Hearthpad build question

[70gto]

Hi I'm new to the forum. I got a fisher papa bear that I want to install in my home. It does not have the heat shield best I can tell. I have looked at the nasd guide lines. The legs measure 6 1/2"

My question is in building the hearthpad About the sheet metal. So I plan to remove the carpet in my home. I have wood subfloors. Build a frame out of 2x6 with 3/4 plywood on top of the frame. Then 1/2 durarock or hardy board. A layer of 24 guage sheet metal with another 1/2 durarock on top of that. Finished with tile. Would that be considered proper way to do it or does the sheet metal need to go on top of the layers of durarock or can I just have 2-3 layers of durarock on top of the plywood toped with tile and no sheet metal. Trying to make it look nice and not have the sheet metal visible. But first and foremost it has to be safe. Local building inspector isn't much help. Thanks

 

[MongoMongoson]

You are building a stand out of wood, but your hearth pad starts, in your described install, at the top of that 3/4" plywood sheet.

This is what NFPA 211 says for an unlisted device with 6" or more air gap under it.

You are not installing enough masonry thickness to satisfy NFPA 211.

If you search these forums for hearth pads or floor protection for unlisted installations you should find more info.

I am assuming this Fisher is unlisted, but I might be wrong. Does it have a UL tag?