Hearth Pad Advice

[W.B.]

I should have my Micore 300 by the end of the week so I can install the hearth pad over the weekend. The hearth pad will be 1/2" plywood screwed to my existing hardwood floors with 1/2" micore followed by 1/2" durock and porcelain tile. My question is, what is the best way to attach the micore to the underlayment. I would think that any screws that go through the micore would transfer heat into the plywood. Should I just use a heavy duty construction adhesive between the micore and the plywood?

I'm curious what others have done.

 

[begreen]

Construction adhesive is not appropriate for a hearth. There's no need to attach the micore. Just have it captive with the cement board. Get 1 3/4" or 2" cement board screws and screw through the cement board and micore to the plywood. Screw every 8". Don't worry about the heat transfer. It will be negligible.

 

[fire_man]

I agree with begreen. That's what I did - forget the construction adhesive to micore and don't be worried about heat transfer through the screws.

 

[W.B.]

I would've thought that the metal would conduct the heat straight to the plywood and create hot spots. Isn't the whole purpose of the micore to ensure that no heat is transferred to the combustibles?

 

[begreen]

The micro points of the screw tips are not enough to worry about. We are not talking about high heat. Certainly nothing that would accelerate pyrolysis.

 

[W.B.]

Got it. Thanks!

 

[ddahlgren]

Don't screw it to your hardwood floors! it won't move or go anywhere and does not make it a better job. Why scar the floor up for no good reason?

 

[fire_man]

I must be missing something - OP is laying Hearth on existing Hardwood floor - he HAS to screw it down to the hardwood - what else would hold the sandwich in place?

 

[begreen]

Bottom layer is plywood. I would use 3/4" for a better screw bite.