of slate and might like a change of working environment scenery for a while

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R&D Tile

What, Ditra on walls?

angus242

Ditra on walls?

I've talked to Schluter about this, have you?

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Angus
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R&D Tile

No need to, how would you fill the waffles in the Ditra on a wall and have it stay?

That alone would be a waste of time, thinset and effort, use a product made for this.

angus242

Wait a minute, RD. I was replying to your comment that insinuated Ditra can't be used on walls. So...

Can Ditra be used on walls? Yes.
Are there other products that are made to be used on walls? Hell yes.

So the debate should be, what would you use?

It's like talking about what thinset do you use. There are different kind, all work in roughly the same manner, with some being better than others.

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Angus
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R&D Tile

Ditra is NOT recommended for walls & serves no purpose trying to use it there, even Schluter states that.

I would probably use Hydroban for this installation.