Live edge mantelpiece

Has anyone experience of wooden mantelpieces. I’d like to make a live edge shelf to go above our fireplace. It will be about 6 feet long and 18 inches wide. Of course, it’s going to get pretty hot when the fire is burning. I’m not concerned about it catching fire but how likely is it to twist and move?

Not all that likely to twist. But that’s almost impossible to predicts due to the size of this slab.

I have to point out that 18” deep is the deepest mantle I’ve ever heard of. They’re generally 6-10”.

18” will be very heavy. It will require a much more significant bracing structure, both to support itself, and the possibility of supporting anything you place on it. And it will be considerably more expensive.

Your average sitting bench is typically 15” deep. My mantle at home is 11” deep and I have concerns about its structural integrity.