# Exterior stone treads bonding issue



## Mr Latone (Jan 8, 2011)

I was reading a recent thread on some travertine coping and it appears Laticrete 254 Platinum holds the respect of more than a few.

Here is a stone treaded stair that has bonding issues at the upper most tread. In addition, the outer edges of the slate (mainly the outer edge outside of the porch roof cover) floor have bonding issues.

These are in western NY and experience regular freeze/thaw cycles.

I suspect the mason set the treads in Type S. I don't know about the slate floor.

The bottoms of the treads and slate are clean of the setting material upon removal. The setting material appears to be well bonded to the substrate.

The bed below the treads can be ground down to allow for use of the Laticrete, but what about the slate? The substrate is a concrete slab with a DITRA membrane. Can its surface be lowered by grinding without causing issues to the membrane and its expected performance within the system?


















This small slate has been lifted to show the previously prepared surface. The surface was chipped with a hammer to determine its condition


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## artisanstone (Nov 27, 2007)

I would just reset with the laticrete without messing with the mortar bed. You will end up raising the stones a tiny bit, but it will be all but unnoticeable esp. with the right size notch. Also, that's bluestone, not slate.


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## JBM (Mar 31, 2011)

I agree.


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## CJKarl (Nov 21, 2006)

Saw out the bed, set with choice of stone veneer mortar or laticrete product. Backer rod and Duralink the joint against the terrace. The backer and caulking are needed as a control joint.


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## Mr Latone (Jan 8, 2011)

artisanstone said:


> I would just reset with the laticrete without messing with the mortar bed. You will end up raising the stones a tiny bit, but it will be all but unnoticeable esp. with the right size notch. Also, that's bluestone, not slate.


Thanks for the reply and the correction.

So another question.....

As some of the stones in the field of the floor have lost their bond (a knock with one's knuckles gives a hollow sound), are these stones typically fairly robust or is it likely they would fracture trying to lift them? I am thinking about resistance mainly from grout that is still bonded to the substrate.


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## fjn (Aug 17, 2011)

You could hedge your bet a bit if you took a 4" angle grinder with a diamond blade and "scratched" some groves both directions on the bottom of the stone. Then paint on a bonding agent to the base and the bottom of the stones.:thumbsup:


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## Mr Latone (Jan 8, 2011)

CJKarl said:


> Saw out the bed, set with choice of stone veneer mortar or laticrete product. Backer rod and Duralink the joint against the terrace. The backer and caulking are needed as a control joint.


That certainly sounds fail-safe.

The initial request by the HO was to look at resetting the treads.

The floor stones weren't on their radar. They are, however, very particular and any work that gets done needs to be as permanent a solution as materials allow.

The house is only 6 years old and this type of failure certainly seems to have been preventable?


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## Mr Latone (Jan 8, 2011)

fjn said:


> You could hedge your bet a bit if you took a 4" angle grinder with a diamond blade and "scratched" some groves both directions on the bottom of the stone. Then paint on a bonding agent to the base and the bottom of the stones.:thumbsup:


That little step might prove worthwhile for the treads. I appreciate the input


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## JBM (Mar 31, 2011)

Mr Latone said:


> That certainly sounds fail-safe.
> 
> The initial request by the HO was to look at resetting the treads.
> 
> ...


If there was a direct bond to the concrete with the stone tiles it may have prevented them from popping. The bluestone treads were just not laid in the best material, even mortar can be "ok" if something is brushed on the backside, which it was not. 

Those tiles will always pop and cause issue unless you remove that rubber stuff whatever it is, used for showers right?


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## Mr Latone (Jan 8, 2011)

JBM said:


> If there was a direct bond to the concrete with the stone tiles it may have prevented them from popping. The bluestone treads were just not laid in the best material, even mortar can be "ok" if something is brushed on the backside, which it was not.
> 
> Those tiles will always pop and cause issue unless you remove that rubber stuff whatever it is, used for showers right?


Maybe, but it's multi-pupose. According to schluter's spec sheet

However, with the concrete substrate I don't know exactly what the intended function was in this application.

I posted the question and specifics for the following reasons:


There are a lot of good tradesman on CT
Installation and specification are two distinctly different components to an application
There are times where failure is the result of bad material choice and times where it's poor installation technique
Talented installers using a poor choice of material (maybe not their own) will experience failures
Multiple points of view and experiences will provide a better chance of successful outcome

Thanks for any and all input


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