How to install a granite window sill on ETICS?

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I'd be curious to know how your natural stone sills (e.g. granite) were installed if your home has ETICS (=EPS) installed?

One mason says to use staples, another says to just use mounting foam and some mortar. I have another appointment with a third mason, but the confusion for me is already complete.

I found a mason's manual that also lists a bracing option.

Do you have any long term experience with technical reliability?

I would like to avoid the sill being put on top of the EPS and at some point it will sag?



Construction foam and silicone always helps :)

Now let's get serious. I'm no expert, but if someone came to me with construction foam outdoors, where it is constantly exposed to the weather, I would send that person straight home.

Construction foam is not airtight, is not weather resistant, and crumbles after a while.

  • Never, under any circumstances, can something that has been glued together be a suitable support for something heavy. 
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