Need some DIY help and advice, Thank you

[Litezoner]

Hello all, so glad you are here, So I am new to the whole fireplace thing, we just bought a house built in 1968, it's around 1000sq ft. We have an old wood burning fireplace with the traditional cinder block, red brick and fire brick box construction. we purchased a fireplace surround made of what I think is real stone, Super heavy, mounted to 3/4 osb, In my pictures I have the fireplace doors installed, I would like to know if it is safe to remove the drywall around the fireplace and attach the piece to the studs behind? it had 4" of flashing around the inside opening of it, I have since flashed over that with another 10", but it is over OSB board which is what concerns me the most, Now the inner part that goes around the fireplace door frame sits around 1" from the frame, I was thinking of applying angle iron all the way around the inside to cover to wood edge which looks to have been coated with something. Very much afraid to just mount this up there with fire caulk and fire spray foam, any and all advice is very much appreciated. Thank you.

 

[begreen]

This doesn't look like real stone, though I am not sure what it is made from. It could be a cement based fake stove product. Some are pretty good looking. It wouldn't hurt to test a discrete area it a bottom "stone". Check by carving it with a knife.

The OSB is flamable.A better way would have been to mortar the fake stove veneer directly onto cement backer board. The metal doesn't do much for protection here. That said, as long as there is 8" of masonry to the sides of the fireplace opening, it is ok to use.

 

[Litezoner]

This doesn't look like real stone, though I am not sure what it is made from. It could be a cement based fake stove product. Some are pretty good looking. It wouldn't hurt to test a discrete area it a bottom "stone". Check by carving it with a knife.

The OSB is flamable.A better way would have been to mortar the fake stove veneer directly onto cement backer board. The metal doesn't do much for protection here. That said, as long as there is 8" of masonry to the sides of the fireplace opening, it is ok to use.

I think that is going to be the problem, I only have about an inch of clearence between the edge of the wood and the fireplace door frame, I think the door frame will get too hot for the OSB and maybe it could ignite, even covered in angle iron.