# heavy slate tile as an exterior wainscot



## drbabs (Jul 3, 2011)

Recently I have seen two homes with slate tiles for exterior wainscot. 
Frankly, it looked really good. 
why is this not used more often? real and fake stone products are common on exteriors. slate is relatively common on roofs- why not exterior walls?


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## JBM (Mar 31, 2011)

Maybe because it has bonding issues.


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## CJKarl (Nov 21, 2006)

In researching materials for the big cladding job I'm doing I found out that some slates contain natural "oils" and adhesion is an issue.


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## drbabs (Jul 3, 2011)

JBM said:


> Maybe because it has bonding issues.


JB, 

I see other tiles used in modern looking commercial offices and high rises. But if its adhesion, I guess this makes sense. 

but wait, how does our setter get it to stick onto the ceilings of showers and baths with all the moisture?


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## JBM (Mar 31, 2011)

drbabs said:


> JB,
> 
> I see other tiles used in modern looking commercial offices and high rises. But if its adhesion, I guess this makes sense.
> 
> but wait, how does our setter get it to stick onto the ceilings of showers and baths with all the moisture?


You got me


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## JohnFRWhipple (Oct 20, 2009)

drbabs said:


> Recently I have seen two homes with slate tiles for exterior wainscot.
> Frankly, it looked really good.
> why is this not used more often? real and fake stone products are common on exteriors. slate is relatively common on roofs- why not exterior walls?


That is a large mass of stone. I hope they considered thermal expansion when they picked their setting material. With a elevation as tall as that I would have incorporated an expansion strip or added in a second flashing detail mid span so that the longest run was under 10 feet.

A product like Mapei's GraniRapid is an excellent choice for thermal expansion issues.

Check back on this job in a year's time. If it looks like this most likely a cheaper and poorly mixed thinset was used.


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## drbabs (Jul 3, 2011)

JohnFRWhipple said:


> That is a large mass of stone. I hope they considered thermal expansion when they picked their setting material. With a elevation as tall as that I would have incorporated an expansion strip or added in a second flashing detail mid span so that the longest run was under 10 feet.
> 
> A product like Mapei's GraniRapid is an excellent choice for thermal expansion issues.
> 
> Check back on this job in a year's time. If it looks like this most likely a cheaper and poorly mixed thinset was used.


granirapid is the flexible mastic/mortar?
what do you mean by that last comment? You mean the job in your project has cheaper thinset? or it looks like my picture has cheap thinset?

THanks John


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## JohnFRWhipple (Oct 20, 2009)

GraniRapid by Mapei is a S2 Mortar and offers up some degree of flexibility.










Regular thin-set is not and offers up nearly none.

Many stone jobs in Vancouver are installed with Versabond. A basic non modified thin-set with a hint of additive.

I have know idea which thin-set was used on your project but suggest you go back and look in a years time. If the stone was set to tight and no thought was given to expansion those tiles will buckle.

If the wall does not breath and moisture is present then the effloresence will surely develop.

Some of the mason I work with tell me that the problems are resulting in poor quality material and quick or fast speed mixing.


Before jumping into an install like this give the boys at Mapei a call.


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## angus242 (Oct 20, 2007)

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