Flagstone with plastic mesh in hearth..?

Im currently building a hearth pad for an Ideal Steel. It needs 0.41 R value for the hearth.

I put two layers of 1/2" Durock Next Gen so my R value is 0.78 so I'm already good regarding what the IS needs.

My first question is, I'm putting down flagstone slate tile on the Durock but the tile I purchased has plastic mesh holding 7 pieces together for each segment of the tile. Is it ok to have this plastic mesh imbedded in the mortar in the hearth or do I need to remove each piece and install them individually without the plastic mess?

Also, when securing the Durock to the 3/"4 plywood I used 1 5/8" screws evey 8-10". With the screws under the mortar and slate that go into the plywood that are under the stove, do I have to worry about heat radiating down though the screws and into the plywood???

DougA said:

That sounds exactly the same product as I used on the wall behind the stove. I ended up ripping the plastic mesh off and mortared them one piece at a time. The pieces I has were large and glued to the mesh with hot glue and I instantly found that the stone pieces were not getting a good enough contact with the thinset to adhere properly.
Sorry, can't answer the rest of your questions. Make sure you buy the proper screws for the Durock. It may not matter as much for a flat section but when I did a 16' vertical section, I was told to not use anything but the proper screws.

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Yea I got the screws that were labeled for use for Durock and wonder board.

Like you said the stone sits above the mesh pretty high so I'd have to push the stone in deep to seat it in the mortar