Installing MICORE 300 Board

There is a certain type of screw used for it, but I can't remember the name or make. I was given some board & the screws from a member here, that is no longer around.
Yes, you can cut it with a knife. I used a saw, with dust mask.
Screwed to substrate and then cement board over the micore, then slate tiles.
I didn't bother taping the seams, but made sure I offset the cement board seams with the micore seams.
The cement board will cover the micore screw heads also.
You will need cement board on top of the micore, as the micore will not support or hold tile.

I doubt there's a screw made to hold micore alone. It has the consistency of pressed newspaper. It needs to be sandwiched. It won't support tile either.

That's correct, what I should have said is there is a specific screw for the cement board, and it will hold both the cement board and micore in place together.

wants to surprise us

I can tell you what I did, that seems to work
First of all, cut the micore with a knife, not a saw, you do not want to breathe in the fibers. The docs at efireplace say you can mortar the tile directly to the micore ( I did not)
I lay down a layer of aluminum flashing to even out heat that gets throught the insulating layer. This was followed by a 1/2 in of micore and 1/2 in of durock next gen. The micore was secured to the underlayment with short durock screws , 8 in on center. The durock was secured to the underlayment with long durock screws, 4 inch on center, that reached all the way to the plywood subfloor. No glue was used between
My tile guy just laid the pieces next to one another, making sure the seams on one layer did not overlap the seams below. The efireplace site says to use furnace cement in the seams of the micore (I did not) . The tile places make a big deal of taping the durock so as to avoid cracks ( this is more a problem with walls). The tile guy tells me he laid down a skin coat on the durock.
Taping a hearth floor, is, in part , a method to avoid hot embers falling through cracks in the tile/fiber/cement board onto the wood below. If you've got a metal sheet on the bottom, this takes care of the 'ember fall through" problem
Finally, to add strength to the mortar layer he used 1/4' hardware cloth (metal screen). The mortar and grout itself was called flexbond an polyblend, which has polymers that make it hold a bit better under bending. If your grout lines are 1/4"in or more, you want to uses sanded grout for strength
You can lay the micore directly on the floor. In my case the sheets were edged on the side by the floor and subfloor. If you lay it on top of an existing floor, I'd use a wood trim to keep the edges from fraying

ref

https://www.hearth.com/talk/threads/mineral-board-or-micore-sources.87737/#post-1404860

Wow, not even going to bother with that. have at it. LMFAO
Have at it...

begreen said:

efireplace is full of it. I would never tile directly to micore and expect a job to stand up. It's much too soft. There is no need to screw the micore first, again it is too soft. Screwing through the cement board with cement board screws every 8" is going to hold the micore perfectly captive.

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Perhaps you consider using a board such as Promat PROMAFOUR which could eliminate the need to use two different materials. You can tile directly to this product and use the cement board screws previously mentioned.

Currently it is sold direct from our factory/warehouse in TN. We are working on establishing distribution currently. R value for 1/2" PROMAFOUR is R = 0.4. Our 1" PROMASIL 1000L has an R value of R = 1.8. PROMASIL 1000L is not supplied thinner than 1". Please find here a link to a video showing more on the product .

Sounds like a competitor to Skamol. Are you guys going to be at the HPB expo?

mellow said:

Sounds like a competitor to Skamol. Are you guys going to be at the HPB expo?

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Yes, we are a competitor to Skamol. To be fair to both parties our systems and approach are a bit different. We will be exhibiting at the HPB Expo in booth # 2835. We would love to have you visit. We will have a demo unit in the booth constructed with the PROMAFOUR system.

Promafour said:

Yes, we are a competitor to Skamol. To be fair to both parties our systems and approach are a bit different. We will be exhibiting at the HPB Expo in booth # 2835. We would love to have you visit. We will have a demo unit in the booth constructed with the PROMAFOUR system.

Click to expand...

Calling @webby3650, got a picture assignment for you

If you are building a hearth that will be covered with tile or other masonry work there is not much difference. However, if someone prefers a clean look to the hearth there is a significant difference. I would definitely agree that the PROMAFOUR system is not for all builds. It is typically used for builds where clean lines or a more "European" look is preferred.